By Richard Mayston · Updated October 2026
Under-extracted coffee is sour, and over-extracted coffee is bitter. Measuring the density of your roasted beans tells you which way your coffee is likely to go, and gives you a starting recipe that already suits your roast level.
The recipe sequences and adjustment tools on this site use that density to help you dial in like a pro, up to 5x faster. You don't have to measure your coffee density to use the system, but it is much faster and better if you do.
Roasted coffee density, the weight of 100 ml of beans, tells you how hard or easy a coffee is to extract. Light roasts are dense and hard to extract. Dark roasts are light and brittle. Measure it, enter it on this site, and every extraction parameter is set for your actual roast level instead of a fixed recipe built for someone else's coffee.
Each section links to the full explanation further down the page.
Reason 1
Under-extracted coffee is sour, and over-extracted coffee is bitter. It really is that simple, and it is why the recipe sequences and adjustment tools on this site exist: to help you dial in your extraction quickly and avoid sour or overly bitter coffee.
It is easy to over-extract a dark roast, and just as easy to under-extract a light roast. By measuring the density you get a starting recipe that is far more likely to suit the extraction your roast level needs, so you aren't starting from a recipe written for a different coffee.
Under-extracted. Extract more by moving to a higher-numbered recipe.
Over-extracted. Extract less by moving to a lower-numbered recipe.
That is the second benefit of measuring. You also get much more effective adjustments. Instead of using up most of your bag of beans blindly trying to work out the right formula, you taste, move one step up or down the series, and repeat. Not sure where to start? Enter your density in the coffee density calculator to get your starting recipe.
Reason 2
Only about 30% of a coffee bean's mass is solubles. The other 70% is the insoluble fibre and carbohydrate that gives the bean its structure.
These are the sweet, pleasant flavours. This is what you want in the cup.
These taste awful. They are larger molecules and take longer to dissolve.
Luckily, because the bad solubles dissolve more slowly, we can vary the extraction parameters to release the good ones while leaving the bad ones locked inside the cells. That is the sweet spot between sour under-extraction and bitter over-extraction. For more detail, read An Intuitive Guide To Coffee Solubles, Extraction, and TDS on Hand Ground.
The SCA's guideline for extraction is 18 to 22%, meaning that share of the dry coffee's mass ends up dissolved in your cup. Maximising extraction yield is not the goal, because you will end up with bitter coffee. The real problem is how easy or difficult it is to extract just the right amount, and that changes completely with roast level.
Reason 3
Coffee beans have some of the strongest cell walls in the plant kingdom. When coffee is roasted, the heat and the conversion of water into gas create high pressure inside the bean. That changes the cell walls from rigid to rubbery, because of the polysaccharides (bonded sugar molecules) they contain.
The internal matter pushes out towards the cell walls, leaving a gas-filled void in the centre, so beans expand in volume as they lose mass. Much of that gas is carbon dioxide, released after the roast. Roasting also increases porosity, making the beans less dense and more soluble. See the physical changes coffee beans experience during roasting at Perfect Daily Grind.
Most of the water remains inside the bean, so it is heavy for its size and the cell walls stay very hard. If you have ever hand-ground a light roast you know it is like grinding rocks. It is difficult to extract enough without sourness, and every tool and parameter needs to be dialled up.
Much of the water has boiled off, and the steam has damaged the cell walls, leaving the bean light and brittle. You can crush one between your fingertips. It is easy to over-extract into bitterness, so every tool and parameter needs to be dialled down.
There are not just three roast levels of light, medium and dark. Green beans are roasted between 190°C and 240°C, a 50-degree range, with different durations and roast curves. How quickly the beans are brought up to temperature, and how long they are held at each point, gives you a whole roast spectrum. It is quick, cheap and easy to find where your coffee sits on it by measuring the density. See the coffee roast levels chart for roast names, density and the recipe for each roast.
Reason 4
Density is weight divided by volume. For coffee, you weigh 100 ml of your roasted whole beans in a good quality (±0.5 ml) graduated cylinder on good scales (±0.1 g). The result, in grams per millilitre, is a direct measure of how roasted your coffee is.
The Acaia Pyxis and Acaia Lunar are excellent because they are accurate to 0.01 g with a fast refresh rate, but a good range suits every budget, such as the TIMEMORE Black Mirror Basic Plus 2021. For the process, read how to measure coffee beans or watch Measuring Coffee Density.
100 ml of beans weighs as little as 33 g.
100 ml of beans weighs as much as 45 g.
That is the real-world range: from 33 g to 45 g per 100 ml in 0.1 g steps, which gives 120 steps and 121 different roast levels. Where your coffee falls on that spectrum dramatically changes the level of extraction needed to hit the sweet spot, and it is much more precise than a roast name.
Frequency distribution of measured roasted coffee density. Most coffees sit in the middle of the range, with the espresso and V60 recipe parameters shown below the chart.
Density correlates directly with roast level, which is why a single measurement can set up so many parameters at once. The rest of this page shows how.
Reason 5
A traditional fixed espresso recipe looks like 20 g in, 40 g out, a 1:2 ratio, 93°C and 25 seconds. The grind size is the only parameter you change. Fixed recipes assume everything is roasted to one of two levels, espresso or filter. Apart from being demonstrably not true, that also limits what you can use the espresso method for.
A density-based recipe is a variable recipe. Each extraction parameter is set relative to where your coffee falls on the 121-step density range. You measure the density, enter it on this site, and the site does the calculations and gives you appropriate espresso and filter recipes. I call the method Density Assisted Extraction (DAE), a catchy acronym like WDT and RDT, and the recipes themselves are the Coffee Recipe Series (CRS).
You need to get all ten wheels in the right place to unlock a great extraction. With a fixed recipe, you have no say over nine of them.
Nine of the ten wheels are most likely in the wrong place, and you are turning one wheel, the grind, in the hope of unlocking it. You make large grind changes, it takes a lot of trial and error to dial in a new coffee, and many people never experience well-extracted coffee and get used to bitter coffee.
Nine of the ten wheels start in the correct place and you make a minor grind adjustment to the last one. That means much smaller grind changes, much less dialling in, and the ability to cope with a wider range of roast levels. You would be amazed how often you nail a new coffee the first time.
Until now there has not been a good tool to measure roast level, so roast level has been ignored as something that needs to be factored in. Now there is a cheap tool and a good method. If you want to handle an endless variety of coffees reliably, a measuring cylinder is a low-cost thing to try with a great return on investment.
If you only ever use one favourite blend that never changes, you may not need this so much. Even then, today's mid-roast is much lighter than when the standard fixed recipe was invented, and you could benefit from some tweaks.
Background
The 1:2 ratio evolved back in the 1960s, when Robusta proportions in blends rose to as much as 75% in Italy and France because of widespread coffee rust dieback of Arabica. Espresso roasts went very dark to mask Robusta's low-quality flavour and inherent bitterness, and became known as French Dark and Italian Roast. A 1:2 ratio with a 25-second shot was an average recipe that would do.
Recently there has been much more use of Arabica and a desire to roast lighter so you can enjoy the terroir differences, and baristas have moved towards 1:2.5 to 1:3. But the sweet spot remains elusive, because you are unlikely to hit it without tailoring every parameter to the actual roast level out of 121 levels of roasted bean density.
You hear of the God Shot, the once-in-a-lifetime perfect espresso. When people do experience a well-extracted coffee, the most common response is surprise. I once gave a black coffee to someone who habitually takes milk and sugar, and they were stunned they could enjoy a black coffee.
Espresso tools 1 to 3
Espresso is a wonderful method of making coffee because it gives you a great set of tools for managing extraction. You need to actually vary each of them with roast level, not fix them. The core parameters are ratio, dose, yield, temperature, pressure and time. The supplementary parameters are basket size, cup size, grind size and bypass water. Every one changes depending on where your coffee falls on the 121-step density spectrum, and then you still correct for taste.
Water is a powerful solvent, and the ratio of water to coffee is possibly the most powerful tool you have and typically the most underused. The espresso ratio ranges from 1:1 for a very dark roast to 1:4 for a very light roast.
Dark roast: if you use a fixed 1:2 or 1:3 ratio you put through far too much water and over-extract. No amount of grind adjustment can compensate, and you make a bitter coffee, which is why most people put a ton of milk and sugar in dark roasts.
Light roast: a fixed 1:2 or 1:3 ratio puts through far too little water and under-extracts, so the coffee is sour. This is why most people don't even try light roasts on espresso and stick to filter. They are missing out, because you can have wonderful taste experiences with light roasts when they are extracted properly.
Dose means the weight of dry ground coffee. When the ratio changes across the roast spectrum it is really useful to change the dose too.
With a very light roast at a 1:4 ratio, a 14 g dose gives a just-manageable 56 g yield. A 20 g dose would need a massive 80 g, which exceeds the brew chamber of devices such as the Flair 58. It is much easier to achieve high ratios when you reduce the dose. With a very dark roast at 1:1, increasing the dose to 25 g keeps the yield up at 25 g.
Yield means the weight of coffee made, and yield = dose × ratio. For example, a 20 g dose at a ratio of 2.5 should give a 50 g yield. Put your scales under the cup and stop the shot when it reaches the target yield. The important thing is to keep the ratio constant: if you can only fit 18 g in your basket, your yield is 18 × 2.5 = 45 g.
Espresso tools 4 to 6
Higher temperatures extract soluble compounds much more easily than lower ones. For espresso, where contact time is very short, a light roast wants 95°C, a medium roast 90°C and a dark roast 85°C. Your coffee is likely to sit somewhere between those extremes.
Interestingly, mid-roasts, which fall around 0.390 g/ml, need 89 to 90°C, somewhat below the SCA-recommended 93°C. People are waking up to the fact that mid-roasts taste better at a lower temperature than fixed recipes use, and you can see it in many winning AeroPress competition recipes.
Flair 58: it sensibly has three temperature settings: 1 light is 85°C, 2 lights is 90°C and 3 lights is 95°C. For the most common roast levels, use setting 2 at 90°C.
Pressure was introduced to cut the time it takes to make a coffee: nine bar can produce a shot in 25 seconds, compared with around four minutes for filter. With a dense, lightly roasted bean, holding 9 bar helps cope with a finer grind and extract the most sugars. With a very dark, brittle bean that is easily over-extracted, a gentle 6 bar caters for a coarser grind and helps avoid over-extraction. Read more about nine-bar espresso pressure.
Increasing the shot time increases extraction, so for a very light roast, going up to 40 seconds helps. With very dark roasts, cutting the shot time to as little as 20 seconds helps avoid over-extraction. These times are for a standard 58 mm basket. Smaller-diameter baskets have a deeper bed and need more time.
Espresso tools 7 to 9
Using the correct ratio for the roast level changes the dose, and so it changes the basket. A dark roast needs a 1:1 ratio, where a 25 g dose gives a 25 g yield. A very light roast needs 1:4, where a 14 g dose gives a 56 g yield. VST Precision Filter Baskets are optimised for specific dose capacities of 7, 15, 18, 20, 22 and 25 g, and the hole size, number and placement vary across the sizes to deliver consistent extraction.
VST measures every hole in every basket, and VST baskets produce significantly more consistent results than OEM baskets. See Clive Coffee on whether portafilter baskets matter, how filter baskets affect espresso taste at Home-Barista, and my guide to how to choose an espresso basket.
A very light roast needs a low dose, a high water ratio and some bypass water, so a small 5 oz (150 ml) cup will taste better than a large cup that washes it out. A very dark roast is ashy and burnt-tasting, and a large volume of milk helps make it more palatable, so a larger 8 oz (236 ml) cup suits it. Your coffee is likely to sit somewhere between those extremes, and changing your cup size to suit the roast level is recommended.
Cups from Acme: flat white (150 ml), tulip (170 ml), cappuccino (190 ml) and latte (280 ml).
A very lightly roasted coffee needs a low dose and a high water ratio. If you then add a lot of milk, as most people do with flat whites, lattes and cappuccinos, the delicate fruit, acidity and aroma of a light roast are easily overwhelmed. Replacing some of the milk with hot water that has bypassed the extraction bed, which avoids over-extraction bitterness, brings out the full range of flavours. Bypass is common in Americanos and long blacks, but with the trend towards lighter roasts it should be used with milk drinks too. A very dark roast needs no bypass, because a large volume of milk makes it more palatable.
Espresso tools 10 and 11
There are so many combinations of espresso machines, grinders, burr sets and baskets that giving one universal grind setting is almost impossible. Density can still help. If you set the dose, ratio, yield and temperature correctly, and know the shot time you are aiming for, you will need smaller grind changes, so getting your grind about right is much easier. If you record your own ideal grind settings against density, you will cut your dialling-in time significantly.
The grind sizes on this site are in microns, for my Kafatek Monolith MAX with 58 mm VST baskets, so your mileage may vary. I recommend getting a Kruve Brewler and measuring the microns your own grinder produces at each setting, which also shows you how consistent it is. A few reference points:
Microns
Kafatek Monolith
Option-O
Kinu M47
200
2
0.8
1.2.8
300
3
1.2
1.5.0
400
4
1.7
1.7.2
500
5
2.2
1.9.4
600
6
2.7
2.1.7
800
8
3.6
2.6.1
1000
10
4.6
3.0.6
For more settings, see grind settings by density.
You should always taste your coffee, even as you make it. Catch the last few drops in a teaspoon: if they are still sour you need to grind finer, and if they are sweet you are there. For more on tasting extraction, read Coffee Extraction and How to Taste It at Barista Hustle.
On every recipe page
Beyond the extraction parameters, each recipe page shows a few extra pieces of information.
This shows where your coffee falls on the density range, where 0% is the lightest roast level you are likely to encounter and 100% is the darkest.
This is information for coffee roasters. For the basics, see Roasting coffee basics at CoffeeNavigated.
You've probably heard a few roast names. Some refer to the bean's appearance (Cinnamon), the region it's from (Viennese) or when it should be drunk (After Dinner). There is little standardisation: some terms are used interchangeably, others describe a range of roast levels, and the names don't directly reference flavour or aroma. Light City, Half City, Cinnamon, New England, American, City, Full City, Vienna, French and Italian are all in use.
You are much better off measuring the density to find out which of the 121 roast levels you have. Read what coffee roast names really mean at Perfect Daily Grind, or see the coffee roast levels chart.
Milk and coffee are a marriage made in heaven. Steamed to 60°C, milk reaches its optimum sweetness. Aerate it just enough to produce a thick paint texture.
Filter coffee
The same principles apply to filter coffee. Every filter parameter is varied relative to roast level, as measured by density, instead of being fixed.
Filter ratios run from 1:13 for a very dark roast that needs little water to extract, up to 1:20 for a very light roast that needs lots of water.
With a much longer contact time, and more heat lost over the brew, filter coffee needs higher temperatures than espresso. A light roast wants 95°C, a medium roast 93°C and a dark roast 90°C.
Lighter roasts need more contact time to extract, and darker roasts need less.
Filter water is usually fixed in volume to match the cup size, so the dose is varied in order to change the ratio. I use a 480 ml Hario drip pot with a cloth filter to let the coffee oils through. A single cup doesn't give enough bed depth, so it works better as a two-cup brew.
Storage and resting
A resting calculator used to be a feature of recipeseries.coffee. After reading the SCA Coffee Freshness handbook and running a series of tests myself, I replaced it with advice on how to maximise coffee freshness.
Roasting traps carbon dioxide inside the bean, and it is released over time, which is why good coffee bags have a one-way valve. The theory behind resting is that coffee used straight after roasting can taste sour, because so much CO2 in contact with the hot water stops it penetrating and extracting properly. How fast beans degas depends on roast level. A very dark, porous roast degasses quickly and may reach its theoretical peak in as little as four days, while a hard, dense light roast releases gas slowly and might not get there for a month or more.
The volatile organic compounds that give coffee its aroma and flavour leave with the CO2 through the valve, and they are lost fast. If you want peak flavour and aroma, freeze your beans as soon after roasting as possible. If excess CO2 is causing you problems, use pre-infusion rather than resting.
I single-dose my coffee and freeze it in reusable 70 ml pots for espresso, or 50 ml centrifuge tubes for filter-sized doses. Read the full guide, how to store coffee beans: 9 tips, or why and how you should freeze coffee beans at the Barista Institute.
Tools compared
A coffee refractometer costs about $730 USD, and all it tells you is the total dissolved solids (TDS) percentage. Maximising TDS does not make a better cup of coffee. A 100 ml graduated cylinder is cheap, about $15 on Amazon. Measure the density, use this site, and you get a brew guide with the temperature, dose, yield, ratio, pressure and contact time, and you can even work out a starting grind size. It helps you optimise for sweetness.
Tells you one number, the TDS percentage of a coffee you have already brewed.
Tells you the roast level of the beans before you brew, so every parameter can be set for them.
Evidence
recipeseries.coffee is blindingly simple. Users have submitted about 6,400 independent measurement sessions, and the data have been cleansed of default values, rounded readings and repeat entries. Simple statistical analysis gives the median, the spread and how much of the coffee each part of the range covers. The real-world roasted coffee density range used on this site, 0.330 to 0.450 g/ml, holds about 90% of it (how the range was determined).
The extraction recipes are generated from a lot of research, testing and ongoing revision. They use computer modelling that predicts over 5,000 data points, and the model has been successful enough that I personally would not now make coffee without it.
In an ideal world, coffee roasters, who often do 60 kg batch roasts, would measure the density for you, and you would find the roast date, density and a QR code on every bag you buy. But using roasted coffee density is brand new and it might take a while to catch on. You can start today with a graduated 100 ml cylinder. If you are a roaster, read the value proposition for coffee roasters.
The benefits of measuring density to assist with coffee extraction are a liberating revelation. Exploring the wonderfully diverse world of specialty single-origin coffee becomes a safe and enjoyable prospect when you no longer fear handling a challenging light roast.
FAQ
Roasted coffee density is the weight of a fixed volume of roasted whole beans, usually 100 ml in a graduated cylinder, expressed in grams per millilitre (g/ml). Real-world coffee runs from about 0.330 g/ml for a very dark roast to 0.450 g/ml for a very light roast.
Density tracks roast level. A dense, light-roasted bean has hard cell walls and is difficult to extract, so it needs more extraction. A less dense, dark-roasted bean is brittle and easy to over-extract, so it needs less. Knowing the density lets you set the ratio, dose, temperature and other parameters for your actual roast level instead of using a fixed recipe.
Fill a 100 ml graduated cylinder (accurate to ±0.5 ml) with whole beans, weigh them on scales accurate to 0.1 g, and divide the weight in grams by 100 to get g/ml. For example, 39 g in 100 ml is 0.390 g/ml. Read how to measure coffee beans for the full method.
No. If you don't have a measuring cylinder, start at recipe 51 (380 g/L), which sits at the centre of recent measurements, then taste. If the coffee is sour, move to a higher-numbered recipe to extract more. If it is bitter, move to a lower-numbered recipe to extract less. Measuring density just gets you a much closer starting recipe and more effective adjustments.
Very dark roasts are around 0.330 g/ml and very light roasts around 0.450 g/ml, with mid-roasts around 0.390 g/ml. Roast names are not standardised, which is why the measurement is more reliable than the name on the bag. See the coffee roast levels chart, and how the 330–450 g/L range was determined from the measurements.
Yes, the same principle applies. Filter ratios run from about 1:13 for a very dark roast to 1:20 for a very light roast, temperatures from 90°C for dark roasts to 95°C for light roasts, and lighter roasts need more contact time.
They do different jobs. A refractometer measures the TDS of coffee you have already brewed, and maximising TDS does not make a better cup. Density measures the beans before you brew and sets up the whole recipe. A graduated cylinder costs a fraction of the price.
I replaced the resting calculator with storage advice. Most of the aroma is lost within about ten days, so I freeze single doses as soon after roasting as possible, and use pre-infusion if excess CO2 is a problem. Read how to store coffee beans.
It depends on density. The ratio runs from roughly 1:1 for a very dark roast to 1:4 for a very light roast, while the dose falls from 25 g to 14 g across the same range. Enter your density in the coffee density calculator to get exact figures.
Keep reading
Roast names, density and the recipe for every roast level.
The full method for measuring roasted coffee density with a cylinder and scales.
Starting grind sizes across the density range.
Why to freeze single doses and grind them frozen.
Six tips for buying beans worth brewing.
15 tips for a grinder that maximises flavour.
Basket size and dose for your roast level.
The computer modelling behind the recipe series.
The articles I referred to while writing this page.
An Intuitive Guide To Coffee Solubles, Extraction, and TDS (Hand Ground)
Physical changes coffee beans experience during roasting (Perfect Daily Grind)
What do coffee roast names really mean? (Perfect Daily Grind)
Coffee Extraction and How to Taste It (Barista Hustle)
Portafilter baskets: do they matter? (Clive Coffee)
How filter baskets affect espresso taste and barista technique (Home-Barista)
Freezing Coffee Beans: Why and How You Should Do It (Barista Institute)
TDS or Total BS (Seattle Coffee Works)
Roasting coffee basics (CoffeeNavigated)
