How Fine Should You Grind Your Coffee? From cafetière to filter to espresso, here’s where to start with your grinder and how to tell from the first sip what to change for the next cup.
Ask a roaster to grind a bag of beans for you and the first question will usually be, ‘How do you make your coffee?’ Easy enough when the bag is for you. Rather harder when it’s for your sister, whose kitchen you know well enough to find the biscuits in the dark, but whose coffee has always appeared in front of you already made.
The answer changes what goes into the bag. For a cafetière, start towards the coarse end of the dial, where you can still see individual flecks of bean. A filter machine generally wants a medium grind; a little finer is a good place to begin for a single cup through a paper cone. A conventional espresso machine calls for fine grounds. How much finer is something you can work out over breakfast, preferably one breakfast at a time. Few of us need to drink six espressos before half past eight to establish that the second one was lovely.
Ten top tips for grinding coffee at home
- Start with the brewer you actually use. If you buy coffee ready-ground, tell the roaster whether you have a cafetière, a drip machine, a pour-over cone or an espresso machine. ‘I like it quite strong’ is useful information, but it doesn’t tell them how to set the grinder.
- Use the guide for your own grinder. One maker’s setting 12 can be a long way from another’s. A friend’s recommendation of ‘a little finer than filter’ travels rather better than their favourite number.
- Weigh one morning’s worth of beans. Ordinary kitchen scales will do for a cafetière or filter brew. A small espresso scale that reads tenths of a gram is handy if you’re working with a basket and a much smaller margin for error.
- Put a pinch of the dry grounds on a white saucer. Tip it towards the window and you can see the difference between distinct little grains and the much finer coffee you’d put in an espresso basket. It’s easier to remember once you’ve seen your own coffee side by side.
- Make a small adjustment. Try one modest step finer or coarser and keep the previous setting somewhere you can find it. A pencil mark on the coffee bag works perfectly well.
- Change one thing per brew. Use the same beans, amount of water and brewing routine for the next cup. If you change the amount of coffee as well, you won’t know which change you preferred.
- Taste it at a temperature you enjoy. Give a very hot cup a minute, then take a proper mouthful. If you drink coffee with milk, try the two brews with the same splash of milk. That’s the drink you’re making.
- Pair what you taste with what you saw. A filter that drained unusually quickly and tastes thin gives you a reason to try finer. A slow, dry-tasting brew suggests a small step coarser. The timing alone tells only half the story.
- If you’re buying a grinder, look at the adjustment. A burr grinder lets you set the gap between two grinding surfaces and return to a setting you liked. If espresso is the plan, check that it allows small changes at the fine end.
- Write down the cup you’d make again. ‘Blue mug, filter, setting 16’ is enough. It’ll be particularly welcome the morning after somebody has borrowed the grinder to make a cafetière for six.
What happens to the water?
Think of a cafetière sitting on the breakfast table. All the water is already in the jug, in contact with the coffee, and there’s time to put the toast on while it brews. Grinding a bean more finely exposes more of it to that water, so flavour can dissolve more readily. The metal mesh lets some of the smallest particles through when you pour, which is why the last mouthful can be a little silty.
Now picture a paper cone balanced on a mug. The water has somewhere to go. As it makes its way through the coffee, the size of the particles helps determine both how readily flavour dissolves and how quickly the water can get out. With espresso, the machine pushes water through a compact bed of fine grounds. That little basket gives the grinder’s smallest adjustments a much bigger say in breakfast.
For the cafetière on the table
Try 30 g of coarsely ground coffee and 500 g of hot water in a jug with room for both. Wet all the grounds, leave them for about four minutes, then lower the plunger gently and pour. If the plunger sticks, don’t lean on it. There’s no prize for getting every last drop through the mesh, and leaving a spoonful in the bottom of the jug does a fair bit for the last person to be served.
Suppose it smells wonderful as you pour, but tastes a little thin and sharp. Tomorrow, weigh out the same 30 g and move the grinder a little finer. Give it the same four minutes. If the cup tastes sweeter and feels fuller, you’ve found a useful change. If the flavour was already lovely and all you wanted was a slightly heftier coffee to stand up to hot milk, leave the grind where it was and try a little more coffee for the same amount of water. How concentrated a cup tastes and which flavours you’ve drawn out of the grounds are two different things you can adjust.
For the filter on a weekday morning
The useful thing about a paper cone is that you can see the water level. Once you’ve made the same mug a few times, you notice when the water hangs about near the top, or disappears almost as fast as you can pour it. For a one-cup V60, the familiar ridged cone with a hole at the base, Hario starts with 15 g of medium-fine coffee and 250 ml of water. Rinse the paper, empty the mug of rinse water, add the grounds and wet them evenly before continuing your pour. With an automatic filter machine, begin nearer medium and use the same batch size each time you compare settings.
Here’s a way to get to know a new bag. With Better Life Elevate RISE, for example, the roaster’s notes are dark chocolate, butter and hazelnut. Make your usual filter and save a little in a cup. Move the grinder one small step finer and make it again. Taste the two at a similar temperature. Can you pick out a nuttier flavour in one? Does one have a pleasant weight to it, while the other leaves your mouth feeling dry? It’s quite possible to prefer the first cup and never once think of a hazelnut.
For the espresso that’s gone through in a hurry
With a conventional single-wall basket, put fine grounds in the basket, spread them evenly and tamp level. Use a dose that fits the basket. If yours is designed for 18 g, put a cup on the scales, zero them and try stopping the shot at 36 g of espresso. That’s what a barista means by ‘one to two’: one gram of ground coffee for every two grams of drink in the cup. Around 25 to 30 seconds is a useful first reference for that recipe. If you have a pressurised or dual-wall basket, follow the machine’s own guide; that basket provides some of the resistance itself.
Say the scales reach 36 g in 17 seconds and the shot tastes sharp and watery. Next time, keep the dose and the 36 g finish, but grind a little finer. If instead the machine can barely coax out a few drops, move a little coarser. And if the shot takes 32 seconds and makes a flat white you’d happily pay for, write down the setting before somebody tidies the bag away.
There is a good reason to resist turning the dial finer every time an espresso disappoints. In a study of espresso brewing, researchers found that beyond a certain point, grinding finer actually reduced the amount they extracted. Their results suggested the water was travelling unevenly through the coffee. At home, that means a slow shot with a sharp taste is a good occasion to check that the grounds are evenly spread, then try easing the grind back a fraction. Sourness on its own is a poor instruction manual.
Sooner or later somebody will ask whether you’ve changed the beans. It’s a satisfying moment when you can turn the bag round and show them it’s the same coffee they had yesterday. And if you’re buying that bag for your sister, send her a text before you get to the counter. ‘Remind me what you make your coffee in?’ ought to do it. You already know where she keeps the biscuits.