Learn brewing
The science of a better cup.
Seven variables explain almost every cup you'll ever brew. Understand them and every guide, recipe and gadget makes more sense.
01
Grind size
Finer grinds extract faster. Match the grind to your contact time.
Grinding increases the surface area water can reach. The finer the grind, the faster flavor is extracted — and the more resistance water meets as it flows.
Short brews (espresso) need fine grinds; long immersions (French press, cold brew) need coarse ones. Uniformity matters as much as size, which is why burr grinders beat blade grinders.
Sour? Go finer. Bitter? Go coarser.
- Espresso
- Moka
- V60
- AeroPress
- French press
- Cold brew
02
Coffee-to-water ratio
The ratio sets strength. Most filter coffee lives between 1:15 and 1:17.
Ratio is grams of coffee to grams of water. A lower second number means a stronger, more concentrated cup.
Weigh both — scoops vary by up to 30% depending on roast and grind.
Change strength with ratio; change flavor with grind.
- Espresso1:2
- Cold brew conc.1:8
- Moka pot1:9
- AeroPress1:14
- French press1:15
- Pour over1:16.7
03
Water temperature
Hotter water extracts faster. Delicate teas need far cooler water than coffee.
Coffee generally brews best between 90 and 96°C. Light roasts like the top of that range; dark roasts the bottom.
Tea is far more temperature-sensitive: green teas turn bitter above 80°C while black teas need near-boiling water.
Light roast → hotter. Dark roast or green tea → cooler.
- Green tea75–80°
- White tea80–85°
- Oolong88–95°
- Coffee90–96°
- Black tea95–100°
04
Extraction
Too little tastes sour, too much tastes bitter. Aim for the sweet middle.
Extraction is the percentage of the coffee's mass that dissolves into your cup. Acids dissolve first, then sugars, then bitter compounds.
The sweet spot for most coffee is 18–22% extraction — enough to pull sweetness without dragging out harsh bitterness.
Balance lives between 18% and 22%.
05
Brew time
From 30 seconds to 10 days — contact time defines each method.
Brew time is how long water and coffee (or tea) are in contact. It's tightly linked to grind size: shorter brews need finer grinds.
For percolation methods like pour over, total time is a great diagnostic: a slow drawdown usually means your grind is too fine.
Use time as a diagnostic, not a target.
- Espresso30 s
- AeroPress2 min
- Pour over3 min
- French press8 min
- Cold brew16 h
- Kombucha10 days
- log scale
06
Water quality
Your cup is ~98% water. Minerals carry flavor; too many mute it.
Magnesium and calcium help extract flavor, while bicarbonate (alkalinity) buffers acidity. Too much alkalinity makes coffee flat; too little makes it sharp.
A simple carbon filter helps most tap water. For precision, try recipes built from distilled water and mineral concentrates.
Filtered, moderately soft water is the safest start.
- Hardness50–175 ppm
- Alkalinity40–75 ppm
- TDS75–250 ppm
07
Roast levels
Lighter roasts taste of origin; darker roasts taste of the roast.
Light roasts preserve acidity and origin character — florals, fruit and tea-like clarity. Dark roasts trade those for body, bittersweet chocolate and smoke.
Darker beans are more soluble, so they need cooler water and coarser grinds to avoid over-extraction.
Pick your roast for the flavors you want, then adjust heat.
- LightFloral · citrus
- Med-lightFruit · honey
- MediumCaramel · nut
- Med-darkCocoa · spice
- DarkSmoky · bold
Put it into practice
Follow a guide, or let Brewry AI balance every variable for your beans and gear.