Coffee Brew Calculator

Coffee Brew Calculator — Ratio, Dose, Yield for Every Method

Pick a brew method, choose how many cups you want, and the calculator works out the exact coffee dose, water volume, and final yield based on the ratio you set. Seven methods are preset with sensible defaults from specialty coffee guidance — V60 1:16, Chemex 1:17, AeroPress 1:14, French press 1:15, espresso 1:2, Moka pot 1:8, cold brew 1:8 — along with grind size, water temperature, and total brew time. Solve for any of the three variables (coffee, water, or yield) and the calculator does the rest, including the bloom + pour schedule for filter methods.

What is a coffee-to-water ratio and why does it matter?

The brew ratio is the weight of dry coffee divided into the weight of water, expressed as 1:N. The Specialty Coffee Association (SCA) Golden Cup standard recommends 1:15 to 1:18 for filter brews, yielding 11-13 g/L of dissolved solids — the so-called "golden cup" zone where extraction balances sweetness, acidity and body. Below 1:14 the cup tastes muddy and overpowering; above 1:18 it tastes thin and sour. The ratio matters because water can only extract a finite amount of soluble material from each gram of grounds, and the dilution sets perceived strength. Our calculator converts a target cup volume into precise gram weights for both coffee and water based on your chosen ratio.

How do brew methods differ in their ideal ratios?

Each method has a sweet spot tied to its contact time and filter style. Pour-over and drip: 1:15 to 1:17. French press: 1:15 to 1:17, since the metal mesh leaves more oils. AeroPress: 1:13 to 1:17 depending on whether you dilute the concentrate. Cold brew concentrate: 1:5 to 1:8, intended to be diluted 1:1 with water or milk before drinking. Espresso: 1:1.5 to 1:2.5 (ristretto to lungo), in the ballpark of 18g in to 36g out for a "normal" double shot. Moka pot: roughly 1:7 to 1:10. Choose method first, then the calculator suggests the right ratio range.

Why measure coffee by weight instead of by scoop or volume?

Coffee beans vary in density by 20-30% depending on origin, roast level, and grind size. A "tablespoon" of light-roasted Ethiopian yirgacheffe weighs noticeably less than a tablespoon of dark French roast. Volumetric measurement therefore introduces a 20%+ swing in extraction strength, which is exactly the range that separates a sour underextracted cup from a balanced one. A digital scale accurate to 0.1 g eliminates this error and lets you reproduce a recipe across days, beans and brewers. Every barista training programme — from SCA to James Hoffmann's tutorials — insists on weighing. Our calculator outputs target weights so you brew the same cup every time.

How does grind size interact with ratio?

Grind size controls extraction speed, not the maximum extractable mass. Finer grinds expose more surface area, so the same ratio at a finer setting yields a stronger, more developed cup; coarser grinds at the same ratio taste weaker and grassy. The interactions are best understood through the SCA brewing control chart, which plots Total Dissolved Solids (TDS, measured by refractometer) against extraction yield. The "ideal" box sits at 1.15-1.35% TDS and 18-22% extraction. If a brew with 1:16 ratio tastes weak, grind finer rather than dosing more coffee. If it tastes harsh, grind coarser, not less coffee — changing only one variable at a time is the rule.

What water temperature should I use?

The SCA recommends 195-205F (90.5-96.1C) at the moment of contact with the grounds. Below 195F you under-extract acids and most flavour compounds; above 205F you start to over-extract bitter alkaloids. Light roasts tolerate the upper end (205F) because they need extra energy to release flavour; dark roasts prefer the lower end (195F) to avoid additional bitterness. For espresso, the group head temperature is usually 200-202F. Boiling water from a kettle hits 212F at sea level; a 30-second rest brings it to roughly 200F, which is why pour-over recipes commonly say "off the boil for 30 seconds." Higher altitudes lower the boiling point by about 1F per 500 ft.

What is the bloom and why include the bloom water in calculations?

The bloom is a short pre-infusion (30-45 seconds) using 2-3 times the dry coffee weight in water — for 20 g of beans, 40-60 g of bloom water. This wets all the grounds, releases CO2 (especially in fresh beans roasted within 14 days), and prepares the bed for even extraction. The bloom water is part of the total brew water, not in addition to it; if your recipe calls for 320 g total and 60 g of bloom, you pour the remaining 260 g in subsequent pulses. Our calculator separates the bloom amount from the main pour so you can target both correctly. Skipping the bloom in fresh coffee causes channeling and uneven extraction.

How do I scale a recipe up or down without losing flavour?

Linear scaling works within a method but fails across methods. Doubling a pour-over from 20 g to 40 g requires not just doubling the water and roughly doubling the brew time, but also adjusting the dripper size and grind slightly coarser (more grounds slow the flow). Going from a single AeroPress to a Chemex carafe with the same total weight changes the entire extraction dynamic — flow rate, contact time, and turbulence all shift. Stick within one method when scaling, and recalibrate grind size between batches. Our calculator gives accurate weights at any scale, but real-world consistency requires keeping the brewer geometry constant.

Should I use filtered water and does mineral content matter?

Yes — water is 98-99% of any brewed coffee by weight, so its composition dominates the cup. The SCA Water Standard recommends 150 mg/L total dissolved solids with a balance of calcium (around 50-175 ppm as CaCO3), magnesium and bicarbonate alkalinity. Distilled or RO water with zero minerals tastes flat and extracts poorly; very hard tap water (above 250 ppm) muffles brightness and rapidly scales espresso machines. Many home brewers use a 1:1 mix of bottled spring water and filtered tap, or specialised products like Third Wave Water. If your tap water tastes good cold, it will likely brew good coffee — the calculator handles ratios, but water quality is your foundation.

How do I hit the SCA Golden Cup extraction window with this calculator?

Set your method and ratio, then enter your extraction yield (EY%) in the strength panel. The calculator computes the estimated brew strength as TDS (total dissolved solids) and shows a verdict badge against the SCA Golden Cup box: extraction yield 18-22% and TDS 1.15-1.35% for filter coffee (8-12% TDS for espresso).

How to use it as a dial-in instrument:

- Measure your actual EY with a refractometer — read TDS, then compute EY = (TDS x beverage mass) / dose. Or simply enter a target EY of 20% to model an ideal brew.
- A green "Golden Cup" badge means both extraction and strength land inside the box.
- "Under-extracted" (EY below 18%) tastes sour and thin — grind finer or brew longer/hotter.
- "Over-extracted" (EY above 22%) tastes bitter and astringent — grind coarser or shorten the brew.
- A "Weak" or "Strong" badge means extraction is fine but the cup is too dilute or too concentrated for the TDS window — adjust the ratio (less water for stronger, more water for weaker) without touching grind.

TDS is computed as mass extracted divided by beverage mass: at a 1:16 ratio with 20% extraction you get roughly 1.25% TDS, squarely in the Golden Cup. Higher EY at the same ratio raises TDS; widening the ratio lowers it. Change one variable at a time and re-check the badge.

Espresso brew ratio 1:2 — is that coffee-to-water-in or yield-out?

For espresso the ratio is a brew ratio measured as dose-in to beverage-out, not coffee to water-in. A 1:2 espresso means 18 g of dry coffee yields 36 g of espresso in the cup — the 36 g is the liquid that lands in your glass, weighed on a scale, not the water your machine pushed through the puck (the boiler uses more, and the puck retains some).

That is why this tool, on the espresso preset, relabels the second result as "Beverage out" rather than "Water": entering an 18 g dose at 1:2 shows 36 g out, which is what a barista targets when dialing in. Filter methods (V60, Chemex, French press, AeroPress, cold brew, Moka) use the opposite convention — there the ratio is coffee to water poured in, and yield is that water minus what the spent grounds absorb.

Named espresso outputs from an 18 g dose: ristretto 1:1-1:1.5 (18-27 g out), normale 1:2 (36 g out), lungo 1:3-1:4 (54-72 g out). Pick the espresso preset, type your dose, and read the beverage-out target directly.

Key Features

• Seven brew methods preset: V60, Chemex, AeroPress, French Press, Espresso, Moka Pot, Cold Brew
• Solve for coffee dose, water amount, or final yield — pick the one you know
• Coffee retention math: subtracts water absorbed by spent grounds
• Step-by-step pour schedule for V60 and Chemex (bloom + three pours with timing)
• Brew schedules for AeroPress, French press, espresso, Moka pot, and cold brew
• Grind size and water temperature recommendation per method
• Metric (grams + milliliters) and imperial (ounces + fluid ounces) units
• Customizable ratio with sensible defaults per method
• Customizable cup size for cup-based recipe scaling
• Specialty Coffee Association-aligned default ratios
• Copy recipe to clipboard with one click
• Works offline after first load
• Pure JavaScript, no external libraries
• Mobile-friendly responsive layout
• 100% client-side — no data sent to a server