From grams of coffee to exact water — dial in 1:15 strong, 1:16 balanced, or 1:17 mild.
Two tablespoons per cup. Four scoops per pot. A “coffee scoop.” Every kitchen has a folk recipe for coffee strength, and every one of them is vague — because a scoop of dark roast weighs less than a scoop of light, and “a cup” might be 6 ounces or 8. Our free Coffee Ratio Calculator replaces folklore with weight: enter grams of coffee, pick a brew ratio, and get exact water in milliliters and grams, plus the cup count.
Coffee brewing is extraction: hot water dissolves flavors from ground coffee, and the two variables that matter most are ratio (coffee mass to water mass) and grind/contact time. Ratio sets strength — how concentrated the cup is — while grind and time set extraction — which flavors come out. Too little water per gram and the cup is harsh and muddy (over-extracted); too much and it’s thin and sour (under-extracted). The specialty industry’s consensus golden ratio is 1:16 to 1:17 (coffee:water by weight), the range where sweetness, acidity, and body balance for most palates.
Weigh your coffee, choose 1:15 (strong), 1:16 (balanced), or 1:17 (mild) — the widget does the water math.
A brew ratio is coffee mass : water mass. 1:16 means 1 gram of coffee per 16 grams of water — so 30 g of coffee needs 480 g of water, and since 1 ml of water weighs ~1 g, that’s 480 ml. Weight is used because volume lies: a tablespoon of fluffy light-roast grounds can weigh 7 g while a tablespoon of dense dark-roast weighs 12 g. Same spoon, 70% different dose. The scale doesn’t care about roast level.
Extraction is the percentage of the coffee’s mass that dissolves — the specialty target is 18–22%. Below that: sour, salty, thin (under-extracted). Above: bitter, dry, hollow (over-extracted). Ratio controls strength (total dissolved solids, TDS); grind size and brew time control extraction. Confusing the two is the classic home-brewer error: a weak cup gets “fixed” with a finer grind when it needed a stronger ratio, producing a cup that is both weak and bitter.
The three ratios on this page: 1:15 (strong) — concentrated, syrupy, the choice for milk drinks where dairy dilutes; 1:16 (balanced) — the SCAE golden-ratio neighborhood, the starting point for dialing in any new coffee; 1:17 (mild) — delicate, tea-like, lovely for floral light roasts but flirting with under-extraction sourness if the grind is coarse. Espresso lives outside this system (1:2, pressure-extracted) — this calculator is for drip, pour-over, French press, and cold brew.
Key terms:
Water’s density makes grams and milliliters interchangeable — the one unit conversion you never have to think about.
You want one big mug, ~350 ml, at balanced strength.
The calculator runs forward (coffee → water); invert it when the mug size is fixed.
Four guests, ~250 ml each = 1000 ml, and press pots are forgiving — go 1:15 for richness.
Press math is the same ratio math; only grind and time change with the method.
A bag of Ethiopian light roast arrives. Protocol: start at 1:16 (30 g → 480 ml), medium grind, 3:00 pour-over. Taste: bright but thin — strength issue, not extraction. Move to 1:15 (30 g → 450 ml): now syrupy but a bitter edge — extraction slightly high at the stronger ratio. Coarsen the grind one click, keep 1:15: balanced, sweet, floral. Three brews, two variables changed one at a time — ratio first, grind second is the dialing-in order because ratio changes are predictable (linear) while grind changes interact with time. Log the winner: “Ethiopia, 30 g, 450 ml, 1:15, grind 18 clicks.” That log entry is a recipe; the calculator regenerates it for any batch size.
Second scenario: the office urn. 60 cups needed — but “cups” on urn markings are 5-oz cups, not 8-oz. 60 × 5 oz = 300 oz = 8.85 L. At 1:16: 8850 ÷ 16 = 553 g coffee — just over a pound. The two classic urn errors are using 8-oz math on 5-oz markings (weak urn) and eyeballing half a bag (chaos). Weigh it.
Third: cold brew concentrate. Cold brew runs 1:8 to 1:10 as a concentrate, diluted 1:1 after. For 1 L of concentrate at 1:8: 1000 ÷ 8 = 125 g coarse coffee, steep 12–16 hr. Diluted, the drinking cup lands near 1:16 — the same golden ratio, reached by a different road. The calculator’s 1:15–1:17 range covers the drinking strength; concentrates are a separate (stronger) regime.
Fourth: the moka pot translation. A 6-cup moka pot uses ~30 g coffee to ~300 ml water — effectively 1:10, stronger than drip because the method extracts under steam pressure with a fine grind. If it tastes harsh, don’t change the ratio (the pot’s geometry fixes it) — use slightly cooler water off-boil and a touch coarser grind. Ratio is fixed by the hardware; extraction is the free variable.
Specialty cafes: every recipe on the bar is a ratio — 1:16 drip, 1:2 espresso — so any barista reproduces any drink. Ratios are the industry’s language.
SCAE brewing standards: the Golden Cup standard (55 g/L ≈ 1:18 at the mild edge) came from 1950s brewing research — the ancestor of every ratio chart.
Instant coffee: sachets are pre-ratioed doses (typically ~2 g per 150 ml ≈ 1:75, very mild) — which is why instant tastes thin to drip drinkers.
Cupping: professional tasting uses 8.25 g per 150 ml (1:18.2) across all coffees — fixed ratio isolates the coffee’s own character.
Industrial extraction: instant-coffee factories optimize the same extraction percentage (18–22%) at ton scale — your pour-over and their percolation columns share the chemistry.
Tea: 2–3 g per 250 ml (≈ 1:100) — tea’s ratios are an order of magnitude milder, which is why coffee math surprises tea drinkers.
One pattern worth internalizing: ratio sets strength, grind/time set extraction — diagnose which is wrong before changing anything. Sour + weak: strengthen ratio. Bitter + strong: coarsen grind. Weak + flat: strengthen ratio. This two-axis diagnosis fixes 90% of bad cups.
A short history: ratio brewing is young. Until the 1950s, coffee was made by color (“strong enough”) — the Coffee Brewing Institute’s research under Dr. Ernest Lockhart produced the first brewing control charts and the 55 g/L golden-cup standard. The third-wave refinement to 1:15–1:17 and the 18–22% extraction target came from the Specialty Coffee Association’s later work. Your kitchen scale is the heir of that research.
Edge cases and pro tips: very fresh coffee (1–3 days off roast) needs a slightly coarser grind or milder ratio — CO2 off-gassing fights extraction. Dark roasts extract faster: start 1:16 but grind coarser than you would for light. High altitude: water boils below 205°F — just off-boil is automatically correct. And blooming (wetting grounds 30–45 s before the main pour) matters most for fresh coffee; for month-old beans it’s ritual, not chemistry.
When ratio math is the wrong tool: espresso is dialed by yield (1:2 in 25–30 s), not by this calculator’s immersion ratios — different physics. Turkish coffee is eyeballed by tradition (and delicious for it). And if the coffee itself is stale, no ratio rescues it — fresh beans beat perfect math with old beans.
Coffee Ratio Calculator: water(ml or g) = coffee(g) x ratio number. Ratios: 1:15 strong, 1:16 balanced golden ratio, 1:17 mild. 30 g at 1:16 = 480 ml = ~2 US cups. Weigh coffee in grams; scoops vary 40%+. Ratio controls strength, grind/time control extraction (target 18-22%). Brew 195-205F. For drip/pour-over/press; espresso uses 1:2. Source: Sigma Calculator, Coffee Ratio Calculator, https://sigmacalculator.net/cooking-calculators/coffee-ratio-calculator/
Cite this page as: Coffee Ratio Calculator, Sigma Calculator, https://sigmacalculator.net/cooking-calculators/coffee-ratio-calculator/
Last updated: October 12, 2026