Coffee Ratio Calculator
The Coffee Ratio Calculator helps you brew the perfect cup by calculating the ideal coffee-to-water ratio for your brewing method. Enter your desired strength and serving size to get precise measurements in grams and milliliters.
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What is Coffee Ratio?
Coffee ratio is the proportion of coffee grounds to water used in brewing. The Specialty Coffee Association (SCA) recommends a golden ratio of 1:15 to 1:18 (grams of coffee to grams of water). A 1:16 ratio means 1 gram of coffee per 16 grams (ml) of water — producing a balanced, medium-strength cup.
Different brewing methods require different ratios: espresso uses 1:2 (very concentrated), French press 1:15, pour-over 1:16, and cold brew 1:8 (strong concentrate diluted later). Understanding coffee ratios ensures consistency and allows you to fine-tune strength to personal taste.
使用される計算公式・方程式
この計算ツールは5つの主要な公式を使用しています：
1 Coffee Amount ▼
For 500ml of water at 1:16 ratio: Coffee = 500 / 16 = 31.25 grams.
2 Water Amount ▼
Using 20g of coffee at 1:15 ratio: Water = 20 × 15 = 300 ml.
3 Cups to Volume ▼
3 cups at 250ml each = 750ml total water needed.
比率計算ツールの使い方
この比率計算ツールは、以下の3ステップで簡単にご利用いただけます：
数値を入力
入力欄に既知の比率の値を入力します。求めたい未知数の入力欄は空欄のままにしておきます。
モードを選択
比率モード（解く、簡素化、スケーリング）を選択します。各モードで異なる計算式が適用されます。
結果を確認
計算するボタンを押します。結果画面に答えと、視覚的な比率バー、円グラフ、詳細なステップバイステップの解決プロセスが表示されます。
実例問題と段階的な解説
本比率計算ツールを使って、以下の3つの例題をステップバイステップで解決するプロセスです：
入力 1 Pour-over: 2 cups at 1:16 ratio
入力 2 French press: 1 liter at 1:15 ratio
入力 3 Cold brew concentrate: 500ml at 1:8 ratio
よくある質問 (FAQ)
What is the golden ratio for coffee? ▼
The SCA golden ratio is 1:15 to 1:18 (1 gram coffee per 15-18 grams water). For most drip and pour-over methods, 1:16 produces a well-balanced cup. Adjust stronger (1:14) or lighter (1:18) to taste.
How many grams of coffee per cup? ▼
For a standard 250ml (8.5 oz) cup at 1:16 ratio, use about 15-16 grams of coffee. For a stronger cup (1:14), use about 18 grams. For a lighter cup (1:18), use about 14 grams.
What ratio is best for espresso? ▼
Standard espresso uses a 1:2 ratio — 18g of finely ground coffee yields 36g of espresso in 25-30 seconds. Ristretto uses 1:1.5 (shorter, more concentrated), and lungo uses 1:3 (longer, milder).
Why should I weigh coffee instead of using scoops? ▼
Coffee density varies by roast level and grind size. A scoop of light roast weighs more than the same scoop of dark roast. A digital scale (accurate to 0.1g) ensures consistent ratios and reproducible results.
What ratio should I use for cold brew? ▼
Cold brew uses 1:5 to 1:8 ratio for concentrate, then dilute 1:1 or 1:2 with water or milk when serving. Start with 1:8 for a versatile concentrate — you can always add more water but can't strengthen a weak brew.