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.
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.