Translation guide
In Japanese, expressing 'ratio' depends on whether you are comparing two numbers, describing a proportion, or talking about a rate. Common words include 割合 (わりあい) for general proportions, 比率 (ひりつ) for formal ratios, and 倍 (ばい) for multiples.
Expressing the relationship between a part and a whole, or a general proportion.
The most common and versatile word for 'ratio' or 'proportion'. Used in everyday conversation.
男性と女性の割合はどのくらいですか。
What is the ratio of men to women?
このクラスの留学生の割合は高い。
The proportion of international students in this class is high.
A more formal or technical term for 'ratio', often used in business, science, or statistics.
利益率の比率を計算してください。
Please calculate the profit margin ratio.
A suffix meaning 'rate' or 'ratio', often used in compound words like 成功率 (success rate) or 失業率 (unemployment rate).
失業率が上がっている。
The unemployment rate is rising.
Expressing a specific ratio between two numbers, like 2:1 or 3:5.
Used to express a ratio of A to B. A and B are numbers.
その溶液は水とアルコールを1対3の割合で混ぜます。
The solution is mixed in a ratio of 1 to 3 of water and alcohol.
A more formal way to say 'the ratio of A to B'.
生徒の教師に対する割合は20対1です。
The ratio of students to teachers is 20 to 1.
Expressing how many times one quantity is compared to another.
Means 'times' or 'fold'. Used to say something is X times as much.
この部屋はあの部屋の2倍の広さです。
This room is twice as large as that room.
価格が3倍になった。
The price tripled.
Expressing a ratio per unit, like per person or per hour.
Attached to a unit to mean 'per'. Very common.
1人あたりの費用は5000円です。
The cost per person is 5000 yen.
時速100キロは、1時間あたり100キロ進む速さです。
A speed of 100 km/h means traveling 100 km per hour.
割合 is the most general and colloquial. 比率 is formal and often used for precise numerical ratios. 率 is a suffix for rates (e.g., 確率 probability, 利率 interest rate).
割合：この町の高齢者の割合は増えている。
The proportion of elderly people in this town is increasing.
比率：男女の比率はほぼ1対1です。
The male-to-female ratio is almost 1 to 1.
率：合格率は80%だった。
The pass rate was 80%.
English 'ratio' is often used where Japanese would use 割合 or 倍. For example, 'the ratio of sugar to flour' is 砂糖と小麦粉の割合, not 比率 in casual cooking contexts. Also, 'price-performance ratio' is コストパフォーマンス or コスパ, not a direct translation.