数える vs 計る
JLPT N3 vocabulary · what is the difference?
数える is counting things one by one to get a number — people, coins, pages. 計る (はかる) is measuring a quantity with an instrument, above all time and temperature: 時間を計る, 体温を計る. If you can point at each item and say one, two, three, it is 数える.
When to use each
数える
かぞえる
Use 数える when the things are separate and countable and you want to know how many. It always ends in a number of items.
教室の人数を数えました。
きょうしつのにんずうをかぞえました。
I counted the number of people in the classroom.
お金を一枚ずつ数えてください。
おかねをいちまいずつかぞえてください。
Please count the money one note at a time.
計る
はかる
Use 計る when you measure how much of something there is, using a clock, a thermometer or a similar device. It is the standard kanji for time and temperature.
ストップウォッチで時間を計ります。
すとっぷうぉっちでじかんをはかります。
I'll time it with a stopwatch.
熱があるので体温を計りました。
ねつがあるのでたいおんをはかりました。
I had a fever, so I took my temperature.
Sentences where only one works
本が何冊あるか数えます。
ほんがなんさつあるかかぞえます。
I'll count how many books there are.
Separate items, so 数える. A number of books is not something you measure.
五十メートル走るのに何秒かかるか計った。
ごじゅうめーとるはしるのになんびょうかかるかはかった。
I timed how many seconds it takes to run fifty metres.
Seconds are a continuous quantity read off a device, so 計る, even though the answer is a number.
子どもが一から十まで数えられるようになった。
こどもがいちからじゅうまでかぞえられるようになった。
My child can now count from one to ten.
Reciting numbers is always 数える.
毎朝、体温を計っています。
まいあさ、たいおんをはかっています。
I take my temperature every morning.
体温 pairs with はかる, and 計 is the usual kanji for it.
Common mistakes
時間を数えます。
時間を計ります。
Learners map 'count the time' from English. Time is measured, not counted, so 計る is the natural verb; 時間を数える only works in the special sense of counting down the days.
人数を計ります。
人数を数えます。
People are discrete, so they are counted. はかる with 人数 sounds like you are weighing a crowd.
Frequently asked questions
What is the difference between 計る, 測る and 量る?
All three read はかる. 計る is used mainly for time and temperature, 測る for length, distance, area and depth, and 量る for weight and volume. The boundary is not absolute and writers differ, especially between 測る and 量る; when unsure, writing はかる in kana is safe and common.
Which one do I use for height and weight?
Height is normally 身長を測る and weight 体重を量る, following the length-versus-weight split. Many people write both in kana.
Is 数える only for physical objects?
No. You can count anything discrete — days, mistakes, reasons. 数えきれない, 'too many to count', is a common set phrase.