未満 vs 以下: “Under” vs “Up To” — Does the Number Count?

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未満 (miman)以下 (ika)
MeaningLess than X / under XX or less / up to and including X
Includes the number?No — strictly belowYes — X is included
English equivalent“Under X” / “Less than X”“X or less” / “X and under”
Example20歳未満 = under 20 (19 and below)20歳以下 = 20 and under (20 included)
Yuka

What’s the difference between 未満 and 以下? They both seem to mean “under.”

Rei

The key is whether the number itself is included! 未満 means strictly LESS THAN — the stated number is NOT included. 以下 means UP TO AND INCLUDING — the stated number IS included.

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What Does 未満 (miman) Mean?

未満 means less than or under — strictly below a number, not including it. 未 means “not yet” and 満 means “full/complete.” So 未満 literally means “not yet reaching.” This is the word used in laws and regulations where precise exclusion of the boundary matters.

  • 20歳未満の飲酒は禁止です。 — Drinking alcohol is prohibited for those under 20 (under 20 = up to 19).
  • 定員20名未満の場合は開催しません。 — We will not hold the event if attendance is under 20.
  • 100万円未満の収入。 — Income of less than 1 million yen.
  • 18歳未満お断り。 — No entry for those under 18 (18-year-olds must not enter).

What Does 以下 (ika) Mean?

以下 means or less or up to and including. It is inclusive — the stated number is part of the range. 以 means “from,” and 下 means “below.” It is the counterpart to 以上 (or more).

  • 15歳以下は無料です。 — Children aged 15 and under (including 15) are free.
  • 5,000円以下の商品。 — Products priced at 5,000 yen or less (5,000 included).
  • 気温が10度以下になった。 — The temperature fell to 10 degrees or below.
  • 以下の条件を満たす方。 — Those who meet the following conditions.

The Critical Distinction

Age / Number未満 (miman)以下 (ika)
20歳___19 and below (20 NOT included)20 and below (20 included)
18歳___17 and below18 and below
100点___99 and below100 and below
0度___Negative temperatures only0 degrees and below
Yuka

Which one is used for Japan’s legal drinking age?

Rei

20歳未満の飲酒は禁止 — 未満 is used because the law means “strictly under 20.” 20-year-olds CAN drink. If it said 以下, then 20-year-olds couldn’t drink — that’s why the distinction matters in legal language!

Common Mistakes

  • The most common mistake: treating 未満 and 以下 as the same. In legal/official contexts, they have very different implications.
  • Memory tip: 未 = “not yet” — so 未満 = “has not yet reached that number” = strictly less than.
  • In everyday casual speech, people sometimes use 以下 loosely to mean “under,” but in formal writing always check whether the boundary number is included or not.

Quick Quiz

Fill in: 未満 or 以下?

  • 1. 18歳___の方は入場できません。 (Those under 18 cannot enter — 18-year-olds cannot enter.)
  • 2. 料金は1,000円___です。 (The fee is 1,000 yen or less — 1,000 yen is acceptable.)
  • 3. 体重30kg___のお子様専用。 (For children weighing strictly under 30kg.)
  • 4. 気温5度___になると凍結注意。 (Caution for ice when temperature is 5 degrees or below.)

Answers: 1. 未満 2. 以下 3. 未満 4. 以下


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Summary

未満以下
Boundary number included?No — strictly less thanYes — up to and including
Think of it as“Has not yet reached X”“From X downward, X included”
Common contextLegal age limits, regulationsPrice ranges, temperature, scores
Opposite超える (exceeds)以上 (or more)
あわせて読みたい
以上 vs 以下: “Or More” vs “Or Less” in Japanese (Inclusive!) 以上 (ijou)以下 (ika)MeaningAbove / at least / or moreBelow / at most / or lessIncludes the number?Yes — X or above (X included)Yes — X or below ...
あわせて読みたい
Chigai vs Chigau Test Both 違い(ちがい) and 違う(ちがう) come from the same root and are often translated as "difference" or "to differ" in English. But learners frequently mi...
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