誕生日計算機

共有リンク

はじめに

Birthday Calculator — Days until your next birthday and the age you'll be turning. Enter Date of birth, As of (leave blank for today) to get an instant, accurate result.

計算式

Finds the next occurrence of your birth month/day from today (rolling to next year if this year's date has passed) and reports the days remaining and the age you'll be turning.

ステップごとの説明

Enter the Date of birth.
Enter the As of (leave blank for today).
Click Calculate to see your result instantly.

実例

Example: With Date of birth = 2000-01-15, the Birthday Calculator gives Days Until: 98, Next Birthday: 2027-01-15, Turning Age: 27.

よくある質問

What happens if I was born on February 29?

In non-leap years your birthday is treated as falling on February 28, so the countdown still works every year.

How is "turning age" calculated?

It's your age as of the next birthday date, one year more than your current age once that birthday arrives.

What inputs does the Birthday Calculator need?

You'll need to provide: Date of birth, As of (leave blank for today). All fields use sensible defaults, so you can see a working example immediately and then adjust the values to match your own numbers.

How accurate is the Birthday Calculator?

The Birthday Calculator applies the formula exactly as calculated — Finds the next occurrence of your birth month/day from today (rolling to next year if this year's date has passed) and reports the days remaining and the age you'll be turning. — so results are precise for the inputs you provide. Accuracy depends on entering correct, realistic input values.

Is the Birthday Calculator free to use?

Yes, the Birthday Calculator is completely free, requires no signup, and runs instantly in your browser.