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Birthday Calculator

Find age in calendar years, months and days, total days lived and the next birthday for a selected reference date.

Your inputs

Dates
YOUR RESULT

Calendar age

31 years, 4 months, 18 days
Total days lived
11,463
Days until next birthday
225
Next birthday
2027-06-15
Completed years
31
Calculation method & assumptions

Uses calendar anniversaries in UTC, not an average year length. A 29 February birthday is observed on 28 February in non-leap years.

Dates have no time-of-day component. The reference date can be changed.

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HOW IT WORKS

Three steps. Ready for what’s next.

01

Enter your inputs

Use the labelled fields and select the assumptions or dates that apply to your calculation.

02

Review the result

Results update as inputs change. Check the breakdown, calculation method and assumptions.

03

Copy or download

Copy a summary or download the calculation breakdown as a CSV.

About Birthday Calculator.

How birthday is calculated

Uses calendar anniversaries in UTC, not an average year length. A 29 February birthday is observed on 28 February in non-leap years.

What the result means

Find age in calendar years, months and days, total days lived and the next birthday for a selected reference date.

Assumptions and scope

Dates have no time-of-day component. The reference date can be changed.

Using the calculator

Enter date of birth, calculate age on. Change the values to compare results. Calculations run in your browser. No account is required.

A LITTLE CLARITY

Good questions. Simple answers.

A few helpful answers before you get started.

Do I need an account?

No. This tool is open to everyone without signing in.

Does this tool need the internet?

Your inputs are calculated in this browser. Load the tool online before using it offline.

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