Why "30 days" for a month?

Months vary from 28 to 31 days. We use 30 for a quick rule of thumb. For calendar-accurate math, use the age calculator.

What about leap years?

The year unit is 365 days. For exact calendar arithmetic, including leap years, use a dedicated date difference calculator.

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Convert any time duration between milliseconds, seconds, minutes, hours, days, weeks, months, and years.

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Seconds

Minutes

Hours

Days

Weeks

Months (30 days)

Years (365 days)