Time Converter
Milliseconds through years — with month and year clearly marked as calendar averages, not fixed lengths.
Common conversions
Time unit reference
What 1 day equals in every other unit.
| Unit | Value |
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Why "month" and "year" here are averages, not fixed numbers
Every other unit on this page is exact: a minute is always 60 seconds, a day is always 24 hours, full stop. Months and years genuinely aren't like that. A month is 28, 29, 30, or 31 days depending which one, and a year is 365 days — except every 4th year, when it's 366, except century years, unless they're divisible by 400. There's no single "correct" number of days in a month or year to convert with, because the calendar itself doesn't have one.
So this converter uses the Gregorian calendar average: 365.2425 days per year, which is the actual long-run average built into the modern calendar's leap year rule (a leap year every 4 years, skipped on century years, except when divisible by 400 — which nets out to 97 leap years every 400 years). The average month here is simply that average year divided by 12, giving 30.436875 days — not any specific real month, but the mathematically consistent middle ground.
This is precise enough for most everyday and financial purposes (estimating an age in seconds, converting an average monthly rate to yearly, and similar), but if you need the exact number of days in a specific calendar month or a specific year, that's a calendar lookup, not a unit conversion — no fixed factor can give you that, since the honest answer depends on which month or year you mean.