How this calculator works
The entered value is multiplied by its unit length to get a number of seconds. Dividing that same second count by each unit length gives every other row of the table. The conversions are exact for the fixed unit lengths used here, which is why the table is a set of reversals of one another rather than seven independent roundings.
Formula
seconds = amount x length of the chosen unit. Each other value = seconds / length of that unit. The lengths are 1 s, 60 s, 3600 s, 86400 s, 604800 s, 2629800 s (30.4375 days) for a month and 31557600 s (365.25 days) for a year.
Worked example
One year is 31557600 seconds. The same span is 525960 minutes, 8766 hours, 365.25 days, 52.178571 weeks or 12 months. Entering 12 months gives the same second count back.
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Frequently asked questions
Why does a month use 30.4375 days?
That is an average calendar month over a full four-year cycle, so a year of twelve months is exactly 365.25 days. Real calendar months vary from 28 to 31 days, which is why date arithmetic should use dates rather than a fixed month length.
Why does a year use 365.25 days?
It is the mean Julian year, the standard length used for converting between years and days. A real Gregorian year is 365 or 366 days, so a conversion involving calendar dates can differ by a day.
What does reverse mean here?
It reverses the usual order of a conversion: instead of taking a time and asking for one unit, it takes one unit and shows the time in every other unit at once. It does not run time backward.
Can I convert months to weeks exactly?
Not in calendar terms, because months are not a whole number of weeks. The table uses the average lengths above, so treat months and years as averages rather than calendar counts.