Precise time-unit conversion

Time Converter

Convert tiny scientific time units and everyday durations instantly. Compare every result, build compound durations, control rounding and see clearly how average months and years are defined.

Time Unit Converter

Enter a value and choose the source and target units. The complete conversion table updates automatically.

Conversion result

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Conversion formula–

Equivalent in seconds–

Time-unit magnitude scale

The logarithmic scale shows how far apart the selected units are, from a nanosecond to a decade.

nsdec

All time units at a glance

Select any row to make it the target unit.

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Compound duration converter

Enter a compact duration such as 2h 35min 20s. Use y / mo / w / d / h / min / s / ms / µs / ns.

Normalized duration–

Total seconds–

Fixed units and calendar units

Nanoseconds through weeks have fixed relationships. Calendar months and years vary in actual length, so converting them without a start date requires a documented average.

The SI second

The second is the SI base unit of time. Smaller and larger metric units use powers of ten, while minutes, hours, days and weeks use conventional fixed ratios.

Months and years are average units

This unit converter uses the mean Gregorian year of 365.2425 days and one twelfth of that year for a month, or 30.436875 days. For an exact calendar interval, use the Time Duration Calculator with real dates.

Practical conversion examples

2.5 hours equals 150 minutes or 9,000 seconds.
500 milliseconds equals 0.5 seconds.
One average Gregorian year equals 365.2425 days or 31,556,952 seconds.

Definition and reference

The scientific definition of the second follows the BIPM SI Brochure. Month and year conversions on this page use the clearly stated Gregorian averages above.

Time converter FAQ

How many seconds are in one hour?

One hour contains exactly 3,600 seconds.

How many milliseconds are in one second?

One second contains exactly 1,000 milliseconds.

Is a month always 30.436875 days?

No. That is the mean Gregorian month used for unit conversion. A real calendar month can contain 28, 29, 30 or 31 days.

Why can year conversions differ between websites?

Some converters use 365 days, while this converter uses the mean Gregorian year of 365.2425 days and states that assumption explicitly.

Can I enter several time units together?

Yes. The compound converter accepts combinations such as 1d 4h 30min and returns a normalized duration and total seconds.

Does the calculator store my values?

No. The conversion runs locally in your browser, and the page only places values in the URL when you choose to copy a shareable link.