Time Converter

From nanoseconds to years

This converter spans the full range of practical time units: nanoseconds, microseconds and milliseconds for computing, then seconds, minutes, hours, days and weeks for everyday use, plus months (30 days) and years (365 days) for longer spans.

It is perfect for performance benchmarks, project planning, and quick mental-math checks.

Common time conversions

• Hours to minutes and minutes to hours
• Days to hours and weeks to days
• Milliseconds to seconds for performance timing

Key features at a glance

• Spans nanoseconds, microseconds, and milliseconds for computing
• Covers seconds, minutes, hours, days, and weeks
• Includes months (30 days) and years (365 days) for longer spans
• Live conversion table updates as you type
• Useful for benchmarks, planning, and quick checks
• Runs entirely in your browser, even offline

Why some time units are exact and others are approximate

Most time conversions are perfectly exact because the units are defined by fixed ratios: a minute is always 60 seconds, an hour 3,600 seconds, a day 86,400 seconds. These never vary, so converting between seconds, minutes, hours, and days is precise to the last digit. The same is true at the small end, where milliseconds, microseconds, and nanoseconds are clean powers of ten below the second.

Months and years are different. Calendar months range from 28 to 31 days, and a year is 365 or 366 days depending on leap years. For a general converter, these are standardized to convenient averages — typically 30 days for a month and 365 days for a year — so the results are good approximations rather than calendar-exact figures. Knowing this distinction helps you trust the short-unit conversions completely while treating long spans as estimates.

Sub-second units and computing

Below the second lies a whole world of units that matter enormously in technology. A millisecond is a thousandth of a second, a microsecond a millionth, and a nanosecond a billionth. Human reaction time is a few hundred milliseconds, but computers operate far faster — modern processors execute instructions in nanoseconds, and network latency is measured in milliseconds.

These tiny units are essential for performance work. Web developers care whether a page responds in 100 or 500 milliseconds, and engineers profiling code measure functions in microseconds. Being able to convert between them, and up to seconds, makes benchmark figures intuitive: turning '2,500,000 nanoseconds' into '2.5 milliseconds' instantly clarifies how long something actually took.

How the second is defined

The second is the base unit of time in the International System of Units, and like the meter it is now defined by physics rather than astronomy. Originally a fraction of a day, it is today defined by the radiation of the caesium-133 atom — exactly 9,192,631,770 oscillations. Atomic clocks based on this definition are so stable they would lose less than a second over millions of years.

Every other time unit in this converter, from the nanosecond to the year, is ultimately built on that atomic second. This is why the conversions between fixed units are exact: they all reference the same precisely defined base. Leap seconds are occasionally added to keep clock time aligned with the slightly irregular rotation of the Earth, a reminder that even time has its subtleties.

Tips for converting time

• Fixed units (seconds to days) convert exactly; months and years are averaged
• Multiply seconds by 1,000 for milliseconds, by a million for microseconds
• There are 86,400 seconds in a day and 604,800 in a week
• Treat month and year conversions as estimates, not calendar-exact
• Use the date difference calculator for exact calendar spans

Why choose our time converter?

Our converter is completely free with no signup, no limits, and no subscription. It runs entirely in your browser, so conversions are instant, it works offline, and the values you enter never leave your device.

It is one of more than 200 free tools on ToopTools, and you can pin it to your My Workspace, a personalized workspace where you keep the tools you use most in a single dashboard. Beside the other unit converters and date tools, it covers every duration conversion in one place.

Common use cases

Developers and engineers use the time converter to make sense of performance figures, turning nanoseconds and microseconds into milliseconds and seconds. Project planners convert between hours, days, and weeks when scheduling, and students use it for physics and math problems involving durations.

People also use it for everyday questions — how many minutes in a day, how many hours in a week — and for converting timers, intervals, and durations between units. Because it shows every unit at once, a single value instantly reads across the whole range from nanoseconds to years.

Is the time converter free?

Yes. It is completely free with no account, no sign-up, and no usage limits. Convert as many durations as you like at no cost.

How many seconds are in a day?

There are exactly 86,400 seconds in a day — 24 hours times 3,600 seconds per hour. A week has 604,800 seconds. These fixed-unit conversions are exact, not approximate.

Why are month and year conversions approximate?

Because calendar months vary from 28 to 31 days and years can have 365 or 366 days. The converter uses standard averages — 30 days for a month and 365 for a year — so long-span results are estimates rather than calendar-exact.

What is a millisecond, microsecond, and nanosecond?

A millisecond is a thousandth of a second, a microsecond a millionth, and a nanosecond a billionth. They are used in computing and engineering, where events happen far faster than human perception.

Should I use this for exact calendar dates?

For exact spans between specific dates, use a date difference calculator, which accounts for actual month lengths and leap years. This converter is best for unit-to-unit duration conversion rather than calendar arithmetic.

Are my conversions kept private?

Yes. Everything is computed in your browser and nothing is uploaded, so the values you enter stay private and the tool works without an internet connection.

How do I convert hours to minutes and seconds?

Enter a value in hours and pick minutes or seconds as the target, and the converter shows the result instantly. It spans nanoseconds up to weeks and years, so you can switch between very small and very large time units in a single step.

Does the time converter work offline?

Yes. The conversion runs entirely in your browser, so once the page has loaded the tool works without an internet connection, and nothing you enter is uploaded — it stays private on your own device.