# Time Unit Converter URL: https://speedycalculator.com/calculators/conversion/time-converter/ Last updated: 2026-10-25 > The time unit converter converts time between seconds, milliseconds, minutes, days, weeks, months and more. Choose any “from” and “to” unit, type a number into any field and every other unit updates instantly; all conversion factors are exact definitions. ## Inputs - From (h, s, ms, µs, ns, min, day, week, fortnight, month, year, decade, century, millennium) ## Results - To - Milliseconds - Minutes - Days - Weeks - Months - Years ## Formula ``` 1 h = 3,600 s 1 h = 3,600,000 ms 1 h = 60 min 1 h = 0.041666667 day 1 h = 0.005952381 week ``` ## Explanation Seconds, minutes and hours are exact multiples of each other, but months and years are not: this converter uses the average Gregorian month (30.436875 days) and year (365.2425 days), which is what you need for long periods and averages. ### How to use the Time Unit Converter - Pick the unit you are starting from in the **From** menu and type your value. - Pick the unit you want in the **To** menu. The heading changes to match – for example “Hours to Seconds Converter”. - The most common time units are shown below at the same time, so you can compare them at a glance. - Type into any result to convert backwards, then use **Copy results** – the copied text starts with the heading for your chosen units. Results update as you type. Everything is calculated in your browser. ### How it works Every time unit is defined by an exact factor relative to the second (the base unit). The calculator first turns the value you type into seconds, then turns that into the unit you picked in the “To” menu and into each of the common units below it. This two-step method means any unit can be converted to any other – 14 units are available in each menu – and you can type into any field, including a result, to work in the other direction. Changing a unit menu keeps the quantity the same and just re-expresses it, and the page heading and copied results follow your choice. ### How to convert time units - Choose the unit you have in the **From** menu and type the value, for example **2.5 h**. - Choose the unit you want in the **To** menu, for example seconds. The page heading changes to “Hours to Seconds Converter”. - The calculator multiplies by the second factor of the “from” unit and divides by the factor of the “to” unit: 2.5 h × 3,600 ÷ 1 = **9,000 s**. ### 1 hour in common units UnitValueSeconds (s)3,600Milliseconds (ms)3,600,000Minutes (min)60Days (day)0.041666667Weeks (week)0.005952381Months (month)0.0013689535Years (year)0.00011407946Decades (decade)1.140795 × 10-5 ### Hours conversion table Hourssmsminday0.51,8001,800,000300.02083333313,6003,600,000600.04166666727,2007,200,0001200.083333333828,80028,800,0004800.333333332486,40086,400,0001,440140144,000144,000,0002,4001.6666667168604,800604,800,00010,08071,0003,600,0003.6 × 10960,00041.666667 ### What is an hour? An hour is 60 minutes or 3,600 seconds. Wages, shifts and travel times are counted in hours. ### What is a second? The second is the SI base unit of time, defined by 9,192,631,770 cycles of radiation from a caesium-133 atom. ### What is a millisecond? A millisecond is one thousandth of a second. Network latency, reaction times and computer timers are measured in milliseconds. ### Common mistakes to avoid Treating every month as 30 days or every year as 365 days in long calculations, and writing decimal hours such as 1.5 h as 1 h 50 min (it is 1 h 30 min). ## Worked example Inputs — From: 2.5 h. Results — **To = 9,000 s**; Milliseconds = 9,000,000 ms; Minutes = 150 min; Days = 0.10416667 day; Weeks = 0.01488095 week; Months = 0.00342238 month; Years = 0.0002852 year. ## FAQ **How many seconds in a day?** 86,400. **Why is a month 30.44 days?** That is the average month length over the 400-year Gregorian cycle. **How many hours in a year?** 8,765.82 on average (8,760 in a 365-day year). **How do I change the units?** Pick any unit in the From and To menus. The value is converted in place, and the heading changes to show your conversion, for example “Hours to Seconds Converter”. **Can I type into any field?** Yes. Every field is editable, so you can start from whichever unit you have. **How many units can I convert between?** 14 time units, from the everyday to the specialised. **Which units are exact?** All factors here are exact by definition except astronomical and similar reference values, which use internationally agreed constants. **What formula does the Time Unit Converter use?** 1 h = 3,600 s. ## Sources - [NIST Special Publication 811 – Guide for the Use of the International System of Units](https://www.nist.gov/pml/special-publication-811) - [NIST Handbook 44 Appendix C – General tables of units of measurement](https://www.nist.gov/pml/owm/nist-handbook-44-current-edition)