Enter a length of time, pick the unit you have and the unit you want, and read the result instantly — along with the same duration in every other unit at once. It covers the exact units (seconds up to weeks) and the two approximate ones (month and year) people reach for when planning schedules, timeouts and deadlines. Everything runs in your browser.
In all units
- Millisecond (ms)3,600,000 ms
- Second (s)3,600 s
- Minute (min)60 min
- Hour (h)1 h
- Day (d)0.041667 d
- Week (wk)0.005952 wk
- Month (avg)0.001369 mo
- Year (avg)0.000114 yr
How it works
Each unit is defined by how many seconds it equals, and every conversion goes through the second as a shared base. The short units are exact by definition: a minute is 60 seconds, an hour 3,600, a day 86,400, a week 604,800. Your value is turned into seconds and then into the target unit.
Months and years are averages, because real ones vary. This tool uses the Julian year of 365.25 days (31,557,600 seconds) and defines a month as that year divided by twelve — about 30.44 days. So "3 months" here means roughly 91.3 days, not a specific calendar span. For exact calendar arithmetic between two real dates, use a date-difference tool instead.
Practical examples
A timeout in minutes to seconds
A 90-minute session timeout is 5,400 seconds — the value a config file usually wants. Enter 90, from minutes, to seconds.
Project length in days to weeks
A 45-day task is about 6.43 weeks. Convert days to weeks to describe a timeline in whole-ish weeks for a plan or standup.
How many hours in a year
One average year is 8,766 hours (365.25 × 24). Convert years to hours to sanity-check a "hours per year" figure like available working time.
Frequently asked questions
How many seconds are in an hour?
Exactly 3,600 — that is 60 minutes of 60 seconds each. A day is 86,400 seconds and a week is 604,800. These short units are exact by definition, so their conversions are precise.
How long is a month in this tool?
A month here is the average calendar month: one Julian year (365.25 days) divided by 12, which is about 30.44 days or 2,629,800 seconds. It is a planning approximation, not a specific month like February.
Why is a year 365.25 days and not 365?
The quarter-day accounts for leap years (one extra day roughly every four years). Using 365.25 days keeps long durations from drifting — it is the Julian year, the standard average for this kind of conversion.
How do I convert minutes to hours?
Divide minutes by 60: 150 minutes is 2.5 hours. Enter the value in minutes and read the hour row — the tool does it and shows the other units too.
Can I use this to count days between two dates?
No — this converts a length of time between units, not the gap between two calendar dates. For that (which accounts for actual month lengths and leap years) use a days-between-dates tool.
Does it handle milliseconds?
Yes. One second is 1,000 milliseconds, so a 250 ms delay is 0.25 seconds. Milliseconds are useful for timing code and animations; the tool converts them to any other unit.
How precise are the results?
Conversions run at full floating-point precision and are shown to six decimals with trailing zeros trimmed. For exact units the results are exact; for month and year they inherit the average-length assumption above.
Does it accept the decimal comma?
Yes. You can type 1,5 or 1.5 and both mean one and a half. Grouping separators in pasted numbers are read too, so 3.600 is understood correctly.
Are the values I enter sent anywhere?
No. The conversion happens entirely in your browser; nothing is uploaded and analytics never receives the numbers you type.
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