Hours, days, weeks, years: every duration conversion, precise to the millisecond.
Time looks easy — until contracts bill in hours, projects run in weeks, and salaries quote annual figures while paychecks arrive monthly. Even the units argue: a "month" is 28 to 31 days, so converters use the 30.44-day average, and a year is 365.2425 days, hence leap years.
The converters below use exact averages where it matters and clean rounding where it doesn't, each with the formula shown and the mental math for quick planning.
Convert seconds to hours, days to weeks, weeks to years — with the averages done right. A month here is 30.44 days (the calendar-true mean), a year is 365.2425 days, so payroll estimates and project plans stay honest. Each page shows the exact factor and the quick math for deadlines, billing and countdowns.
Are these converters really free? Yes — unlimited, no account, no paywall. CalculUnits is funded by non-intrusive ads only.
How accurate are the results? Every conversion uses the exact official factor from SI and NIST references, shown on each page so you can verify the math yourself.
Do my values leave my device? No — all calculations run in your browser. Nothing you type is ever sent anywhere.