Time Converter
Time converter — milliseconds up to years.
Convert between milliseconds, seconds, minutes, hours, days, weeks, months and years. The page explains how months and years are averaged, which is the main source of confusion in time conversion.
Popular Time Conversions
- Hour to Minute
- Day to Hour
- Hour to Month (average)
- Month (average) to Hour
- Day to Minute
- Year (Julian) to Day
- Week to Day
- Year (Julian) to Month (average)
- Minute to Second
- Hour to Second
- Month (average) to Day
- Week to Hour
All Time Units
| Unit | Symbol | Definition |
|---|---|---|
| Millisecond | ms | One thousandth of a second. |
| Second | s | The SI base unit of time, defined by a fixed number of cesium atom oscillations. |
| Minute | min | Equal to 60 seconds. |
| Hour | hr | Equal to 60 minutes. |
| Day | day | Equal to 24 hours, approximating one rotation of the Earth. |
| Week | wk | Equal to 7 days. |
| Month (average) | mo | Approximated here as 1/12 of a Julian year, since calendar months vary in length. |
| Year (Julian) | yr | Defined here as 365.25 days, the standard Julian year used in scientific contexts. |
How time conversion works
The second is the SI base unit of time. Since 1967 it has been defined as 9,192,631,770 periods of the radiation of the caesium-133 atom. Larger units are built from it:
1 hour = 60 min = 3,600 s
1 day = 24 h = 86,400 s
1 week = 7 days = 604,800 s
1 average month = 30.4375 days = 730.5 hours
1 Julian year = 365.25 days = 31,557,600 s
Days, hours, minutes and seconds are exact. Months and years are not fixed: calendar months range from 28 to 31 days, and years from 365 to 366. This converter uses the average month (365.25 ÷ 12 = 30.4375 days) and the Julian year (365.25 days), which is correct for long-run averages but not for a specific calendar month.
Quick reference
| Unit | In smaller unit | In another unit |
|---|---|---|
| 1 hour | 60 min | 3600 s |
| 1 day | 24 h | 1440 min |
| 1 week | 7 days | 168 h |
| 1 average month | 30.4375 days | 730.5 h |
| 1 year | 365.25 days | 8766 h |
| 1 year | 52.1786 weeks | 12 months |
Hours to months, and hourly pay to monthly pay
An average month has 730.5 hours. For work and pay, however, people usually mean working hours, not all hours in a month:
- A standard 40-hour week × 52 weeks ÷ 12 months = 173.33 working hours per month.
- An hourly rate of 1,000 for a 40-hour week is roughly 1,000 × 173.33 = 173,330 per month before tax and unpaid leave.
- A 48-hour working week (common in some industries) is 48 × 52 ÷ 12 = 208 hours per month.
For payroll, use the contract's rule, not the average-month figure on this page.
Where each unit is used
- Milliseconds: website speed, computing, audio and sports timing.
- Seconds, minutes, hours: everyday time, cooking, travel and billing.
- Days and weeks: delivery estimates, project plans and medical courses.
- Months and years: loans, rent, subscriptions, ages and planning. Check whether a contract uses calendar or average months.
Common mistakes to avoid
- Treating a month as 30 days. The average is 30.44 days, and 12 × 30 = 360 days leaves out 5 days a year.
- Forgetting leap years. A calendar year has 365 days, or 366 in a leap year. The Julian year of 365.25 days is an average.
- Decimal hours vs minutes. 1.5 hours is 1 hour 30 minutes, not 1 hour 50 minutes. Multiply the decimal part by 60.
- Time zones and daylight saving. A duration in hours is not the same as a clock-time difference across time zones.
Exact conversion factors
| Unit | Symbol | Exact factor |
|---|---|---|
| Millisecond | ms | 1 ms = 0.001 s |
| Second | s | 1 s = 1 s |
| Minute | min | 1 min = 60 s |
| Hour | hr | 1 hr = 3600 s |
| Day | day | 1 day = 86400 s |
| Week | wk | 1 wk = 604800 s |
| Month (average) | mo | 1 mo = 2629800 s |
| Year (Julian) | yr | 1 yr = 31557600 s |
Sources: BIPM, The International System of Units (SI Brochure); the Julian year is defined as 365.25 days of 86,400 s.
Frequently Asked Questions
How many hours are in a month?
An average month has 730.5 hours (30.4375 days × 24). A 30-day month has 720 hours and a 31-day month has 744 hours.
How many seconds are in a day?
There are 86,400 seconds in a day (24 × 60 × 60).
How many days are in a year?
A common year has 365 days and a leap year has 366. The average Julian year is 365.25 days.
How many minutes are in a week?
A week has 10080 minutes (7 × 24 × 60).
How do I convert hours to minutes?
Multiply hours by 60. For example 2.5 hours = 150 minutes.
How many working hours are in a month?
On a 40-hour week, about 173.3 hours per month (40 × 52 ÷ 12).
How many weeks are in a month?
An average month is 4.3482 weeks (30.4375 ÷ 7).
All Time Conversions
Choose a starting unit to see every conversion available from it.