Time Converter — Free Online Time Unit Converter
Our free time converter instantly converts between all major time units. Use the time converter to switch between seconds, minutes, hours, days, weeks, months, years and more — no sign-up required. This time converter uses exact SI-defined conversion factors for every unit pair. Learn more at Wikipedia's unit of time reference and the NIST unit conversion guide.
⏱️ Time Converter
Popular Time Conversions
Select any pair — the converter above handles all 15 time units instantly.
All conversions handled by the single widget above — just select your units from the dropdowns.
Quick Reference Tables
Common time values converted at a glance.
Seconds → Minutes & Hours
| Seconds | Minutes | Hours |
|---|---|---|
| 60 | 1 | 0.0167 |
| 300 | 5 | 0.0833 |
| 600 | 10 | 0.1667 |
| 900 | 15 | 0.25 |
| 1,800 | 30 | 0.5 |
| 3,600 | 60 | 1 |
| 7,200 | 120 | 2 |
| 18,000 | 300 | 5 |
| 36,000 | 600 | 10 |
| 86,400 | 1,440 | 24 |
Hours → Days & Weeks
| Hours | Days | Weeks |
|---|---|---|
| 1 | 0.0417 | 0.006 |
| 6 | 0.25 | 0.0357 |
| 12 | 0.5 | 0.0714 |
| 24 | 1 | 0.1429 |
| 48 | 2 | 0.2857 |
| 72 | 3 | 0.4286 |
| 168 | 7 | 1 |
| 336 | 14 | 2 |
| 720 | 30 | 4.286 |
| 8,760 | 365 | 52.14 |
Days → Months & Years
| Days | Months | Years |
|---|---|---|
| 1 | 0.0329 | 0.00274 |
| 7 | 0.2299 | 0.01916 |
| 30 | 0.9856 | 0.08213 |
| 60 | 1.971 | 0.1643 |
| 90 | 2.957 | 0.2464 |
| 180 | 5.914 | 0.4929 |
| 365 | 11.99 | 1 |
| 730 | 23.97 | 2 |
| 1,825 | 59.94 | 5 |
| 3,650 | 119.9 | 10 |
Conversion Formulas
The exact math behind every time unit conversion.
Understanding Time Units
The SI Base Unit — The Second
The second (s) is the SI base unit of time and the foundation of all other time conversions. It is defined by the International System of Units as exactly 9,192,631,770 cycles of the radiation corresponding to the transition between two energy levels of the caesium-133 atom — making it one of the most precisely defined units in all of science.
All other time units — milliseconds, minutes, hours, days — are derived from the second by multiplying or dividing by exact integer factors, making time conversions among the most straightforward of any unit category.
Minutes, Hours & Days — Everyday Time
The minute (60 seconds), hour (3,600 seconds), and day (86,400 seconds) are the units people use most in daily life — scheduling, work, travel, and sleep are all measured in these. Their 60-based and 24-based relationships are ancient, rooted in Babylonian mathematics.
One full day equals exactly 24 hours, 1,440 minutes, or 86,400 seconds. These are clean, exact relationships — no rounding needed. Our converter uses these exact integers for maximum precision.
Weeks, Months & Years — Calendar Time
A week is exactly 7 days (604,800 seconds). Beyond that, calendar units get less exact. A month ranges from 28 to 31 days; our converter uses the average Gregorian month of 30.4369 days (365.2425 ÷ 12). A year uses the Gregorian average of 365.2425 days to account for leap years.
This is why the month and year conversions show non-round numbers — they reflect the real astronomical complexity of the calendar rather than a simplified approximation.
Sub-Second & Extended Units
For precision work in science and technology, our converter also handles milliseconds (1/1,000 s), microseconds (1/1,000,000 s), and nanoseconds (1/1,000,000,000 s) — units used in electronics, physics, and computer science.
At the other extreme, it supports decades (10 years), centuries (100 years), millennia (1,000 years), fortnights (14 days), and quarters (3 months) — covering every unit from nanoseconds to millennia in a single tool.
Frequently Asked Questions
There are exactly 86,400 seconds in one day. This comes from 24 hours × 60 minutes × 60 seconds = 86,400 s. It's one of the most useful time conversions for programming, physics, and scheduling calculations.
One Gregorian year equals 31,556,952 seconds, based on an average year of 365.2425 days (accounting for leap years). A common approximation is 31,536,000 seconds (365 × 86,400), though this doesn't account for leap years.
There are exactly 168 hours in one week (7 days × 24 hours). This is a commonly needed conversion for work scheduling, payroll, and project planning — for example, a 40-hour work week represents just under 24% of all the hours in a week.
Calendar months range from 28 to 31 days. For conversion purposes, our converter uses the average Gregorian month of 30.4369 days (365.2425 days ÷ 12 months). If you need an exact count for a specific month, use a calendar — January has 31 days, February has 28 or 29, and so on.
A fortnight is exactly 14 days, or two weeks (1,209,600 seconds). The term is common in British English and some Commonwealth countries, often used in contexts like payroll cycles or rental agreements. Our converter includes fortnight as a selectable time unit.
Months and years don't have a fixed number of days, so the converter uses astronomically precise averages: 1 year = 365.2425 days (the Gregorian calendar average), and 1 month = 365.2425 ÷ 12 = 30.4369 days. This gives results accurate enough for all practical purposes while correctly reflecting the real length of the calendar year.