Time Conversion Calculator
Convert between twelve units of time, from nanoseconds to centuries, in one step. Enter a value, pick your from and to units, and the tool converts instantly. It also renders your result in every other unit at the same time, so one input answers every follow-up question.
Enter a number greater than or equal to 0.
| Unit | Your value equals |
|---|
Months and years use fixed averages (1 month = 30.4375 days, 1 year = 365.25 days), so they do not track any specific calendar month or leap year. Leap seconds are not included.
How the conversion works
Formula: converted value = input value × (seconds per from-unit ÷ seconds per to-unit).
Every unit is defined by a single exact factor relative to the second: 1 minute = 60 seconds, 1 hour = 3,600 seconds, 1 day = 86,400 seconds, 1 week = 604,800 seconds. The tool multiplies your value into seconds, then divides by the target unit’s factor. Because the whole calculation runs through one common base, there is no rounding drift between units: converting hours to minutes and then minutes to seconds gives exactly the same answer as converting hours to seconds directly.
Worked example, verified against the tool
Convert 2 hours to minutes. Seconds per hour = 3,600, seconds per minute = 60. So 2 × (3,600 ÷ 60) = 2 × 60 = 120 minutes. The tool shows exactly this, plus the same 2 hours expressed in every other unit: 7,200 seconds, 0.0833 days, 0.0119 weeks, 7,200,000 milliseconds.
A second check: 100,000 seconds to days = 100,000 ÷ 86,400 = 1.1574 days, matching the tool output. Both examples were run through the live calculator code and confirmed.
The honest part: months and years are averages
Seconds, minutes, hours, days, and weeks are exact by definition. Months and years are not: February has 28 or 29 days, and a year can be 365 or 366 days. This tool uses the standard averages, 1 month = 30.4375 days (365.25 ÷ 12) and 1 year = 365.25 days, and labels them as averages in the dropdown so nobody mistakes them for calendar-exact values. If your calculation depends on a specific month or a leap year, convert with days instead and pick the exact day count yourself.
Common conversions at a glance
| From | To | Multiply or divide by |
|---|---|---|
| Minutes | Seconds | × 60 |
| Hours | Minutes | × 60 |
| Days | Hours | × 24 |
| Weeks | Days | × 7 |
| Seconds | Milliseconds | × 1,000 |
| Hours | Seconds | × 3,600 |
Frequently asked questions
How many seconds are in a day?
86,400. That is 24 hours × 60 minutes × 60 seconds. A week is 7 × 86,400 = 604,800 seconds.
Why does the tool say months are approximate?
Because real months range from 28 to 31 days. The tool uses the astronomical average of 30.4375 days per month (365.25 ÷ 12), which is the standard convention for unit converters. For exact date math, use days and count the specific month.
Can I convert decimal values like 2.5 hours?
Yes. Enter 2.5 hours and select minutes: 2.5 × 60 = 150 minutes. Decimals work in both directions.
Does the calculator handle milliseconds and microseconds?
Yes, down to nanoseconds. These matter in computing, electronics, and physics, where a millisecond (0.001 s), microsecond (0.000001 s), and nanosecond (0.000000001 s) are everyday units.
Why is there no timezone conversion here?
This tool converts durations (how long something lasts), not clock times across timezones. Converting 3 hours to minutes is a different job from converting 3 PM New York time to London time.
Is the conversion exact?
For seconds through weeks, yes, exact by definition. For months, years, decades, and centuries, the result is exact relative to the stated averages (365.25-day year), which the tool discloses above the results.