Quick answer
Time units convert through seconds. 1 day equals 24 hours, 1,440 minutes or 86,400 seconds.
Enter a value and choose the units. The calculator returns the converted duration.
Related tools: Time Duration Calculator: Elapsed time between two clock times, including across midnight. Time Card Calculator: Total hours, overtime and gross pay from daily start and end times. Download Time Calculator: Time to download a file at a given speed.
How to use the Time Converter
- Enter value.
- Choose from: Nanosecond (ns), Microsecond (µs), Millisecond (ms), Second (s), Minute (min) and Hour (h) and 6 more.
- Choose to: Nanosecond (ns), Microsecond (µs), Millisecond (ms), Second (s), Minute (min) and Hour (h) and 6 more.
- Enter decimal places (between 0 and 10). It starts at 4.
- Press Calculate to see the result, and use Reset to start again.
| Input | What to enter | Allowed values |
|---|---|---|
| Value | A number | — |
| From | Choose one: Nanosecond (ns); Microsecond (µs); Millisecond (ms); Second (s); Minute (min); Hour (h); Day (d); Week (wk); … | Starts at Nanosecond (ns) |
| To | Choose one: Nanosecond (ns); Microsecond (µs); Millisecond (ms); Second (s); Minute (min); Hour (h); Day (d); Week (wk); … | Starts at Microsecond (µs) |
| Decimal places | A number | ≥ 0, ≤ 10, starts at 4 |
Formula and method
Formula
result = value × (factor of source ÷ factor of target), base unit: second
IEEE-754 double precision; displayed to the chosen number of decimal places (default 4). Very small or large results are shown in scientific notation.
Every unit is defined by an exact or published factor to the base unit (second). The value is multiplied by the source factor and divided by the target factor. Month and year use the mean Gregorian values (30.436875 and 365.2425 days); calendar months vary.
Worked examples
These examples are verified: each one is an automated test case that the live calculator must reproduce exactly.
Example 1
Inputs: Value = 1; From = Day (d); To = Hour (h); Decimal places = 4.
| Result | Value |
|---|---|
| Day (d) → Hour (h) | 24 |
| Input | 1 Day (d) |
Example 2
Inputs: Value = 1; From = Week (wk); To = Day (d); Decimal places = 4.
| Result | Value |
|---|---|
| Week (wk) → Day (d) | 7 |
| Input | 1 Week (wk) |
Example 3
Inputs: Value = 90; From = Minute (min); To = Hour (h); Decimal places = 4.
| Result | Value |
|---|---|
| Minute (min) → Hour (h) | 1.5 |
| Input | 90 Minute (min) |
The first line is the headline result (day (d) → Hour (h)). Below it the time Converter lists input, which describe the same case from other angles. IEEE-754 double precision; displayed to the chosen number of decimal places (default 4). Very small or large results are shown in scientific notation.
Unit reference
Each unit expressed in the base unit used for the calculation. Conversions go through this base unit, so any unit can be converted to any other in the table.
| Unit | Equals (in second) |
|---|---|
| Nanosecond (ns) | 1e-9 |
| Microsecond (µs) | 0.000001 |
| Millisecond (ms) | 0.001 |
| Second (s) | 1 |
| Minute (min) | 60 |
| Hour (h) | 3600 |
| Day (d) | 86400 |
| Week (wk) | 604800 |
| Month (mean Gregorian) | 2629746 |
| Year (mean Gregorian) | 31556952 |
| Decade | 315569520 |
| Century | 3155695200 |
Fixed and variable units
Seconds, minutes, hours, days and weeks have fixed lengths here: a week is 7 days. Months and years vary, so converters use averages, such as 30.44 days per month and 365.25 days per year.
Quick values
1 hour = 3,600 s, 1 week = 604,800 s and 1 year ≈ 31.56 million s. For calendar-exact differences between two dates, use the date calculators.
How the result changes with value
Holding every other input at the first worked example, this table changes only value. It shows how sensitive the answer is to that one value; each row was produced by running this calculator.
| Value | Day (d) → Hour (h) | Input |
|---|---|---|
| 0.5 | 12 | 0.5 Day (d) |
| 1 | 24 | 1 Day (d) |
| 2 | 48 | 2 Day (d) |
| 4 | 96 | 4 Day (d) |
What happens with invalid input
These messages are produced by the calculator itself, so you know what to fix.
- Value: left empty shows "Enter value." beside that field and no result.
Choosing between the Time Converter and similar calculators
Each row shows what a related calculator on this site asks for and what it returns, so you can pick the one that matches your question.
| Calculator | You enter | It returns |
|---|---|---|
| [Time Duration Calculator](/time/time-duration-calculator/) | start time and end time | Duration |
| [Time Card Calculator](/time/time-card-calculator/) | start times, end times and unpaid break per day | Total time |
| [Download Time Calculator](/technology/download-time-calculator/) | file size, size unit and connection speed | Time |
| [Time From Now Calculator](/time/minutes-from/) | start time and minutes to add | Resulting time |
| [Time Until Calculator](/time/time-until-calculator/) | current time and target time | Time remaining |
Background: unit conversion
Many customary units are defined exactly in terms of metric ones: since the 1959 International Yard and Pound Agreement an inch is exactly 2.54 cm and a pound is exactly 0.45359237 kg (NIST SP 811 lists these). So most length and mass conversions are exact apart from the rounding of the displayed result.
To convert, multiply the value by the source unit's factor to reach the base unit, then divide by the target unit's factor; the unit table on this page lists every factor used. Temperature and fuel economy are the exceptions, because they are not simple multiples.
Assumptions and limitations
- Negative values are allowed
- Zero converts to zero (except L/100 km, where zero is invalid)
- Units from different quantities cannot be converted
- Very large or tiny results switch to exponent notation
If a required value is empty, not a number, or outside its allowed range, the form marks that field with a message and shows no result instead of a misleading number. The automated checks deliberately try invalid entries for value to confirm this.
Frequently asked questions
How many seconds in a day?
There are 86,400 seconds in a day.
How many hours in a week?
A week has 7 × 24 = 168 hours; convert 1 week to hours to confirm.
Does it handle leap seconds?
No. The time units are fixed lengths, so leap seconds, which are occasionally added to UTC, are not modelled.
What does the Time Converter calculate?
Convert seconds, minutes, hours, days, weeks, months and years. It returns Day (d) → Hour (h) and Input.
What formula does the Time Converter use?
result = value × (factor of source ÷ factor of target), base unit: second. Every unit is defined by an exact or published factor to the base unit (second).
What is an example of a time result?
With value 1, from Day (d), to Hour (h) and decimal places 4, the day (d) → Hour (h) is 24.
Where does the method come from?
The method follows: BIPM SI Brochure (9th ed.): second; Gregorian calendar mean year = 365.2425 days.
Related calculators
- Time Duration Calculator — Elapsed time between two clock times, including across midnight.
- Time Card Calculator — Total hours, overtime and gross pay from daily start and end times.
- Download Time Calculator — Time to download a file at a given speed.
- Time From Now Calculator — Clock time after adding or subtracting minutes.
- Time Until Calculator — Hours and minutes from the current time until a target clock time (generalizes “how long until 3:58 PM”).
- Military Time Converter — Convert between 24-hour (military) time and 12-hour AM/PM time.
- Battery Charge Time Calculator — Hours to charge a battery from a charger current.
Sources
- BIPM SI Brochure (9th ed.): second
- Gregorian calendar mean year = 365.2425 days
Content last reviewed 2026-11-04. Formulas and worked examples are checked by automated tests against independently computed values.