This page converts femtoseconds into milliseconds using the factor 1.000000000e-12, and shows the reverse figure alongside it. Both units measure time, which is why one number does the whole job.
One thousandth of a second — the unit of network ping and reaction time. One quadrillionth of a second, the timescale of chemical bonds breaking.
Months and years are not fixed. This page uses the average Gregorian month of 30.44 days and the Julian year of 365.25 days, which is right for durations and wrong for calendars: three months from 31 January is not 91.31 days in any useful sense. Use a date calculator for calendar arithmetic. Two tables follow: rounded steps for quick lookup, and a set of real reference quantities converted into milliseconds, which is usually more useful than the bare number.
The formula
femtoseconds- The amount you are converting, in femtoseconds
1.00000000000e-12- The exact number of milliseconds in one femtosecond
milliseconds- The converted result
How it works, step by step
- Enter the value in femtoseconds.
- It is multiplied by 1.00000000000e-12, the exact factor between the two units.
- The answer is shown in milliseconds, with the reverse conversion beneath it.
- Check the reference table if you want a figure of comparable size.
Worked examples
A round figure: 1 fs in milliseconds
A round figure comes to about 1 fs. Multiplying by the factor: 1 × 1.00000e-12 = 1.00000e-12 ms. Dividing the answer back by 1.00000e-12 returns the figure you started with, which is the quickest way to check you have the factor the right way up.
A larger figure: 100 fs in milliseconds
At 100 fs (a larger figure), the same quantity in milliseconds is 100 × 1.00000e-12 = 1.00000e-10 ms. One femtosecond is 1.00000e-12 milliseconds, so the numbers shrink as expected.
How to read your score
Frequently asked questions
How many milliseconds are in one femtosecond?
Exactly 1.00000000000e-12. Every figure on this page is that one number multiplied by your input, so the only rounding is at the display step.
What is the formula to convert femtoseconds to milliseconds?
milliseconds = femtoseconds × 1.00000000000e-12. Reversed, femtoseconds = milliseconds ÷ 1.00000000000e-12, which is the same as multiplying by 1e+12.
Which is the bigger unit, the femtosecond or the millisecond?
The millisecond. One femtosecond is only 1.00000e-12 of a millisecond, so it takes 1e+12 femtoseconds to make one millisecond.
What does this quantity actually measure?
Both units measure time. That is why a single factor is enough: there is no temperature offset and no material property involved, unlike conversions that cross between different quantities.
What is a femtosecond?
One quadrillionth of a second, the timescale of chemical bonds breaking.
What is a millisecond?
One thousandth of a second — the unit of network ping and reaction time.
Why does my answer differ from another converter?
Almost always because the other tool rounded the factor before multiplying. This page keeps full double precision through the calculation and rounds only for display, and it prints the factor it used so you can see where any difference came from.
Femtoseconds to milliseconds reference tables
| Femtoseconds | Milliseconds |
|---|---|
| 0.5 fs | 5.00000e-13 ms |
| 1 fs | 1.00000e-12 ms |
| 2 fs | 2.00000e-12 ms |
| 3 fs | 3.00000e-12 ms |
| 5 fs | 5.00000e-12 ms |
| 10 fs | 1.00000e-11 ms |
| 20 fs | 2.00000e-11 ms |
| 25 fs | 2.50000e-11 ms |
| 50 fs | 5.00000e-11 ms |
| 75 fs | 7.50000e-11 ms |
| 100 fs | 1.00000e-10 ms |
| 250 fs | 2.50000e-10 ms |
| 500 fs | 5.00000e-10 ms |
| 1000 fs | 1e-09 ms |
| 5000 fs | 5e-09 ms |
Exact factor: 1 femtosecond = 1.00000000000e-12 milliseconds.
| Quantity | fs | ms |
|---|---|---|
| A camera flash | 1e+12 fs | 1 ms |
| A heartbeat | 8.57e+14 fs | 857 ms |
| A pop song | 2.100e+17 fs | 2.1e+05 ms |
| A working day | 2.880e+19 fs | 2.88e+07 ms |
| A pregnancy | 2.419e+22 fs | 2.419e+10 ms |
| A mortgage term | 7.574e+23 fs | 7.574e+11 ms |
Published reference values, converted with the same factor this page uses.