Femtosecond is 1e-15 second units.
Femtoseconds to Seconds Converter — fs to s
Convert Femtosecond (fs) to Seconds (s) using the exact conversion factor (1 femtosecond = 1e-15 seconds). See the formula, worked examples, conversion table, history, and common uses.
Femtoseconds to Seconds converter
Converter
Time Converter
Convert SI time, civil time, historical durations, months, and years.
Context values
Some unit families need one extra value for a physically accurate result.
The second is the SI base unit of time.
Result = input x 1e-15 / 1.
Months and years use the average Gregorian year.
Reserved above the conversion cards and below the converter.
About Converting Femtoseconds to Seconds
Femtosecond and Seconds are both everyday units of duration, and converting between them is one of the most routine calculations there is — scheduling, project planning, and billing all depend on it. Specifically: Femtosecond is 1e-15 second units, and the second is the SI base unit of time.
Formula
seconds = femtoseconds × 1e-15
This factor comes from each unit's defined relationship to the category's base unit: 1 femtosecond equals 1e-15 base units, and 1 seconds equals 1 base unit, so dividing one by the other gives the direct femtosecond-to-seconds factor of 1e-15.
Simple example
1 fs × 1e-15 = 1e-15 s
1 femtosecond = 1e-15 seconds.
Real-world example
24 fs × 1e-15 = 2.4e-14 s
24 femtoseconds = 2.4e-14 seconds.
Conversion table
| Femtosecond (fs) | Seconds (s) |
|---|---|
| 1 fs | 1e-15 s |
| 7 fs | 7e-15 s |
| 24 fs | 2.4e-14 s |
| 30 fs | 3e-14 s |
| 100 fs | 1e-13 s |
| 365 fs | 3.65e-13 s |
Reverse conversion: Seconds to Femtosecond
1e-15 s × 1e+15 = 1 fs
1e-15 seconds = 1 femtosecond.
femtoseconds = seconds × 1e+15
For a page dedicated to this direction, see Seconds to Femtosecond.
Understanding the Femtosecond (fs)
Femtosecond is 1e-15 second units.
Understanding the Seconds
Seconds (s) measures time. The second is the SI base unit of time, currently defined via a fixed number of cesium atomic transitions. It is classified as a SI base unit.
Where it's used: Universal
Uses of the Seconds today
- Fundamental unit for all timekeeping and scientific measurement
- Basis for derived units like speed (m/s) and frequency (Hz)
History of the Seconds
The second originated from dividing the day into 24 hours, each into 60 minutes, each into 60 seconds — a sexagesimal (base-60) system inherited from Babylonian astronomy. Since 1967, the second has been defined atomically, as exactly 9,192,631,770 periods of radiation from a cesium-133 transition, decoupling timekeeping from the Earth's slightly irregular rotation.
Historical origin. Seconds was not the invention of a single named person; it developed through the process described above.
Seconds — sources
- BIPM — The second (SI base unit) — Current atomic definition and history of the second.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many seconds are in 1 femtosecond?
1 femtosecond equals 1e-15 seconds, using the exact defined conversion factor rather than an estimate.
How do I convert femtosecond to seconds?
Multiply the femtosecond value by 1e-15. The converter above does this instantly to whatever precision you set.
How do I convert seconds back to femtosecond?
Use the reverse factor: 1 seconds equals 1e+15 femtoseconds. You can also use the swap control in the converter above to flip the direction instantly.
What is a femtosecond?
Femtosecond (fs) is a unit of time.
What is a seconds?
Seconds (s) measures time. The second is the SI base unit of time, currently defined via a fixed number of cesium atomic transitions. It is classified as a SI base unit.
Is the femtosecond to seconds conversion exact?
Yes. Both femtosecond and seconds are defined by fixed standards rather than physical artifacts, so the factor of 1e-15 used above is exact to as many digits as you choose to display.