Axis

Length & distance

femtometrefm

Femto-scaled variant of the metre, exactly fm = 0.000000000000001 base unit.

Dimension
length
Canonical signature
L
System
si
Exactness
Exact

Definition record

How this unit is defined

Canonical base
1 fm = 1e-15 m
Conversion type
linear
Historical notes
Defined through the fixed speed of light in vacuum, 299 792 458 m/s.
Aliases
femto meter, femto meters, femto m in length context

Same dimension

Related units

metresiminchimperial usinfootimperial usftmileimperial usmiyardimperial usydlight-yearastronomicallypixelcsspxnanometresinm

Common conversions

Every conversion routes through the canonical base of the dimension.

1 fm = 1e-15 m

Exact relationship

10 fm = 1e-14 m

Exact relationship