Convert Femto to Atto

Femto (f) to Atto (a) SI prefix conversion — enter any value below to get an instant result, or use the table for common values.

Results from this calculator are estimates provided for general informational purposes only, based on formulas, rates, and standards commonly accepted as of 2026. Figures may differ slightly from other calculators or professional sources due to rounding methods, differing assumptions, or regional regulations, and rules may change over time. Always consult a qualified professional — such as a financial advisor, healthcare provider, or other relevant specialist — before making decisions based on these results.

Value

From

Result

1 f = 1000 a

1 Femto = 1000 Atto

1 Atto = 0.001 Femto

1 f in every supported prefix

Conversion chart: Femto to Atto

Conversion table

Femto (f)	Atto (a)
0.01 f	10 a
0.1 f	100 a
1 f	1000 a
2 f	2000 a
3 f	3000 a
5 f	5000 a
10 f	10000 a
20 f	20000 a
50 f	50000 a
100 f	100000 a
1000 f	1000000 a

Femto (f)

Definition: An SI prefix denoting a factor of 10⁻¹⁵ — one quadrillionth of the base unit. From the Danish/Norwegian 'femten' (fifteen).

History: Adopted by the CGPM in 1964, one of the first prefixes named after a Scandinavian numeral rather than a Greek or Latin root.

Current use: Used in nuclear and particle physics (femtometers describe the scale of atomic nuclei) and ultrafast laser physics (femtosecond pulses).

Atto (a)

Definition: An SI prefix denoting a factor of 10⁻¹⁸ — one quintillionth of the base unit. From the Danish/Norwegian 'atten' (eighteen).

History: Adopted by the CGPM in 1964 alongside femto-, extending the SI down to the sub-atomic measurement scale.

Current use: Used in high-precision physics measurements, including attosecond-scale laser pulses used to study electron motion within atoms.

Supported Units

Prefix	Symbol	Multiplier (× base)
Yotta	Y	1E+24
Zetta	Z	1E+21
Exa	E	1E+18
Peta	P	1E+15
Tera	T	1E+12
Giga	G	1E+09
Mega	M	1000000
Kilo	k	1000
Hecto	h	100
Deka	da	10
None (base unit)	—	1
Deci	d	0.1
Centi	c	0.01
Milli	m	0.001
Micro	µ	1E-06
Nano	n	1E-09
Pico	p	1E-12
Femto	f	1E-15
Atto	a	1E-18
Zepto	z	1E-21
Yocto	y	1E-24

About These Parameters

Value: The number of "From" prefix units you want to re-express in the "To" prefix. Since prefixes are just multiplier scales, this value can represent anything from a physical quantity's leading digits to a plain abstract number.
From Unit: The SI prefix your value is currently scaled by — for example, the "kilo" in "kilogram" or the "nano" in "nanosecond," entered here without the base unit attached.
To Unit: The SI prefix you want the value re-expressed in. Use the swap button to flip From and To instantly, handy when converting a datasheet figure from one prefix scale to another.

How Prefix Conversion Works

The Formula

Every SI prefix is defined by a fixed power-of-ten multiplier relative to the unprefixed base value. To convert a value from one prefix scale to another:

result = value × (multiplier of "From" prefix ÷ multiplier of "To" prefix)

For Femto → Atto: multiply by 1000. For example, 1 f × 1000 = 1000 a.

A History of Powers of Ten

The original six metric prefixes — kilo, hecto, deka, deci, centi, milli — were adopted by the French Academy of Sciences in 1795 alongside the metric system itself. As science and industry needed to describe ever-larger and ever-smaller quantities, the CGPM (Conférence Générale des Poids et Mesures) extended the table repeatedly: mega and micro in 1960 when the modern SI was formalized, giga and nano the same year, tera and pico following soon after, then peta/femto (1975), exa/atto (1975), and finally zetta/zepto and yotta/yocto in 1991 — the classical range covered on this page. In 2022 the CGPM went further still, adding ronna/ronto and quetta/quecto to keep pace with data-storage and astrophysical quantities that had begun to outgrow even yotta.

Why a Prefix-Only Converter Is Useful

Every other unit converter on this site attaches these same prefixes to one specific base unit — grams, watts, bytes, farads — because that's how the prefix is actually used in practice. But the underlying math of "how much bigger is giga than mega" never changes no matter which unit it's modifying, so it's often faster to reason about the prefix scale on its own: quickly checking that a "giga" figure is a billion and not a million, or converting a "nano" measurement from one datasheet into the "micro" scale used by a different one, without needing to know or care what physical quantity either figure describes.

Example

1 f equals 1000 a. Whatever base unit these prefixes are actually attached to — grams, bytes, watts, seconds — the same multiplier ratio applies: 1 kilo- is always 1,000 times 1 (unprefixed), and 1 mega- is always 1,000 times 1 kilo-, regardless of the quantity being measured.

Frequently Asked Questions

How many Atto are in 1 Femto?

1 Femto (f) equals exactly 1000 Atto (a).

Is giga a billion or a million?

Giga is always a billion (10⁹) times the base unit — a common point of confusion is with "mega," which is a million (10⁶). The two are frequently mixed up in casual conversation about data storage and computing speed, which is exactly the kind of mistake this converter is designed to catch.

Does this converter work for any unit, like grams or bytes?

Yes — this converter deliberately ignores the underlying unit and works purely with the multiplier scale. "1 kilo- to mega-" gives the same ratio (0.001) whether you mentally attach it to grams, watts, bytes, or any other quantity, because the prefix's multiplier is independent of what it's modifying.

What does "None (base unit)" mean in the unit list?

"None (base unit)" represents a value with no prefix attached at all — a plain gram, meter, or watt rather than a kilogram, kilometer, or milliwatt. It's included so you can convert directly between an unprefixed value and any prefixed scale, such as figuring out how many kilo- units equal one plain (unprefixed) unit.

Are ronna, ronto, quetta, and quecto included here?

Not yet — this page covers the classical SI prefix range from yotta (10²⁴) down to yocto (10⁻²⁴), which was complete from 1991 until 2022. The newer 2022 additions (ronna/ronna-, quetta/quecto) sit beyond even yotta and yocto and aren't included in this table.

Convert Femto to Other Prefixes

Possible Prefix Conversions

Yotta to Tera Hecto to Milli Kilo to Giga Femto to Micro Deci to Zetta Yotta to Pico Deka to Yocto Deci to Yotta Exa to Micro Zetta to None (base unit) Yocto to Deci Tera to Giga Femto to Yotta Atto to Mega Mega to Pico Giga to Zetta Pico to Hecto Zetta to Milli Hecto to Deka Milli to Centi Centi to Nano Deci to Femto Hecto to Zepto Atto to Deka Centi to Yotta Nano to Zepto Mega to Zetta Giga to Peta Hecto to Exa Kilo to Nano Atto to Deci Pico to Centi Yocto to Yotta Exa to Deci Zepto to Tera None (base unit) to Peta Atto to Hecto None (base unit) to Atto Mega to Tera Mega to Atto Milli to Pico Tera to Atto Deci to Atto Hecto to None (base unit) Zetta to Mega Tera to Exa Peta to Centi Centi to Exa Atto to Tera Deci to Giga Tera to Yocto Deka to Yotta Yocto to Exa Peta to Femto Kilo to Deci Nano to Yocto Nano to Exa Yotta to Zepto Hecto to Kilo Micro to Peta Deka to Deci Peta to Tera Pico to None (base unit) Femto to Tera Pico to Tera Giga to Milli Zepto to Pico Exa to Femto Micro to Femto Yotta to Hecto Deci to Pico Zetta to Exa Zetta to Nano Deci to Nano Micro to Mega Exa to None (base unit) Deka to None (base unit) Exa to Milli None (base unit) to Giga Hecto to Zetta Micro to Hecto Pico to Zetta Deci to Hecto None (base unit) to Femto Yocto to Deka Exa to Atto Kilo to Yotta Micro to Milli Centi to Pico Yocto to Hecto Zepto to Hecto Milli to Mega Peta to Mega Centi to Zetta Pico to Atto Yotta to Centi Exa to Kilo Yotta to Milli Micro to Deci Micro to Atto Nano to Milli Micro to Kilo Yocto to Atto Hecto to Femto Deci to Deka Milli to Deka Zepto to Nano Deci to Milli Yotta to None (base unit) Yotta to Giga Mega to Micro Peta to Kilo Yotta to Peta Zepto to Yotta Zetta to Micro Micro to Exa Zetta to Deka Micro to Centi Centi to Deka Peta to Yotta Peta to Exa Femto to Giga Nano to Deci Zepto to Deci Femto to Exa Yocto to Centi Hecto to Pico Mega to Hecto Mega to Milli Mega to Centi Nano to None (base unit) Giga to Atto Milli to Yotta Femto to Peta Micro to None (base unit) Tera to Hecto Pico to Nano Kilo to Atto Deka to Pico Zetta to Yotta Yocto to Peta Kilo to Milli Pico to Milli Mega to Deci Deka to Giga Exa to Yocto Kilo to Pico Milli to Deci Atto to None (base unit) Deka to Hecto Centi to Tera Tera to Mega Zetta to Zepto Yocto to None (base unit) Tera to Nano Milli to Peta Zepto to Exa Centi to Hecto Yocto to Femto Zetta to Pico Peta to Yocto Tera to Yotta Exa to Tera Yotta to Nano Deci to Kilo Hecto to Peta Hecto to Centi Nano to Zetta Milli to Tera Atto to Femto Deka to Atto Deka to Exa Zepto to Deka Giga to Exa Kilo to Femto Atto to Peta Deka to Centi Peta to Micro Centi to Atto Mega to None (base unit) Giga to Kilo Pico to Yocto Nano to Mega Centi to Deci Zepto to Giga Atto to Zepto Zetta to Atto None (base unit) to Tera Nano to Deka Zetta to Tera Centi to Mega Yotta to Zetta Yotta to Micro Pico to Zepto Zepto to Peta Deci to None (base unit) Mega to Kilo Micro to Nano Peta to Nano Milli to Exa None (base unit) to Hecto Yocto to Mega Femto to Zepto Yocto to Zetta Exa to Nano Peta to Deci Centi to Milli Atto to Pico Zetta to Yocto Atto to Giga Giga to Micro Nano to Centi Peta to Pico Pico to Peta None (base unit) to Kilo Pico to Mega Giga to Mega Mega to Giga Tera to Zepto Pico to Femto Pico to Yotta Exa to Mega Deka to Zetta Nano to Peta Kilo to Deka Atto to Yocto Milli to Giga Zetta to Femto Femto to Centi Giga to Centi Kilo to Hecto Femto to Zetta Kilo to Exa Hecto to Yocto Kilo to Zepto Deci to Exa Micro to Yotta Kilo to Mega Giga to Femto Deci to Micro Atto to Exa Micro to Tera Tera to Pico Zetta to Giga Hecto to Deci Hecto to Tera Mega to Femto Kilo to Tera Milli to Kilo Atto to Zetta Kilo to Peta Atto to Centi Peta to Zepto Nano to Pico Deci to Mega Yocto to Kilo Exa to Giga Pico to Exa Nano to Atto Peta to Deka Micro to Pico Deka to Micro Mega to Nano Mega to Peta None (base unit) to Exa Exa to Peta None (base unit) to Milli Peta to None (base unit) Exa to Pico Mega to Zepto Hecto to Micro Nano to Hecto Femto to Pico Kilo to Centi Milli to Nano Zetta to Peta Zepto to Zetta Kilo to Zetta Tera to Micro Kilo to Micro Giga to None (base unit) Deka to Femto Yocto to Tera Deka to Nano Nano to Micro Milli to Micro Giga to Deci Yocto to Micro None (base unit) to Nano Giga to Pico Giga to Deka Femto to Deka Yotta to Deka Zepto to Mega Centi to Kilo Exa to Hecto Mega to Yocto None (base unit) to Centi Micro to Deka Femto to Milli Hecto to Mega Micro to Giga Milli to Atto Femto to Yocto Yotta to Mega Zepto to Milli Zetta to Deci Hecto to Nano Deci to Tera Tera to Peta None (base unit) to Pico Tera to Kilo Zepto to Yocto Zepto to Centi Atto to Nano Centi to Zepto Nano to Giga Peta to Milli Zepto to Micro None (base unit) to Deci Milli to Hecto Zetta to Kilo Pico to Micro Femto to Atto Deci to Yocto None (base unit) to Yocto Zepto to Atto Hecto to Giga None (base unit) to Zepto Zetta to Hecto Deka to Mega Tera to Centi Milli to Yocto Nano to Tera Exa to Yotta Tera to Femto Nano to Femto Micro to Zepto Femto to Mega Giga to Nano Mega to Yotta Exa to Zepto Deka to Kilo Yocto to Nano Deka to Milli Giga to Hecto Atto to Micro Tera to Deci Nano to Kilo Zetta to Centi Peta to Hecto Exa to Deka Tera to None (base unit) Yocto to Giga Yotta to Yocto Yocto to Milli Pico to Deka Tera to Zetta Tera to Milli Hecto to Atto Atto to Kilo Yocto to Zepto Centi to Yocto Femto to None (base unit) None (base unit) to Zetta Atto to Milli None (base unit) to Micro Giga to Yotta Zepto to None (base unit) Yocto to Pico Tera to Deka Centi to Peta Yotta to Exa Atto to Yotta Yotta to Atto Giga to Zepto Milli to Femto Giga to Tera Deka to Peta Deci to Peta Mega to Exa Femto to Hecto Deci to Zepto None (base unit) to Mega Giga to Yocto Pico to Kilo Deci to Centi Milli to Zepto Kilo to Yocto Zepto to Kilo Exa to Zetta Peta to Zetta Femto to Nano Centi to Femto Peta to Atto None (base unit) to Yotta Femto to Deci Peta to Giga Zepto to Femto Deka to Zepto Exa to Centi None (base unit) to Deka Yotta to Kilo Micro to Zetta Milli to None (base unit) Nano to Yotta Pico to Deci Mega to Deka Yotta to Deci Kilo to None (base unit) Femto to Kilo Hecto to Yotta Deka to Tera Milli to Zetta Pico to Giga Centi to Giga Micro to Yocto Centi to Micro Yotta to Femto Centi to None (base unit)