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Convert None (base unit) to Zepto

None (base unit) (—) to Zepto (z) 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.

The numeric value you want to convert. Decimals are accepted.

Result

1 — = 1E+21 z

1 None (base unit) = 1E+21 Zepto

1 Zepto = 1E-21 None (base unit)

1 — in every supported prefix

Conversion chart: None (base unit) to Zepto

Conversion table

None (base unit) (—) Zepto (z)
0.01 — 1E+19 z
0.1 — 1E+20 z
1 — 1E+21 z
2 — 2E+21 z
3 — 3E+21 z
5 — 5E+21 z
10 — 1E+22 z
20 — 2E+22 z
50 — 5E+22 z
100 — 1E+23 z
1000 — 1E+24 z

None (base unit) (—)

Definition: The unprefixed base value — a multiplier of exactly 1, representing a quantity with no SI prefix attached at all (e.g. a plain gram, meter, or watt rather than a kilogram, kilometer, or milliwatt).

History: This isn't a historical unit in its own right — it's simply the reference point the entire SI prefix ladder is built around, against which every prefix above and below is defined as a power of ten.

Current use: Used as the baseline whenever a quantity is expressed without any prefix, and as the anchor point for converting any other prefix on this page to any other.

Zepto (z)

Definition: An SI prefix denoting a factor of 10⁻²¹ — one sextillionth of the base unit.

History: Adopted by the CGPM in 1991 alongside zetta-, extending the small end of the SI prefix table to mirror the newly added large-scale prefixes.

Current use: Rarely used outside theoretical physics and chemistry contexts involving individual-molecule mass calculations.

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 None (base unit) → Zepto: multiply by 1E+21. For example, 1 — × 1E+21 = 1E+21 z.

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 — equals 1E+21 z. 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 Zepto are in 1 None (base unit)?

1 None (base unit) (—) equals exactly 1E+21 Zepto (z).

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 None (base unit) to Other Prefixes

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

Possible Prefix Conversions

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

See also