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SI and metric prefix converter

Convert between SI metric prefixes such as giga, mega, kilo, milli, micro and nano, from quecto (10⁻³⁰) to quetta (10³⁰), including the 2022 additions.

更新日 検証済みの例：5

Only used for labels, e.g. m, g, Hz, W
試す
変換後の値
MHz
変換後の値: 2,400 MHz
有効桁数：12；最も近い値へ、等距離ならゼロから遠い値へ
単位換算
2.4 GHz = 2,400 MHz
Shift in powers of ten
3

Going from giga (10⁹) to mega (10⁶) moves the decimal point 3 places to the right: 2.4 GHz = 2,400 MHz.

Where the two prefixes sit on the powers of ten

THz10¹²GHz10⁹MHz10⁶kHz10³hHz10²daHz10¹value × 10³
2.4 GHz with every prefix 行数：25
PrefixFactor値
quetta (Q)10³⁰2.4 × 10⁻²¹ QHz
ronna (R)10²⁷2.4 × 10⁻¹⁸ RHz
yotta (Y)10²⁴2.4 × 10⁻¹⁵ YHz
zetta (Z)10²¹2.4 × 10⁻¹² ZHz
exa (E)10¹⁸2.4 × 10⁻⁹ EHz
peta (P)10¹⁵0.0000024 PHz
tera (T)10¹²0.0024 THz
giga (G)10⁹2.4 GHz
mega (M)10⁶2,400 MHz
kilo (k)10³2,400,000 kHz
hecto (h)10²24,000,000 hHz
deca (da)10¹240,000,000 daHz
none10⁰2,400,000,000 Hz
deci (d)10⁻¹24,000,000,000 dHz
centi (c)10⁻²240,000,000,000 cHz
milli (m)10⁻³2,400,000,000,000 mHz
micro (µ)10⁻⁶2.4 × 10¹⁵ µHz
nano (n)10⁻⁹2.4 × 10¹⁸ nHz
pico (p)10⁻¹²2.4 × 10²¹ pHz
femto (f)10⁻¹⁵2.4 × 10²⁴ fHz
atto (a)10⁻¹⁸2.4 × 10²⁷ aHz
zepto (z)10⁻²¹2.4 × 10³⁰ zHz
yocto (y)10⁻²⁴2.4 × 10³³ yHz
ronto (r)10⁻²⁷2.4 × 10³⁶ rHz
quecto (q)10⁻³⁰2.4 × 10³⁹ qHz
計算方法 S

  1. Prefix powers

    giga=109,mega=106\text{giga} = 10^{9},\quad \text{mega} = 10^{6}

    SI Brochure Table 7; ronna, quetta, ronto and quecto since 2022.

  2. Shift the power of ten

    2.4×109−6=2.4×103=2,400 MHz2.4 \times 10^{9 - 6} = 2.4 \times 10^{3} = 2{,}400\ \text{MHz}

    Powers of ten are exact, so the result has the same digits as the value you entered.

SI and metric prefix converterについて

An SI prefix multiplies a unit by a power of ten: kilo is 10³, mega 10⁶, milli 10⁻³ and nano 10⁻⁹. Converting between two prefixes multiplies the value by 10 raised to the difference of their exponents, which moves the decimal point without changing any digits. The converter covers all 24 SI prefixes, from quecto (10⁻³⁰) to quetta (10³⁰).

Engineers and students use it to move between scales of one unit. The default turns the 2.4 GHz Wi-Fi band into 2,400 MHz, a shift of three powers of ten. The unit symbol field only labels the result, so the same conversion works for metres, grams, hertz or watts.

Two BIPM rules apply to every prefix: prefixes are never combined (write nm, not mµm), and because the kilogram already carries one, prefixes attach to the gram: 1 mg, not 1 µkg.

計算例

2.4 GHz in MHz

値
2.4
変換元
giga (G, 10⁹)
変換先
mega (M, 10⁶)
Unit symbol
Hz
変換後の値
2,400 MHz
単位換算
2.4 GHz = 2,400 MHz
Shift in powers of ten
3

照合元：giga = 10⁹, mega = 10⁶ (SI Brochure Table 7): 2.4 × 10³

1 km in m

値
1
変換元
kilo (k, 10³)
変換先
none (10⁰)
Unit symbol
m
変換後の値
1,000 m

照合元：kilo = 10³

1 quetta in yotta (2022 prefix)

値
1
変換元
quetta (Q, 10³⁰)
変換先
yotta (Y, 10²⁴)
Unit symbol
g
変換後の値
1,000,000 Yg
Shift in powers of ten
6

照合元：quetta = 10³⁰ (CGPM 2022), yotta = 10²⁴

Smallest to largest: quecto to quetta

値
1
変換元
quecto (q, 10⁻³⁰)
変換先
quetta (Q, 10³⁰)
Unit symbol
g
Shift in powers of ten
-60
変換後の値
1 × 10⁻⁶⁰ Qg

照合元：10⁻³⁰ / 10³⁰ = 10⁻⁶⁰

よくある質問

What are the SI prefixes in order?

There are 24. From largest: quetta (Q, 10³⁰), ronna (R, 10²⁷), yotta (Y, 10²⁴), zetta (Z), exa (E), peta (P), tera (T), giga (G), mega (M), kilo (k, 10³), hecto (h, 10²) and deca (da, 10¹). Then the submultiples: deci (d), centi (c), milli (m, 10⁻³), micro (µ), nano (n), pico (p), femto (f), atto (a), zepto (z), yocto (y), ronto (r) and quecto (q, 10⁻³⁰).

What are the newest SI prefixes?

Ronna (R, 10²⁷), quetta (Q, 10³⁰), ronto (r, 10⁻²⁷) and quecto (q, 10⁻³⁰), adopted by the 27th General Conference on Weights and Measures (CGPM) in November 2022. They were the first additions since zetta, yotta, zepto and yocto in 1991. On the new scale the Earth's mass, about 5.97 × 10²⁴ kg, is roughly 6 ronnagrams.

How do I convert between metric prefixes?

Subtract the exponents and move the decimal point that many places. From giga (10⁹) to mega (10⁶) is 9 − 6 = 3 places to the right, so 2.4 GHz = 2,400 MHz; from micro (10⁻⁶) to nano (10⁻⁹) is also 3 places, so 5 µs = 5,000 ns. Moving to a larger prefix shifts the point left: 1,500 m = 1.5 km.

Why is kilo a lowercase k but mega an uppercase M?

The SI writes the symbols for multiples from mega (M, 10⁶) upward in capitals, while kilo (k), hecto (h), deca (da) and every submultiple are lowercase. The case changes the value: 1 MW (megawatt) is 10⁹ times 1 mW (milliwatt). Writing K for kilo is wrong in the SI, because K is the symbol for the kelvin.

Does kilo mean 1,000 or 1,024 in computing?

In the SI, kilo always means exactly 1,000, so 1 kbit = 1,000 bits and 1 GB = 10⁹ bytes (NIST). For powers of two the IEC approved binary prefixes in December 1998: 1 KiB (kibibyte) = 1,024 bytes and 1 GiB = 2³⁰ = 1,073,741,824 bytes. The gap grows with size, which is why a 1 TB drive shows about 931 GiB.

「SI and metric prefix converter」の精度はどのくらいですか？

精度は入力値と計算方法の前提に依存します。十進演算には有効数字50桁を使いますが、推定、数値計算手法、元データの精度はそれより低い場合があります。表示の丸め処理でこれらの制約がなくなるわけではありません。 独立した出典の解答と照合した計算例：5。 例えば、「2.4 GHz in MHz」はgiga = 10⁹, mega = 10⁶ (SI Brochure Table 7): 2.4 × 10³と照合しています。

この計算方法の出典は何ですか？

BIPM — The International System of Units (SI Brochure, 9th ed.), Table 7: SI prefixes; BIPM — CGPM 2022 Resolution 3: ronna, quetta, ronto, quecto.

この計算機について

xto=xfrom×10 efrom−etox_{\text{to}} = x_{\text{from}} \times 10^{\,e_{\text{from}} - e_{\text{to}}}

出典

  1. BIPM — The International System of Units (SI Brochure, 9th ed.), Table 7: SI prefixes
  2. BIPM — CGPM 2022 Resolution 3: ronna, quetta, ronto, quecto

出典と照合済み

この計算機には、独立した出典の解答を使った計算例が 5 件あります。テストに組み込まれており、ここでも実行できます。

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