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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.

Updated Checked against 5 worked examples

Only used for labels, e.g. m, g, Hz, W
Try
Converted value
MHz
Converted value: 2,400 MHz
Shown to 12 significant figures, half-up
Conversion
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 (25 rows)
PrefixFactorValue
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
How it's calculated 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.

About the SI and metric prefix converter

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.

Worked examples

2.4 GHz in MHz

Value
2.4
From
giga (G, 10⁹)
To
mega (M, 10⁶)
Unit symbol
Hz
Converted value
2,400 MHz
Conversion
2.4 GHz = 2,400 MHz
Shift in powers of ten
3

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

1 km in m

Value
1
From
kilo (k, 10³)
To
none (10⁰)
Unit symbol
m
Converted value
1,000 m

Checked against: kilo = 10³

1 quetta in yotta (2022 prefix)

Value
1
From
quetta (Q, 10³⁰)
To
yotta (Y, 10²⁴)
Unit symbol
g
Converted value
1,000,000 Yg
Shift in powers of ten
6

Checked against: quetta = 10³⁰ (CGPM 2022), yotta = 10²⁴

Smallest to largest: quecto to quetta

Value
1
From
quecto (q, 10⁻³⁰)
To
quetta (Q, 10³⁰)
Unit symbol
g
Shift in powers of ten
-60
Converted value
1 × 10⁻⁶⁰ Qg

Checked against: 10⁻³⁰ / 10³⁰ = 10⁻⁶⁰

Questions

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.

How accurate is the SI and metric prefix converter?

Accuracy depends on your inputs and the method's assumptions. Decimal arithmetic uses 50 significant digits, but estimates, numerical methods and source data can be less precise; the displayed rounding does not remove those limits. It is checked against 5 worked examples whose answers come from independent sources; for example, “2.4 GHz in MHz” is checked against giga = 10⁹, mega = 10⁶ (SI Brochure Table 7): 2.4 × 10³.

Where does the method come from?

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

About this calculator

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

Sources

  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

Checked against references

5 worked examples with independently sourced answers ship with this calculator. They run in the test suite; you can run them here too.

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