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.

Drafted with AI writing toolsUpdated Checked examples: 5

Only used for labels, e.g. m, g, Hz, W
Try
Converted value
MHz
Converted value: 2,400 MHz
Significant figures: 12; Nearest, ties away from zero
Conversion
2.4 GHz = 2,400 MHz
Shift in powers of ten
3

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

Where the two prefixes sit on the powers of ten

GHz10⁹MHz10⁶THz10¹²kHz10³Value × 10³
2.4 GHz with every prefix Rows: 25
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
no prefix10⁰2,400,000,000 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

    es=9,et=6e_s = 9,\quad e_t = 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: mathematical scaling moves the decimal point. The formatted display may still round the result.

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 mathematically; the formatted display may still round. 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.

In the formula, xₛ and xₜ are the source and target values, and eₛ and eₜ are their prefix exponents. A unit without a prefix has exponent zero.

How to convert between metric prefixes

Multiply by 10 to the power of the source exponent minus the target exponent. Giga is 10⁹ and mega is 10⁶, so 2.4 GHz is 2.4 × 10³ = 2,400 MHz. The same rule works for meters, grams, liters, seconds, hertz or watts.

What does milli mean?

Milli (m) means one thousandth, 10⁻³. A millimeter (mm) is 0.001 m, so 1 m is 1,000 mm; likewise a milligram is 0.001 g and a milliliter 0.001 L.

In "mm" the first m is the prefix and the second is the meter. Case matters: Mm, with a capital M, would be a megameter, a million meters.

SI prefix chart

PrefixSymbolFactor
quettaQ10³⁰
ronnaR10²⁷
yottaY10²⁴
zettaZ10²¹
exaE10¹⁸
petaP10¹⁵
teraT10¹²
gigaG10⁹
megaM10⁶
kilok10³
hectoh10²
decada10¹
No prefix—10⁰
decid10⁻¹
centic10⁻²
millim10⁻³
microµ10⁻⁶
nanon10⁻⁹
picop10⁻¹²
femtof10⁻¹⁵
attoa10⁻¹⁸
zeptoz10⁻²¹
yoctoy10⁻²⁴
rontor10⁻²⁷
quectoq10⁻³⁰

The 24 prefixes come from the BIPM SI Brochure. Since CGPM Resolution 3 of 2022 added ronna, quetta, ronto and quecto, they span 60 powers of ten.

Worked prefix conversions

ValueFromToUnit symbolConverted value
2.4gigamegaHz2400
1millinonem0.001
1kilononem1000
5micronanos5000
1quettayottag1000000

Moving to a smaller prefix makes the number bigger: 5 µs is 5,000 ns. Moving to a larger prefix makes it smaller: 1,500 m is 1.5 km.

Prefixes in electronics and optics

  • Capacitors: 100 nF = 0.1 µF = 100,000 pF. Parts are marked in all three, so the same value can look very different.
  • Resistors: 3.3 kΩ is 3,300 Ω.
  • Light: a 450 nm wavelength, in the blue part of the spectrum, is 0.45 µm.

Squared and cubed units

A prefix on a squared unit is squared too. 1 m is 1,000 mm, but 1 m² is 1,000,000 mm² and 1 m³ is 1,000,000,000 mm³.

Shifting 2.5 m² by 10³ gives 2,500 mm², a thousand times too small; the answer is 2,500,000 mm². For areas and volumes use the area converter or volume converter, and remember that 1 cm³ is exactly 1 mL.

What to enter

  • The number alone: type 2.4 and pick giga; the letters GHz are not part of the number.
  • None for the plain unit: it stands for exponent 0, such as m or g with no prefix.
  • The unit symbol is a label: it never changes the arithmetic, so m² is not squared for you.

Common mistakes

  • Mixing up m and M. 100 mHz is a tenth of a hertz, while 100 MHz sits in the FM radio band.
  • Using 1,024 for kilo. In the SI, kilo is exactly 1,000. Binary multiples such as the kibibyte (1,024 bytes) have their own names; the data storage converter keeps them apart.
  • Shifting a temperature. Celsius to Fahrenheit needs an offset as well as a scale, so use the temperature converter.

The scientific notation calculator does arithmetic with powers of ten, the length converter turns metric lengths into inches and feet, and the lakh and crore converter names large numbers in words.

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.

About this calculator

xt=xs×10es−etx_t = x_s \times 10^{e_s-e_t}

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

This calculator includes 5 worked examples with independently sourced answers. They run in the test suite, and you can run them here too.

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