Enter a number in any form (0.00047, 4.7e-4, 4.7 × 10^-4 or 47k) to get it in engineering notation, where the power of ten is always a multiple of 3, together with the matching SI prefix, scientific notation and plain decimal form.
Last updated:
Decimal, 4.7e-4, 4.7 × 10^-4, or with an SI prefix like 47k, 3.3M, 220n
e.g. F, Ω, Hz, m, W, V
Enter your values to see the result.
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How to use the Engineering Notation Converter
Type the number in any common format: 0.00047, 4.7e-4, 4.7 × 10^-4 or 470µ.
Choose the precision: keep the digits as entered or round to a set number of significant figures.
Add a unit if you like (F, Ω, Hz…) so the prefixed result reads like 470 µF.
Press Convert and read the engineering notation, SI prefix form, scientific notation and standard form.
Compare prefixes in the table, then copy the results.
How engineering notation works
Engineering notation is a version of scientific notation in which the exponent of ten must be a multiple of 3. The number in front, the mantissa, is then always between 1 and 1,000. The rule is simple:
Find the scientific notation exponent n (the number of places the decimal point moves to leave one digit in front).
Round it down to a multiple of 3: e = 3 × floor(n ÷ 3).
Divide the number by 10e to get the mantissa.
Example: 0.000 047 = 4.7 × 10⁻⁵. floor(−5 ÷ 3) = −2, so e = −6 and the mantissa is 4.7 × 10¹ = 47. Answer: 47 × 10⁻⁶, or 47 µ (47 µF for a capacitor).
Watch negative exponents: "round down" means toward minus infinity, so −4 becomes −6, not −3. That keeps the mantissa at 1 or more.
SI prefixes for engineering notation
Power
Prefix
Symbol
Example
10¹²
tera
T
2 TB drive
10⁹
giga
G
2.4 GHz Wi-Fi
10⁶
mega
M
12.5 MHz clock
10³
kilo
k
4.7 kΩ resistor
10⁰
(none)
230 V
10⁻³
milli
m
20 mA
10⁻⁶
micro
µ
470 µF capacitor
10⁻⁹
nano
n
22 nF capacitor, 650 nm light
10⁻¹²
pico
p
100 pF capacitor
10⁻¹⁵
femto
f
femtosecond laser pulse
Also recognized: peta (P, 10¹⁵), exa (E, 10¹⁸), zetta (Z), yotta (Y), ronna (R, 10²⁷), quetta (Q, 10³⁰), and atto (a, 10⁻¹⁸), zepto (z), yocto (y), ronto (r), quecto (q, 10⁻³⁰). Prefixes for 10², 10¹, 10⁻¹ and 10⁻² (hecto, deca, deci, centi) exist but are not used in engineering notation.
Tips
Capital M vs small m: M is mega (a million), m is milli (a thousandth). Typing 3M and 3m gives values a billion times apart.
Typing µ: if your keyboard has no µ, type u (4.7u = 4.7 × 10⁻⁶), the usual workaround in electronics.
Significant figures: 470 × 10⁻⁶ is ambiguous about whether the zero is significant. Choose a precision to force it, for example 470.0 × 10⁻⁶ for four figures.
Calculator ENG mode: most scientific calculators have an ENG display mode that shows results exactly like the main result above.
Frequently asked questions
What is engineering notation?
Engineering notation writes a number as a mantissa from 1 to less than 1,000 multiplied by a power of ten whose exponent is a multiple of 3, such as 47 × 10³ or 470 × 10⁻⁶. Each of those powers matches an SI prefix (kilo, mega, milli, micro and so on).
How is engineering notation different from scientific notation?
Scientific notation keeps one non-zero digit before the decimal point and allows any exponent (4.7 × 10⁻⁴). Engineering notation restricts the exponent to multiples of 3, so the mantissa can be 1 to 999.999… (470 × 10⁻⁶). Both represent the same value.
How do you convert a number to engineering notation?
Write it in scientific notation to find the exponent, round that exponent down to the nearest multiple of 3, then move the decimal point the same number of places. For 0.00047: 4.7 × 10⁻⁴ → exponent −6 → 470 × 10⁻⁶.
What SI prefix goes with each exponent?
10³ kilo (k), 10⁶ mega (M), 10⁹ giga (G), 10¹² tera (T); 10⁻³ milli (m), 10⁻⁶ micro (µ), 10⁻⁹ nano (n), 10⁻¹² pico (p). The full set runs from quecto (10⁻³⁰) to quetta (10³⁰), the newest prefixes adopted in 2022.
Why do engineers use engineering notation?
Because the exponents line up with SI prefixes, numbers translate directly into readable units: 4.7 × 10³ Ω is 4.7 kΩ and 22 × 10⁻⁹ F is 22 nF. Component values, frequencies and data sizes are usually written this way.
How do I write 12,500,000 in engineering notation?
12,500,000 = 1.25 × 10⁷ in scientific notation. Rounding the exponent down to 6 gives 12.5 × 10⁶, which is 12.5 M (for example 12.5 MHz).
What does E-notation like 470E-6 mean?
E stands for "times ten to the power of". 470E-6 is 470 × 10⁻⁶ = 0.00047. Calculators and spreadsheets use this format when they cannot show superscripts.
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