About the Engineering Notation Converter
This engineering notation converter rewrites a number so that the exponent of ten is always a multiple of three and the mantissa sits between 1 and 999. 0.0000047 becomes 4.7 × 10⁻⁶, which reads directly as 4.7 μ (micro), and 123,456,789 becomes 123.456789 × 10⁶, or 123.456789 M (mega). Add a unit such as F, Hz, Ω or W and the SI-prefixed form is ready to write on a schematic or a lab report.
Engineers, electronics hobbyists and physics students use engineering notation because each step of 10³ matches an SI prefix, so values line up with component markings and meter readings. The tool also shows ordinary scientific notation, E-notation as used by calculators and spreadsheets, and the full decimal form.
You can type plain decimals, E-notation (4.7e-6), “× 10^” forms or values that already carry a prefix letter such as 4.7k or 220n. Choose a number of significant figures to round the mantissa, or leave it at 0 to keep every digit you typed. Prefixes from quecto (10⁻³⁰) to quetta (10³⁰) are supported.
How to use the engineering notation converter
- 1Type the number in any common format (decimal, 4.7e-6, 4.7 × 10^-6 or 4.7k).
- 2Optionally choose how many significant figures to keep.
- 3Add a unit such as F, Hz or Ω to get a ready-to-use SI value.
- 4Read the engineering notation, SI-prefixed form and the scientific and E-notation equivalents.
Formula and method
Start from scientific notation x = d.ddd × 10ᵉ. Round e down to the nearest multiple of 3 to get the engineering exponent 3k = 3·⌊e/3⌋, then shift the decimal point right by e − 3k places (0, 1 or 2) so the mantissa lies between 1 and 999.999…. For 4.7 × 10⁻⁶ the exponent is already a multiple of 3; for 1.23456789 × 10⁸ it becomes 123.456789 × 10⁶.
Each multiple of 3 corresponds to an SI prefix: 10³ kilo (k), 10⁶ mega (M), 10⁹ giga (G), 10⁻³ milli (m), 10⁻⁶ micro (μ), 10⁻⁹ nano (n), 10⁻¹² pico (p) and so on, as defined by the BIPM. The conversion is done on the decimal digits as text, so no floating-point rounding is introduced.
- m
- Mantissa, 1 ≤ |m| < 1000
- 3k
- Exponent, always a multiple of 3
- e
- Exponent in ordinary scientific notation
Worked examples
A 0.0000047 F capacitor
0.0000047 = 4.7 × 10⁻⁶. The exponent −6 is already a multiple of 3, and 10⁻⁶ is the micro prefix, so the capacitor is 4.7 μF.
123,456,789 Hz
In scientific notation this is 1.23456789 × 10⁸. Rounding the exponent 8 down to 6 moves the decimal point two places right, giving 123.456789 × 10⁶ = 123.456789 MHz.
Rounding 0.00000000025137 s to 3 significant figures
The value is 2.5137 × 10⁻¹⁰; to 3 significant figures that is 2.51 × 10⁻¹⁰. The nearest lower multiple of 3 is −12, so shift two places: 251 × 10⁻¹² seconds, or 251 picoseconds.
A negative value: −45,000 W
−45,000 = −4.5 × 10⁴. Dropping the exponent to 3 gives −45 × 10³, which is −45 kW.
Frequently asked questions
What is engineering notation?+
It is a form of scientific notation in which the power of ten is always a multiple of three (…, 10⁻⁶, 10⁻³, 10⁰, 10³, 10⁶, …) and the number in front is between 1 and 999. Each power then matches an SI prefix such as milli, kilo or mega.
How is engineering notation different from scientific notation?+
Scientific notation keeps exactly one non-zero digit before the decimal point (4.7 × 10⁴), while engineering notation allows one to three digits so the exponent is a multiple of 3 (47 × 10³). Scientific notation is standard in science; engineering notation maps directly to units like kΩ or MHz.
How do I convert scientific notation to engineering notation?+
Lower the exponent to the nearest multiple of 3 below it and move the decimal point right by the same number of places. For 3.3 × 10⁵: the nearest multiple of 3 is 3, a difference of 2, so it becomes 330 × 10³ (330 k).
What do the SI prefixes stand for?+
The common ones are pico (p, 10⁻¹²), nano (n, 10⁻⁹), micro (μ, 10⁻⁶), milli (m, 10⁻³), kilo (k, 10³), mega (M, 10⁶), giga (G, 10⁹) and tera (T, 10¹²). In 2022 the range was extended with ronna, quetta, ronto and quecto (10²⁷, 10³⁰, 10⁻²⁷, 10⁻³⁰).
How do I set engineering notation on a calculator?+
Most scientific calculators have an ENG mode (often under MODE or SETUP), and Excel offers the custom number format ##0.0E+0. In ENG mode the display shows the mantissa and an exponent that is always a multiple of 3, just like this converter.
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