Scientific Notation Converter

Convert numbers to scientific notation and back: 0.000045 = 4.5 × 10⁻⁵. Exact decimal form, E notation, engineering notation with SI prefixes and significant figures.

Number — standard (0.000045), E notation (4.5e-5) or 4.5 x 10^-5

Round to significant figures

Scientific notation

4.5 × 10⁻⁵

E notation

4.5e-5

Engineering notation

45 × 10⁻⁶= 45 µ (micro)

Standard (decimal) form

0.000045

Significant figures as typed: 2. Write in calculators and spreadsheets as 4.5E-5.

Powers of ten and SI prefixes

Powers of ten, decimal form and SI prefixes
Power	Decimal	Prefix	Symbol
10¹²	1,000,000,000,000	tera	T
10⁹	1,000,000,000	giga	G
10⁶	1,000,000	mega	M
10³	1,000	kilo	k
10⁰	1	—	—
10⁻³	0.001	milli	m
10⁻⁶	0.000001	micro	µ
10⁻⁹	0.000000001	nano	n
10⁻¹²	0.000000000001	pico	p

How scientific notation works

A number in scientific notation is a coefficient from 1 up to (but not including) 10, times 10 raised to a whole-number power. Move the decimal point until one non-zero digit is left of it; the number of places moved is the exponent — positive if you moved left (big numbers), negative if you moved right (small numbers). 123,000 → 1.23 × 10⁵; 0.000045 → 4.5 × 10⁻⁵.

This converter does the arithmetic on the digits themselves rather than in floating point, so long values such as 602214076000000000000000 or 0.00000000015 come back exactly, with no stray 0.0000000001 errors.

E notation, engineering notation and SI prefixes

Calculators and spreadsheets write × 10ⁿ as "e": 6.02e+23 means 6.02 × 10²³. Engineering notation keeps the exponent a multiple of 3 so it lines up with SI prefixes — 0.000047 F is 47 × 10⁻⁶ F, or 47 µF. The prefix names and symbols (kilo k 10³, mega M 10⁶, micro µ 10⁻⁶, nano n 10⁻⁹ and so on, up to quetta Q 10³⁰) follow NIST Special Publication 811, Table 5.

Frequently asked questions

How do I write 0.0005 in scientific notation?

5 × 10⁻⁴. The decimal point moves 4 places to the right to reach 5, so the exponent is −4.

What is 3.2 × 10^6 in standard form?

3,200,000. A positive exponent moves the decimal point that many places to the right.

What does 1e-6 mean?

It is E notation for 1 × 10⁻⁶, which is 0.000001 — one millionth, the SI prefix micro (µ).

How many significant figures does 0.00450 have?

Three: 4, 5 and the trailing 0 (it is after the decimal point, so it was measured). Leading zeros never count. In scientific notation it is 4.50 × 10⁻³.

What is the difference between scientific and engineering notation?

Scientific notation has one digit before the point (4.7 × 10⁻⁵). Engineering notation uses exponents that are multiples of 3 (47 × 10⁻⁶) so the value reads straight off as an SI prefix (47 µ).