Scientific Notation Converter
Any number to scientific notation, engineering notation with SI prefix, e-notation and the expanded decimal — exact, optionally rounded to significant figures.
Significand and exponent, the scientific, engineering (with SI prefix) and e-notation forms, the expanded decimal, the significant figures of the input and output and the order of magnitude.
Example: 0.000123 is 1.23 × 10⁻⁴, engineering 123 × 10⁻⁶ (123 µ); 602 214 076 000 000 000 000 000 is 6.02214076 × 10²³ and, to three figures, 6.02 × 10²³; 999.9 to two figures rounds up to 1.0 × 10³.
Read as text,
written every way.
How the number is read, what each notation is, and how significant figures are counted.
Reading
The input is parsed as exact decimal text — digits, a point, an exponent in any of the common spellings (e23, E+23, × 10^23, ×10²³) or an SI prefix letter (12.5k, 3.3µ) — so nothing is converted to a floating-point value and 0.1 stays 0.1. The significand is the digit string with leading zeros removed; the exponent is where the decimal point sits.
The notations
Scientific: one non-zero digit before the point, d.ddd × 10ⁿ. Engineering: the exponent a multiple of three so the SI prefix applies directly (123 × 10⁻⁶ = 123 µ). E-notation is the same as scientific in the form programs read. The expanded form writes the value out in full.
Significant figures
Trailing zeros count when a decimal point was written (1.50 has three) and not in a bare integer (1500 has two); rounding to a chosen number of figures is half-up on the decimal digits, with carry (999.9 → 1.0 × 10³). Nothing leaves the browser; the same four anonymous usage counts as the rest of the site apply.
SOURCES
- Number read as exact decimal text; scientific form d.ddd × 10ⁿ with one non-zero digit before the point; engineering form with n a multiple of three; SI prefixes from the BIPM SI Brochure
Last reviewed 21 September 2026. How results are checked: How we verify.