Scientific Notation Calculator

Convert any number to scientific notation, E-notation and engineering notation — or add, subtract, multiply and divide numbers already written in scientific notation.

Scientific notation —
E-notation —
Engineering notation —
Decimal —

How to Convert to Scientific Notation

One rule: one non-zero digit before the decimal point.

1

Type any number

Plain decimals like 123400 or 0.00042 and e-notation like 3.4e5 both work, commas included. The conversion happens as you type, on the exact digits you entered. Want it spelled out in English instead? Use the Numbers to Words Converter.

2

Read all four forms

Scientific notation (a × 10n, also called standard form), E-notation for spreadsheets and code, engineering notation with exponents in steps of 3 to match metric prefixes, and the full decimal. The explanation shows how far the decimal point moved.

3

Or do the math in notation

Switch to the math tab to add, subtract, multiply or divide two numbers in scientific notation — the answer comes back normalized, with the exponent rule it used. New to the rules? The guides walk through each operation step by step: multiplying, dividing, and adding & subtracting. Converting measurements too? The Unit Converter and the unit conversion chart pair well with engineering notation.

Frequently Asked Questions

How do you write a number in scientific notation?
Move the decimal point until exactly one non-zero digit is left of it, and count how many places you moved. That count is the exponent of 10: positive if you moved the point left (a large number), negative if you moved it right (a small number). For example, 123,400 becomes 1.234 × 105 because the point moves five places left, and 0.00042 becomes 4.2 × 10−4 because it moves four places right. In the UK the same form is called standard form. The convert mode does this instantly and explains how many places the point moved, so you can check your own working.
What are E-notation and engineering notation?
E-notation is the compact form calculators, spreadsheets and programming languages use: the mantissa, the letter e, then the exponent, so 4.2 × 10−4 is written 4.2e-4. It means exactly the same thing. Engineering notation is a variant of scientific notation where the exponent is always a multiple of 3, so it lines up with unit prefixes like kilo (103), mega (106), milli (10−3) and micro (10−6) — 0.00042 becomes 420 × 10−6, which reads directly as 420 micro-units. This converter shows all three forms side by side, plus the full decimal expansion when it is short enough to print.
How do you add, subtract, multiply or divide in scientific notation?
To multiply, multiply the mantissas and add the exponents: (3 × 108) × (2 × 10−5) is 6 × 103. To divide, divide the mantissas and subtract the exponents. To add or subtract, first rewrite both numbers with the same exponent, then add or subtract the mantissas and re-normalize so one digit is left of the point. The math mode accepts both plain decimals and e-notation like 3e8, applies the right rule, and returns the answer already normalized — with a reminder of which rule it used.
Is the scientific notation calculator free, and how precise is it?
It is completely free, with no account or sign-up, and everything runs in your browser — nothing you type is uploaded or stored, and the tool keeps working offline once loaded. Conversions are done on the digits of the number you typed rather than on a rounded float, so converting between decimal, scientific, E- and engineering notation is exact for any length of number. Arithmetic in math mode uses your browser's double-precision floats, which are accurate to about 15–17 significant digits and cover magnitudes up to about 1.8 × 10308.