Scientific Notation Converter

Convert ordinary numbers to scientific notation (mantissa × 10^n) and back.

Why use this tool?

Turn very large or very small numbers into scientific notation (like 6.371 × 10⁶) and back, as used in science, engineering and calculators.

How to use it

  1. Choose the direction: decimal to scientific, or scientific to decimal.
  2. Enter the number (or the mantissa and exponent).
  3. Read the converted form.

How scientific notation works

Scientific notation writes a number as a value between 1 and 10 (the mantissa or coefficient) multiplied by a power of ten. The exponent says how many places the decimal point moves: positive for large numbers, negative for small ones.

Large number: Earth's mean radius, 6,371,000 meters, becomes 6.371 × 10⁶, because the decimal point moves six places to the left. Small number: 0.00042 becomes 4.2 × 10⁻⁴, because the point moves four places to the right.

E notation on calculators and in code

Calculators, spreadsheets and programming languages write the same thing with the letter E: 6.371E6 means 6.371 × 10⁶, and 4.2E-4 means 4.2 × 10⁻⁴. Excel switches to this format automatically for numbers too wide for a cell, which is why long ID numbers sometimes turn into something like 1.23457E+11. Formatting the cell as Text or Number shows the full value.

Calculating with powers of ten

Multiplying: multiply the coefficients and add the exponents. (3 × 10⁴) × (2 × 10³) = 6 × 10⁷. Dividing: divide the coefficients and subtract the exponents. (8 × 10⁹) ÷ (2 × 10³) = 4 × 10⁶.

If the coefficient ends up outside 1-10, adjust it: 25 × 10⁵ becomes 2.5 × 10⁶. Adding and subtracting need the same exponent first: 3 × 10⁴ + 5 × 10³ = 3 × 10⁴ + 0.5 × 10⁴ = 3.5 × 10⁴.

Significant figures

The digits in the coefficient show how precise a value is. 6.371 × 10⁶ has four significant figures and claims precision to the nearest thousand meters, while 6.4 × 10⁶ claims only the nearest hundred thousand. When converting, keep the number of significant figures your original measurement justifies rather than adding false precision.

Frequently asked questions

What does 1.5E+8 mean?

1.5 × 10⁸, or 150,000,000. The number after E is the power of ten.

How do I write 0.000075 in scientific notation?

Move the decimal point five places right to get 7.5, so it's 7.5 × 10⁻⁵.

Why does Excel show my long number as 1.23E+11?

The number is too wide for the cell's current format. Widen the column or format it as Number or Text to see every digit.