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About this tool
Convert large or tiny numbers into scientific and engineering notation.
This scientific notation calculator rewrites any number as a × 10^n, where the coefficient a satisfies 1 ≤ |a| < 10 and n is a whole number, and also gives the engineering form in which n is forced to a multiple of 3 so it lines up with an SI prefix such as kilo (10^3) or micro (10^-6). It applies the standard significant-figure rules to arithmetic: multiplication and division keep the fewest significant figures of the operands, addition and subtraction round to the coarsest decimal place. It is built for physics, chemistry and engineering students and for anyone reading data sheets full of very large or very small numbers.
Open Scientific Notation Calculator on AltFTool — it loads instantly in your browser.
Choose a Mode - "Convert one number" or "Calculate with two numbers" - and type the value as 0.000123, 1.23e-4 or 1.23 x 10^-4.
Set "Significant figures to display (1-17)", and in calculate mode pick Add (a + b), Subtract (a - b), Multiply (a x b) or Divide (a / b).
Read the Scientific notation, Engineering notation, SI prefix and Expanded decimal rows, then press Copy result.
Every value is shown in scientific form and in engineering form with its SI prefix.
The tool states which rule it applied and why the result has that many digits.
Accepts 0.000123, 1.23e-4 and 1.23 × 10^-4 interchangeably.
Move the decimal point until exactly one non-zero digit sits to its left, then multiply by 10 raised to the number of places you moved. Moving left gives a positive exponent and moving right a negative one, so 299792458 becomes 2.998 × 10^8 and 0.000123 becomes 1.23 × 10^-4.
Scientific notation keeps the coefficient between 1 and 10 with any integer exponent; engineering notation restricts the exponent to multiples of 3, so the coefficient runs from 1 up to 1000. Engineering form exists because every multiple-of-3 exponent has an SI prefix — 47.2 × 10^-6 F reads directly as 47.2 µF.
For multiplication and division, the answer takes the smallest significant-figure count of the inputs: 2.5 × 10^3 (2 sig figs) times 4.00 (3 sig figs) gives 1.0 × 10^4. For addition and subtraction, round to the coarsest last decimal place instead: 12.34 + 1.2 = 13.5, because 1.2 is only known to the tenths place.
About 1.798 × 10^308, and the smallest is roughly 5 × 10^-324, because calculations run in IEEE-754 double precision with around 17 significant decimal digits. Beyond those limits the tool returns an overflow message instead of a misleading rounded answer.
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