Decimal to Percent Calculator
Convert a decimal to a percentage or a percentage to a decimal. Both boxes work independently, and neither introduces a rounding error.
Convert either direction
7.5% as a decimal
0.075
Decimal as a fraction
3/40
Decimal as a percentage
7.5%
0.075 × 100
Both directions in one line
- Decimal to percentage — multiply by 100, which moves the point two places right.
- Percentage to decimal — divide by 100, which moves it two places left.
Worked examples
0.075 → 7.5% (point moves right two places)
0.29 → 29%
1.5 → 150%
7.5% → 0.075 (point moves left two places)
Why two places
"Per cent" means per hundred, and 100 is ten squared. Every factor of ten moves the decimal point one place, so a factor of a hundred moves it two. There is nothing to memorise beyond that.
The mistake that costs money
0.5 and 0.5% are not the same number. 0.5 is 50%, while 0.5% is 0.005 — a hundred times smaller.
This bites hardest in spreadsheets. Typing 0.05 into a cell formatted as a percentage may display "5%" while another cell holds a literal 5, and the two will not agree in any formula. Decide whether a column holds decimals or percentages, and keep it consistent.
Decimals above one
Any decimal above 1 is a percentage above 100%. A growth factor of 1.15 is 115%, which is the same as a 15% increase. That is why "multiply by 1.15" and "add 15%" are the same instruction.
Rounding
Converting between a decimal and a percentage never loses precision on its own — it is a shift of the decimal point. Rounding creeps in only when the decimal itself repeats, such as 1/3 = 0.3333…, which is 33.33…% however you write it.
Common questions
- How do I convert a decimal to a percentage?
- Multiply by 100, which moves the decimal point two places right, then add the percent sign. 0.075 becomes 7.5%.
- How do I convert a percentage to a decimal?
- Divide by 100, which moves the decimal point two places left. 7.5% becomes 0.075.
- Why two places and not one?
- Because per cent means per hundred, and 100 is 10 squared. Each factor of ten moves the point one place, so a factor of a hundred moves it two.
- Is 0.5 the same as 0.5%?
- No, and this is the most expensive mistake in the pair. 0.5 is 50%. 0.5% is 0.005 — a hundred times smaller.