Basic Math Calculators

Use 31 free online math calculators for arithmetic, percentages, algebra, calculus, geometry, statistics, probability, and unit conversion. Choose a category below to find the right math calculator.

Percentage, fraction, and everyday number tools

Most everyday math searches are percentage problems: discounts, tips, tax, exam scores, and change from an old value to a new one. Open the percentage calculator for those. Use the fraction calculator when the inputs are fractions rather than decimals.

Sales tax is a specialized percentage problem with a rate applied to a purchase. The unit converter is the right next step when the question is units rather than a percent.

Which everyday math tool to open

Use percentage for rates, fractions for fraction arithmetic
Calculator	Use it when you need
Sales Tax Calculator	Add or remove a sales-tax rate
Percentage Calculator	Percent of, reverse percent, and change
Fraction Calculator	Fraction arithmetic and simplification
Unit Converter	Length, weight, temperature, and more

Frequently asked questions

How do I calculate a percentage of a number?

Divide the percentage by 100 and multiply by the number. The percentage calculator does this in the “percent of” mode and can also reverse the question or measure change.

When should I use a fraction calculator instead?

Use the fraction calculator to add, subtract, multiply, divide, or simplify fractions. Convert to a percentage only after you have a decimal or fraction result you want to express per hundred.

Is sales tax the same as a percentage increase?

Sales tax is a percentage added to a price. Percentage change compares an old value with a new value and can be an increase or a decrease.