Available now
Start with a focused tool
Live tools include the formula, a checked example, and documented assumptions.
Percentage Calculator
Find a percentage of any number and see the formula, substitution, and result.
Kinetic Energy Calculator
Calculate kinetic energy, or solve backward for mass or velocity, with visible formula steps.
Percentage Change Calculator
Find a percent increase, decrease, or unsigned difference from an original value to a new value.
Average Calculator
Add a list of numbers and divide by how many you entered to get the arithmetic mean.
Weighted Average Calculator
Combine values that should not count equally by dividing the weighted sum by the total weight.
Ratio Calculator
Simplify a ratio, scale it by a factor, or solve a missing term in a proportion a:b = c:d.
Fraction Calculator
Add, subtract, multiply, or divide two fractions, including mixed numbers, and reduce the result.
Decimal to Fraction Calculator
Convert a terminating decimal, or a repeating decimal, into a reduced fraction and explain the error if you stop early.
Scientific Notation Calculator
Rewrite a number as c × 10^e, expand scientific form, or add, subtract, multiply, and divide two scientific numbers.
Common tasks
What people use this collection for
- Find a share or a relative change
Use Percentage for “p% of n.” Use Percentage Change when a value moved from an original amount to a new one.
- Average a list, with or without weights
Average divides a sum by a count. Weighted Average multiplies each value by a weight first and reports whether those weights already sum to 1 or 100.
- Work in ratios, fractions, or powers of ten
Simplify a ratio or solve a missing term, operate on mixed numbers, convert a terminating or repeating decimal, or rewrite a number as c × 10^e.
Suggested path
A short math workflow
These links go only to published calculators or stay on this page as unlabeled steps.
Questions
About this collection
Which math tools are live today?
Percentage, Percentage Change, Average, Weighted Average, Ratio, Fraction, Decimal to Fraction, Scientific Notation, and Kinetic Energy. Each page is a separate intent; increase, decrease, and percent difference stay on Percentage Change as modes.
Do these calculators upload my numbers?
No. The current math tools calculate in your browser and do not send inputs to KE Calculator.