Math & numbers
Pick a tool below. Each page includes formulas, steps, and examples.
Basic
Percentage Calculator
Calculate percentages three ways: find X% of a number, find what percent one number is of another, or compute the percentage change between two values.
Ratio Calculator
Simplify ratios to their lowest terms and solve proportion problems (A:B = C:?). Shows the GCD, simplified ratio, and step-by-step calculation — free and instant.
Number Base Converter
Convert numbers between binary, octal, decimal, and hexadecimal instantly. Enter any value in one base and see all four representations at once. Free developer tool.