Math & Percentage Calculators

Percentage calculator with five modes plus scientific and fraction tools. Instant math results in your browser — free, no signup.

Calculate percentages five ways: percent-of, reverse, difference, increase, and decrease.

Calculate sale price after percent or dollar discounts, with optional stacked discounts and sales tax.

Find gross margin percent and dollar profit from cost and selling price, then compare with markup.

Set product markup on cost to get selling price and convert that markup into margin percent.

Analyze gross, operating, and net profit margins from revenue, COGS, and expenses.

Calculate return on investment as a percentage with optional annualized ROI and after-tax profit.

Find break-even units and revenue from fixed costs, variable cost per unit, and selling price.

Add, subtract, multiply, divide, and simplify fractions with mixed numbers and decimal equivalents.

Evaluate scientific expressions with PEMDAS, trig, logs, roots, and degree or radian mode.

Calculate mean, variance, and standard deviation for a dataset with population or sample mode.

Calculate room and floor area in square feet or square meters for rectangular and multi-room layouts.

Estimate concrete volume for slabs, footings, and columns in cubic yards and bags needed.

Generate cryptographically strong random integers or decimals in a custom range.

Roll standard RPG dice (d4–d20) or custom dice with quantity and modifiers.

Estimate how much paint you need for walls — cans, coverage with coats and waste, plus optional cost.

Calculate the mean, median, and mode of a number set, plus range, sample standard deviation, and variance.