Standard Deviation Calculator

Calculate probability, combinations (nCr), permutations (nPr) and independent events with formulas and step-by-step working

Calculate percentages easily — find X% of a number, percentage change, increase and decrease. Four calculators in one tool.

Calculate volume in cubic feet from length, width and height. Supports feet, inches, cm, metres and yards with conversions to litres, gallons and more

Calculate the area of rectangles, circles, triangles, trapezoids, ellipses and parallelograms. Shows formula and step-by-step working