Units, conversions and calculators

Calculators of electricity, gas and fuel consumption and cost.

Construction calculators: concrete, bricks, plaster, paint, plasterboard, roofing, stairs and bulk materials.

Fraction arithmetic explained visually: addition, subtraction, multiplication, division and simplification.

Solve equations and inequalities step by step: linear, quadratic, systems and a general solver.

Area and perimeter of plane shapes: circle, triangles, quadrilaterals, polygons, ellipse and land plots.

Volume and surface area of solids: cube, cuboid, cylinder, cone, sphere, prism, pyramid and frustums.

Trigonometric functions explained: sine, cosine, tangent and more, including inverse functions. With the unit circle, graphs and real-world examples.

Powers and roots explained: squares, cubes, general powers, roots, scientific notation and calculation rules.

Logarithms explained: common, natural (ln), base-10 and binary. With graphs, rules, equation solving and real-world examples.

Derivatives and integrals made visual: tangent to a graph, area under a curve, Riemann sums, symbolic differentiation and formula references.

Calculate your body mass index (BMI) from height and weight. Separately for men and women, with body-fat estimate and healthy-weight range.

Interactive percentage calculations with sliders and live visualisation. What is X % of Y, what percentage is X of Y, percentage change.

Direct and inverse proportion solver with step-by-step explanation and a calculation history.

Arithmetic and weighted average with a dot-plot visualisation, median and range.