Geometry & Measurement Calculators

Compute triangle area three ways — ½×b×h, Heron's formula from three sides, or ½ab·sin(C) — with the formula shown and an impossible-triangle check.

Enter any two sides of a right triangle and get the third, with the theorem substituted for your values and common Pythagorean triples.

Enter radius, diameter, circumference, or area to compute all other circle properties instantly with the formulas shown.

Enter a radius and height to get the volume (πr²h), lateral surface, base area and total surface area.

Enter the number of sides and one side length to get the area, perimeter, apothem, circumradius, and interior/exterior angles.

Compute triangle area three ways — ½×b×h, Heron's formula from three sides, or ½ab·sin(C) — with the formula shown and an impossible-triangle check.

Enter two sides and the included angle (Law of Cosines) or a side and two angles (Law of Sines) to get the missing side.

Enter any two sides of a right triangle and get the third, with the theorem substituted for your values and common Pythagorean triples.

Enter any two of the two legs and the hypotenuse to get all three sides, both acute angles, the area and the perimeter.

Enter the base and either the equal leg length or the height to get the apex angle, base angles, area and perimeter.

Enter one side length to compute the height (√3/2)s, area (√3/4)s², perimeter, inradius and circumradius.

Enter a radius and a central angle in degrees to get the sector area, arc length, chord length and the sector's perimeter.

Enter a radius and central angle to get the arc length, the sector area it bounds, and the straight chord between its endpoints.

Enter a length and width to get the area, perimeter and diagonal length of a rectangle.

Enter both parallel bases and the perpendicular height to get the area and median — add the legs to also compute the perimeter.

Enter the base and perpendicular height to get the area; add the slanted side to also get the perimeter.

Enter both diagonals to get the area (½d₁d₂), the equal side length and the perimeter.

Enter the number of sides and one side length to get the area, perimeter, apothem, circumradius, and interior/exterior angles.

Choose a shape and enter its dimensions to get the face or space diagonal, with the formula shown.

Enter a side length to get the volume (s³), surface area (6s²), face diagonal and space diagonal.

Enter a radius and height to get the volume (πr²h), lateral surface, base area and total surface area.

Enter a base radius and height to get the volume (⅓πr²h), slant height, lateral area and total surface area.

Enter the radius to get the volume (4/3 πr³), surface area (4πr²), diameter and great-circle circumference.

Enter a base area and height, choose prism or pyramid, and optionally add the base perimeter to also get the surface area.

Enter three side lengths to get the perimeter, semi-perimeter and area, with the triangle inequality checked for you.

Enter a base and area, or two sides and the included angle, to get the triangle's height with the formula shown.

Enter three side lengths to get the area via Heron's formula, with the semi-perimeter and every substitution written out.

Enter the three sides to get each median length via the median-length formula mₐ = ½√(2b² + 2c² − a²).

Enter three vertices to get the centroid — the average of the three points — drawn on a coordinate plane with the triangle.

Enter three vertices to get the circumcenter and circumradius, with the circumcircle drawn through all three points.

Enter three vertices to get the incenter and inradius, with the inscribed circle drawn inside the triangle.

Enter the three sides to get the circumradius via R = abc/4K, where K is the triangle's area.

Enter the three sides to get the inradius via r = K/s — the area divided by the semi-perimeter.

Enter a rectangle's length and width to get its diagonal (√(l² + w²)), plus the area and perimeter.

Enter a square's side to get its diagonal (s√2), with the area, perimeter and the 45-45-90 relationship shown.

Enter the two diagonals of a kite to get its area — half their product — with the perpendicular diagonals drawn.

Enter the semi-major and semi-minor axes to get the ellipse's area via A = π a b.

Enter the semi-axes to get the ellipse's perimeter via Ramanujan's approximation, with the method clearly labelled.

Enter the outer and inner radii to get the ring's area via A = π(R² − r²), plus both circumferences.

Enter a radius and either the central angle or the perpendicular distance to get the chord length, with the arc length alongside.

Enter a circle's radius and a chord length to get the perpendicular distance from the centre to that chord.

Enter a central angle to get the inscribed angle that subtends the same arc — always exactly half.

Enter a radius and arc length, or an inscribed angle, to get the central angle in both degrees and radians.

Compute triangle area three ways — ½×b×h, Heron's formula from three sides, or ½ab·sin(C) — with the formula shown and an impossible-triangle check.

Enter two sides and the included angle (Law of Cosines) or a side and two angles (Law of Sines) to get the missing side.

Enter any two sides of a right triangle and get the third, with the theorem substituted for your values and common Pythagorean triples.

Enter any two of the two legs and the hypotenuse to get all three sides, both acute angles, the area and the perimeter.

Enter the base and either the equal leg length or the height to get the apex angle, base angles, area and perimeter.

Enter one side length to compute the height (√3/2)s, area (√3/4)s², perimeter, inradius and circumradius.

Enter a radius and a central angle in degrees to get the sector area, arc length, chord length and the sector's perimeter.

Enter a radius and central angle to get the arc length, the sector area it bounds, and the straight chord between its endpoints.

Enter a length and width to get the area, perimeter and diagonal length of a rectangle.

Enter both parallel bases and the perpendicular height to get the area and median — add the legs to also compute the perimeter.

Enter the base and perpendicular height to get the area; add the slanted side to also get the perimeter.

Enter both diagonals to get the area (½d₁d₂), the equal side length and the perimeter.

Enter the number of sides and one side length to get the area, perimeter, apothem, circumradius, and interior/exterior angles.

Enter a side length to get the volume (s³), surface area (6s²), face diagonal and space diagonal.

Enter a radius and height to get the volume (πr²h), lateral surface, base area and total surface area.

Enter a base radius and height to get the volume (⅓πr²h), slant height, lateral area and total surface area.

Enter the radius to get the volume (4/3 πr³), surface area (4πr²), diameter and great-circle circumference.

Enter a base area and height, choose prism or pyramid, and optionally add the base perimeter to also get the surface area.

Choose a shape and enter its dimensions to get the face or space diagonal, with the formula shown.

Enter a rectangle's length and width to get its diagonal (√(l² + w²)), plus the area and perimeter.

Enter a square's side to get its diagonal (s√2), with the area, perimeter and the 45-45-90 relationship shown.

Enter three side lengths to get the perimeter, semi-perimeter and area, with the triangle inequality checked for you.

Enter a base and area, or two sides and the included angle, to get the triangle's height with the formula shown.

Enter three side lengths to get the area via Heron's formula, with the semi-perimeter and every substitution written out.

Enter the three sides to get each median length via the median-length formula mₐ = ½√(2b² + 2c² − a²).

Enter three vertices to get the centroid — the average of the three points — drawn on a coordinate plane with the triangle.

Enter three vertices to get the circumcenter and circumradius, with the circumcircle drawn through all three points.

Enter three vertices to get the incenter and inradius, with the inscribed circle drawn inside the triangle.

Enter the three sides to get the circumradius via R = abc/4K, where K is the triangle's area.

Enter the three sides to get the inradius via r = K/s — the area divided by the semi-perimeter.

Enter the two diagonals of a kite to get its area — half their product — with the perpendicular diagonals drawn.

Enter the semi-major and semi-minor axes to get the ellipse's area via A = π a b.

Enter the semi-axes to get the ellipse's perimeter via Ramanujan's approximation, with the method clearly labelled.

Enter the outer and inner radii to get the ring's area via A = π(R² − r²), plus both circumferences.

Enter a radius and either the central angle or the perpendicular distance to get the chord length, with the arc length alongside.

Enter a circle's radius and a chord length to get the perpendicular distance from the centre to that chord.

Enter a central angle to get the inscribed angle that subtends the same arc — always exactly half.

Enter a radius and arc length, or an inscribed angle, to get the central angle in both degrees and radians.