My Calculator Stack · Geometry formulas

Geometry · Formula sheet

Geometry formulas

One printable sheet for 12 Geometry tools — formulas collected from each calculator’s How it works.

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Area

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\[ A = \ell w \]

Multiply length by width.

Circle

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\[ A = \pi r^{2},\quad C = 2\pi r \]

Area uses π r²; circumference is 2 π r.

Cone Calculator

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\[ s=\sqrt{r^{2}+h^{2}},\quad S=\pi r(r+s),\quad V=\frac{1}{3}\pi r^{2}h \]

Compute slant height, then surface and volume.

Cylinder Calculator

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\[ V=\pi r^{2}h,\quad S=2\pi r(r+h) \]

Enter Radius (r) and Height (h) for the Cylinder Calculator; use finite values in the indicated domain. The calculator reports Surface and Volume: Cylinder volume πr²h and total surface 2πr(r+h). Radius and Height must share a length unit; area and volume use its square and cube.

Distance

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\[ d = \sqrt{(x_2-x_1)^{2}+(y_2-y_1)^{2}} \]

Apply the Pythagorean theorem to the coordinate differences.

Ellipse Area Calculator

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\[ A=\pi ab \]

Enter Semi-axis (a) and Semi-axis (b) for the Ellipse Area Calculator; use finite values in the indicated domain. The calculator reports Area: Ellipse area is π a b. Semi-major a and Semi-minor b are radii, not full axis lengths.

Polygon Angles Calculator

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\[ \sum=(n-2)180^\circ \]

Enter Number of sides (n) for the Polygon Angles Calculator; use finite values in the indicated domain. The calculator reports Interior sum (°), Each interior (°), and Each exterior (°): Interior sum (n−2)180°; exterior 360°/n. Number of sides must be a whole number of at least 3.

Pythogorean Theorem

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\[ c = \sqrt{a^{2}+b^{2}} \]

Take the square root of a² + b².

Regular Polygon Area Calculator

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\[ ap=\frac{s}{2\tan(\pi/n)},\quad A=\frac{ns^{2}}{4\tan(\pi/n)} \]

Area uses side length and apothem ap = s / (2 tan(π/n)).

Sphere Calculator

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\[ S=4\pi r^{2},\ V=\frac{4}{3}\pi r^{3} \]

Enter Radius (r) for the Sphere Calculator; use finite values in the indicated domain. The calculator reports Surface area and Volume: Surface 4πr² and volume 4/3 πr³. Radius must be nonnegative; Surface area uses squared units and Volume uses cubed units.

Surface

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\[ S = 2(\ell w + \ell h + w h) \]

Sum the three unique face areas and double.

Volume

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\[ V = \ell w h \]

Multiply length, width, and height.

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