Endpoint calculator

The missing endpoint equals twice the midpoint minus the known endpoint, component by component.

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Known endpoint x

Midpoint x

More inputs and assumptions

Known endpoint y

Midpoint y

Answer

…

The missing endpoint equals twice the midpoint minus the known endpoint, component by component.

More results

Precision and calculation record

Decimal places in numeric results and text downloads

Rounding changes displayed numbers, not the calculation. Text, fractions, matrices and CSV schedules keep their own formatting. Automatic keeps up to 12 significant digits, with money shown to cents where applicable.

Step-by-step calculation

Inputs are substituted below. Each line evaluates the next operation; intermediate values are displayed to 12 significant digits while the calculation uses full precision.

Saved scenario

Save the current answer, then change an input to compare. This clears when you leave.

Formula and assumptions

Enter coordinates in the same Cartesian coordinate system. The supplied midpoint is assumed to bisect the segment exactly.

Automatic precision shows numbers to 12 significant digits. Thousands separators such as 1,000 are accepted; use a dot for decimals.

Scratch calculator

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Updated 2026-09-26

Using Endpoint calculator

The missing endpoint equals twice the midpoint minus the known endpoint, component by component.

Enter coordinates in the same Cartesian coordinate system. The supplied midpoint is assumed to bisect the segment exactly.

Next: Basic calculator

A worked example

With known endpoint x = 1, midpoint x = 4, known endpoint y = 2, midpoint y = 6, the other endpoint x is 7.

Before you use the result

Enter coordinates in the same Cartesian coordinate system. The supplied midpoint is assumed to bisect the segment exactly.

Example results for known endpoint x

These examples use Midpoint x: 4; Known endpoint y: 2; Midpoint y: 6. They are reference calculations, not recommended settings.

Known endpoint x	Other endpoint x
0.5	7.5
1	7
2	6

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ToolOctopus. “Endpoint calculator.” Updated 2026-09-26. https://tooloctopus.com/endpoint-calculator.

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