About Masspoint

A clear model, kept small.

Masspoint is an independent free calculator for one task: combining entered positive point masses and signed planar coordinates into a centre of mass. It is intended for small layouts, mock-ups, educational checks and keeping a readable calculation record. It asks for no registration or subscription.

What is included

The calculation uses exact rational arithmetic for entered decimals and fractions. It records total mass, two weighted coordinate sums and the resulting x/y centre. A schematic connects each numbered point to the table. Reports carry the current units, every input row and the model assumptions.

The formulas are referenced in the guide, alongside original worked examples. The examples and website code are original; this site is not affiliated with OpenStax, NIST, Cloudflare or Google. A reference link identifies a mathematical or conversion source, not an endorsement.

Useful limits

There is one calculator, with at most 30 entered rows. It does not find the internal mass centre of an arbitrary shape, compute support reactions, choose attachments or simulate movement. A geometry diagram cannot establish those properties. Tell the model which masses and mass-centre positions you want included.

Corrections

For a calculation issue, send the exact rows, units, expected result and reasoning to yardfill.helpful594@aleeas.com. For a display issue, include the affected page and browser. This is a shared public forwarding alias used by the owner's free-tool sites. There is no new mailbox or account attached to using this calculator.

Published model arithmetic can be exact while real measurements remain uncertain. We aim to make that distinction visible in both the result and saved report.