About this calculator

A small, fast tool for one job: getting an exact chronological age onto an assessment protocol without arithmetic mistakes.

Why it exists

Clinicians and teachers calculate ages dozens of times a week, often between sessions, and the manual column method is easy to get wrong by a day or a month. Existing tools either stop at "how old am I" or hide the result behind ads and sign-ups. This site does the subtraction, shows the result in the Y;M;D format record forms use, offers both borrowing conventions found in test manuals, and can process a whole caseload at once.

How it works

Everything runs in your browser with plain JavaScript. The calculator uses the real calendar (including leap years) and the same column-subtraction method taught in assessment courses. No dates are sent to a server and nothing is stored except an optional list of your recent calculations in your own browser.

Accuracy and limitations

The arithmetic is deterministic and tested against hand-worked examples, but how an age is used (rounding, whether to correct for prematurity, which norm table to open) is defined by each test publisher. Always follow the manual of the test you are administering. If you find a result you believe is wrong, please tell us.

Contact

Email: hello@slpagecalc.com