About FreeFast Calculator

FreeFast Calculator publishes free calculators for questions that general calculator sites answer poorly or not at all. Every calculator runs entirely in your browser — nothing you type is sent to a server.

Who writes these pages

Every calculator and article is written and fact-checked by the FreeFast Calculator editorial team, using the process below. We are not doctors, veterinarians, electricians or financial advisers, so for health, pet, electrical and money decisions we point you to the official source and suggest you check with a professional.

How we build and check calculators

• No numbers from memory. Every formula, coefficient, table value, limit and date window is checked against the primary source before it goes on the site: the statute, the official table or the original paper. Where we can't verify a value, we remove it or label it on the page as an estimate or assumption.
• Primary sources first. Government bodies and statutes (NIST, IRS, OPM, DOL, FAA, NIH, UPSC, the Army, Marine Corps, Air Force and Navy), then standards and official bodies (NFPA, Unicode, College Board, IPF), then peer-reviewed research and university or veterinary references. We don't rely on blogs, other calculator sites or Wikipedia.
• At least two sources, linked exactly. Each calculator lists at least two institutional sources in its "Sources & method" section, linked to the specific page or PDF that shows the value, not a home page. Where only one authoritative source exists (for example, Wilton's cake serving chart), we say so.
• A written audit trail. We keep a research log with one line per fact: which calculator uses it, the value, the source, the exact link and the date we checked it.
• Shown working. Every page explains the formula and its assumptions so you can check the result by hand. FAQ answers are computed from the same code as the calculator, so the two always agree.
• Tested. Core formulas have automated checks against published reference values — for example the National Academies' own EER tables, and military score-table cells re-read from the official PDFs.
• Reviewed. Each page shows the date its content was last checked. Rules that change yearly (contribution limits, exam windows, fitness tables) are re-verified at least once a year.

Limits

Results are estimates for general information. They are not a substitute for a veterinarian, doctor, licensed electrician, tax professional, official exam body or your service's official fitness record. When a decision matters, confirm with the relevant professional or authority.

Corrections

If you spot an error or an outdated rule, tell us and we will fix it and update the review date.