About MoneyMath

MoneyMath is a collection of free money calculators built on three promises:

1. Instant answers. No sign-up, no email gate, no "download your results" upsell. Type numbers, get answers.
2. Your numbers never leave your device. Every calculator runs entirely in your browser. We have no server that sees your salary, debts, or savings — there is literally nothing for us to store or sell.
3. We show the math. Every tool explains its formula, shows a worked example, and states its assumptions, so you can check our work.

Who this is for

Anyone making an everyday money decision: comparing a job offer, planning a raise negotiation, deciding whether to pay off a loan early, figuring out what rent fits a paycheck. These are five-minute questions that deserve five-second answers.

What we are not

We're not financial advisors, and no calculator here is financial advice. Calculators simplify. Tax rates vary, life happens, and a formula can't know your situation. For big decisions — buying a home, retirement planning — use our tools to understand the shape of the numbers, then talk to a qualified professional.

How we build and check our calculators

Every formula on this site comes from the standard, publicly documented math behind it — amortization schedules, IRS/CFPB guidance on things like withholding and mortgage disclosures, and well-established personal-finance rules of thumb (the 4% withdrawal rule, the 28/36 mortgage rule, and similar). Where a rule of thumb is a convention rather than a law of math, we say so and name the source, instead of presenting it as more certain than it is.

Tool descriptions and explanatory articles on this site are drafted with AI assistance and reviewed for accuracy before publishing. We'd rather tell you that plainly than pretend otherwise. What we stand behind either way: the formula is correct, the worked example is correct, and the assumptions are stated — not hidden in fine print.

We don't accept payment to favor one product, lender, or provider in a calculator's results. Where a page recommends a type of account or provider, that recommendation isn't for sale.

Corrections and freshness

Every calculator page shows a "last updated" date. If you find an error — a wrong formula, an outdated rate, a confusing explanation — email us. We fix real errors fast, and we'd genuinely rather hear about a mistake than have it sit there.