Editorial policy and disclaimer

How the calculators are built

Each calculator starts with a public formula or a published rule. I write the code, test it against worked examples and explain the formula on the page, so you can check any result by hand.

Where the numbers come from

Tax, payroll, health and loan figures come from official or widely trusted public sources:

• IRS: Tax brackets, standard deduction, payroll and self-employment rules
• CDC: BMI categories and healthy weight guidance
• Consumer Financial Protection Bureau: Mortgage, loan and credit guidance
• Social Security Administration: FICA, benefits and retirement figures
• National Institutes of Health: Sleep, nutrition and hydration research

How the guides are written

Guides are written in plain English for people who are not experts. Every claim about rules, rates or limits is checked against one of the sources above before it is published, and guides link to a calculator so you can try your own numbers.

Updates and corrections

Tax brackets, limits and rates change every year. I review the calculators when the rules change and show the review date on each page. If you spot a mistake, send a message and I will check it and fix it as soon as possible.

Advertising and independence

Tidy Math is free to use and is supported by advertising. Ads never change a calculation or a recommendation, and no advertiser pays for a better result or a better ranking. See the Privacy Policy for how ads and cookies work.

Disclaimer

The calculators and guides on Tidy Math are for education and planning. They are estimates, not financial, tax, legal or medical advice, and they cannot know your full situation. Check important decisions with a licensed professional, such as a tax preparer, financial adviser or doctor.