About DollarMathLab

DollarMathLab makes free calculators for the money decisions people actually face: whether to recast a mortgage, pay down debt or invest, and what a financing offer really costs.

What we believe

• Show the trade-off, not just a number. Most money decisions balance monthly cash flow against total cost. Our tools put the options side by side.
• Show the math. Each calculator explains the formula it uses, with a worked example you can check.
• Respect your privacy. Calculations run in your browser. No sign-up, and we don't store your inputs.

Accuracy and updates

We review our calculators when rules or limits change, such as new IRS contribution limits or Federal Reserve rate decisions. If you spot an error, please let us know and we'll fix it.

Disclaimer

DollarMathLab provides educational tools and general information only. Results are estimates based on the numbers you enter and standard formulas, and may differ from figures provided by your lender or tax professional. Nothing on this site is financial, tax or legal advice.