About Marcus Runs the Math
Free calculators, plain-English explanations, no account required.
What this site is
Marcus Runs the Math is a free collection of money calculators: mortgage, loans, car loans, credit card payoff, savings plans, compound interest, paycheck take-home, and 401(k) growth. Each calculator shows the actual formula and a worked example, not just a black-box number, because understanding the math is the whole point.
Who's behind it
Marcus is the on-camera host and brand face of Marcus Runs the Math across video and social content. He is not a licensed financial advisor, accountant, or tax preparer, and nothing on this site should be read as a credential he doesn't hold. The calculators, written content, and this site are produced by the team at LDGMK Capital LLC, the publisher of this site.
How we keep the numbers right
- Every formula is a standard, publicly documented financial formula (amortization, future value of an annuity, marginal tax brackets). Nothing proprietary or hidden.
- Tax-year figures (2026 brackets, standard deductions, Social Security wage base, 401(k) limits) are sourced directly from the IRS and Social Security Administration, with sources listed on each relevant calculator page.
- Every calculator is covered by an automated test suite checked against independently verified reference numbers before anything ships.
This is education, not advice
Every number on this site is an educational estimate built from the inputs you provide and the assumptions stated on each page. It is not personalized financial, tax, or legal advice. Talk to a licensed professional for advice specific to your situation.
Educational estimates, not financial advice.