Launching today
Debt vs. Invest Calculator
Should you pay off debt or invest? Find out after taxes.
8 followers
Should you pay off debt or invest? Find out after taxes.
8 followers
Most calculators compare debt rates to investment returns before taxes. That's often the wrong answer. A 5% HYSA vs. a 4% car loan looks like a +1% win. After taxes, it can become **-0.40%**—meaning paying off the loan wins. This calculator uses 2026 U.S. tax rules, including federal brackets, NIIT, HYSA/T-Bills/stocks/IRAs, car & student loan deductions, mortgage rules, state tax treatment, and shareable links. Free. Open source. No signup. Feedback welcome.
would love to see a way to model multiple debts side by side, so i can see whether paying extra on the car loan vs. the student loan vs. the mortgage gives the biggest after-tax benefit given the specific deduction rules for each.
@erkansulumutlu Great suggestion Erkan — multi-debt comparison is on the roadmap.
The tricky part is the phase-out interactions when you have
both a student loan and mortgage simultaneously. Will build it.
Love that it bakes in NIIT and the car loan deduction rather than just doing the naive rate comparison, that is exactly the kind of detail most calculators gloss over and it makes the results actually trustworthy.
@muratzgirgr6bi Thanks — that was exactly the goal. Most tools do naive rate comparison. The NIIT threshold alone flips the math for high earners completely.