Tools · 7 client-side calculators

Calculators that show their work.

Interactive on the page, run entirely in your browser. Every result comes with the formula in words. No accounts, no email, no black boxes.

What the minimum on a credit card actually costs, vs a fixed monthly payment.

Avalanche vs snowball, side by side, on up to eight debts.

Years shaved and interest saved from a small extra payment each month.

Monthly total in one column, honest annual total in the next.

A range fitted to your essentials, income steadiness, and household earners — never one dogmatic number.

Contributions vs growth at 10, 20, and 30 years, at a hypothetical return you choose.

Two fund fees side by side. The dollar cost of the difference over decades.

Plumb is financial education, not financial, investment, tax, or legal advice.