Personal finance calculators that show their work
Most calculators hand you a number and hide how they got it. Ours show the exact formula with your numbers plugged in, compare your options side by side, and explain what the result actually means — instantly, with no sign-up. Seventeen tools for loans, debt, saving and retirement. Built to be genuinely useful, not just to rank.
Saving & investing
Browse by topic
DRIP Calculator
The share count, not just the value — $25,000 reinvested turns 500 shares into 1,319 in 20 years.
Open calculator →Dividend Calculator
Dividend income, DRIP reinvestment growth, and rising yield on cost over time — with dividend growth and contributions.
Open calculator →Compound Interest
Project investment growth from contributions and time, with a contributions-vs-growth chart.
Open calculator →401(k) Retirement
Projected balance at retirement with employer match, salary growth and compounding — and how much is free match money.
Open calculator →Savings Goal Calculator
Time to reach a goal at your monthly amount — or the monthly amount needed to hit it by a date.
Open calculator →Coast FIRE Calculator
Find the age your invested money can coast to retirement on its own — the point you can stop saving.
Open calculator →Yield on Cost Calculator
Your real dividend yield on what you paid — and how dividend growth lifts it into double digits over time.
Open calculator →Coast FIRE for Couples
One household number for two people — with your age gap and different retirement dates handled properly.
Open calculator →Barista FIRE Calculator
How part-time income shrinks your FIRE number and the age you can leave full-time work — vs full FIRE.
Open calculator →Fat FIRE Calculator
The portfolio to retire on $100k+ a year — with your Lean, Regular and Fat FIRE numbers at any withdrawal rate.
Open calculator →Loans
Mortgage Calculator
Monthly payment with tax, insurance & PMI, total interest, payoff date, and a 15-vs-30-year comparison.
Open calculator →Auto Loan Calculator
Real car payment including sales tax and trade-in, total interest, and a 36-to-72-month cost comparison.
Open calculator →Personal Loan Calculator
Monthly payment, total interest, and the real APR once the origination fee is counted — the number lenders bury.
Open calculator →Mortgage Recast Calculator
Your new lower payment after a lump sum — and whether recasting or paying extra principal saves you more.
Open calculator →Debt payoff
Credit Card Payoff
How many months to clear your balance, total interest, and the true cost of the minimum-payment trap.
Open calculator →Debt Snowball vs Avalanche
Enter all your debts and see which payoff method clears them fastest and saves the most interest.
Open calculator →Big decisions
Guides
Debt Snowball vs Avalanche
Which method actually costs less, by how much, and why the cheaper one is the one most people quit — worked through with real numbers.
Read guide →The Minimum Payment Trap
Why minimum payments stretch a balance over two decades — and the one change that cuts it to a few years without paying more.
Read guide →How Much Does a Mortgage Recast Cost?
The fee is $150–$500 — but the real cost is what the lump sum gives up.
Read the guide →What Is a Good Yield on Cost?
There is no threshold — and the highest yield on cost is not the one that pays most.
Read the guide →Is a Mortgage Recast Worth It?
It lowers your payment without refinancing — but it will not shorten your loan. When it wins, and when extra principal beats it.
Read guide →Coast FIRE vs Barista FIRE
Two very different ways to stop saving early — what each one actually requires, and which fits your situation.
Read guide →Lean FIRE vs Fat FIRE
The spending levels that define each, the portfolio each needs under the 4% rule, and the risk trade-offs that matter.
Read guide →Why these are different
- Formula transparency. Every tool shows the real equation with your inputs — verify the math yourself.
- Scenario comparison. See your options side by side, not one number in isolation.
- Plain-language meaning. We explain what the result implies and what to do next.
- Fast & private. Instant results, no account, no email wall, no clutter.
All tools provide educational estimates, not financial advice. Confirm important figures with a qualified professional.