Money questions rarely have one number as an answer. What a loan costs depends on the rate, the term, and whether you pay a little extra each month; what a sale price saves you depends on how the discounts stack. These four calculators show the working, not just the result, so you can see which input is actually driving the answer.
Which one do you want?
| If you are… | Use |
|---|---|
| Buying a home | Mortgage Calculator — it includes taxes, insurance and PMI, which are usually 25–30% of the real payment. |
| Car loan, personal loan, or comparing offers | Loan Calculator — monthly payment and lifetime interest for any fixed-rate loan. |
| Saving or investing over years | Compound Interest — shows how much of the final balance is growth rather than what you paid in. |
| Working out a sale price | Discount Calculator — handles stacked "extra % off" deals, which do not add up the way they look. |
Every calculator here publishes the formula it uses and the date the reference figures were last checked. Nothing on this page is financial advice — it is arithmetic you can verify.
The mistakes these calculators exist to catch
- Reading the rate instead of the APR. Two loans advertising the same interest rate can cost different amounts, because APR folds in origination fees and points and the rate does not. On a mortgage the gap is routinely a quarter of a percentage point, which over 30 years is tens of thousands of dollars.
- Budgeting principal and interest as if it were the payment. On a US mortgage, property tax and insurance are usually escrowed into the monthly bill. A payment quoted as P&I alone can be 20–30% below what actually leaves your account.
- Assuming an extra payment saves its own value. It saves far more. A single extra payment early in a 30-year loan removes every future interest charge on that principal — which is why the amortization schedule, not the monthly figure, is where the decision gets made.
- Treating compound growth as linear. Money doubles at roughly 72 ÷ rate years. At 7% that is a decade; at 3.5% it is two. Over 30 years the 7% pot ends up about 2.7 times the 3.5% one — not the 2x that doubling the rate suggests.
Frequently asked questions
Do these use current interest rates?
No — you enter the rate. Rates move constantly and vary by lender and credit profile, so a calculator that guessed one for you would be worse than useless. Use the rate you were actually quoted.
Why does the mortgage figure differ from my lender's?
Usually escrow. Lenders quote principal and interest; your actual bill adds property tax, homeowners insurance, PMI below 20% equity, and any HOA dues. Our calculator adds all of them.
Are the results stored anywhere?
No. Every calculation runs in your browser and nothing is sent to us — close the tab and it is gone.