10 calculators
Finance Calculators
These finance calculators help estimate monthly payments, total interest, housing costs, extra-payment savings, and pay conversions. They are designed for quick planning and comparison, with transparent formulas and editable assumptions.
Tools in this category
Guides for finance
Longer explanations for the questions a calculator form cannot answer on its own.
Which calculator answers which question
Finance questions split cleanly by what you already know and what you are missing. Match the sentence, then bring the numbers you have — every tool here works from figures printed on a statement, offer or payslip.
| What you are asking | Use | You need |
|---|---|---|
| What is the monthly payment on this loan? | Loan payment | amount, rate, term |
| What will this house actually cost per month? | Mortgage | price, down payment, rate, tax, insurance |
| What is the payment on a car with a trade-in? | Car payment | price, trade-in, rate, term |
| How long until this card is paid off? | Credit card payoff | balance, APR, monthly payment |
| What does this salary work out to hourly? | Salary converter | pay, hours per week |
| What lands in my account after deductions? | Take-home pay | gross pay, deduction rates |
| What will savings grow to over time? | Compound interest | principal, rate, years, contributions |
| What is the flat interest on this sum? | Simple interest | principal, rate, time |
| Am I on track to retire? | Retirement | current savings, contributions, target age |
| What margin am I making on this? | Profit margin | cost, selling price |
The formulas behind this category
Every amortised loan on this site — mortgage, car, personal — uses the same payment formula:
M = P × r × (1 + r)^n ÷ ((1 + r)^n − 1)
where P is the amount borrowed, r the rate per period (annual rate ÷ 12) and n the number of payments.
Compound growth: A = P × (1 + r ÷ n)^(n × t)
Simple interest: I = P × r × t
APY = (1 + r ÷ n)^n − 1
Gross margin % = (price − cost) ÷ price × 100
Markup % = (price − cost) ÷ cost × 100
Loan-to-value = loan ÷ property value × 100
Interest rate, APR and APY are three different numbers
Lenders and banks quote whichever of the three flatters them, so comparing offers means knowing which one you are looking at.
| Figure | What it includes | Where you see it |
|---|---|---|
| Nominal interest rate | the cost of the money only | the headline number in an advert |
| APR | interest plus lender fees, points and required charges | the legally disclosed cost of borrowing |
| APY (or AER) | interest plus the effect of compounding | savings and deposit accounts |
Two loans at the same 6% nominal rate can differ by thousands once origination fees enter the APR. On the savings side, 6% compounded monthly is an APY of 6.17% — the gap widens the more often interest is credited.
Why early payments barely touch the balance
Amortisation charges interest on the balance that is still outstanding, so the split between interest and principal shifts across the term even though the payment never changes. On a $250,000 loan at 6% over 30 years — $1,499 a month:
| Payment | Interest | Principal | Balance after |
|---|---|---|---|
| 1st | $1,250 | $249 | $249,751 |
| 60th (year 5) | $1,165 | $334 | $232,636 |
| 180th (year 15) | $891 | $608 | $177,622 |
| 360th (final) | $7 | $1,491 | $0 |
That front-loading is also why an extra payment made early is worth far more than the same payment made late: it removes principal that would otherwise have accrued interest for the whole remaining term.
Term length is a trade between payment and total cost
$25,000 borrowed at 7%, by term:
| Term | Monthly | Total interest |
|---|---|---|
| 24 months | $1,119 | $1,864 |
| 36 months | $772 | $2,789 |
| 48 months | $599 | $3,735 |
| 60 months | $495 | $4,702 |
| 72 months | $426 | $5,688 |
Stretching from three years to six cuts the monthly payment by 45% and doubles the interest. Neither answer is automatically right — but the comparison should be deliberate, not a by-product of the term the dealer typed in.
The rule of 72, and where it breaks
Divide 72 by the annual rate to estimate the years for money to double: at 6%, about 12 years. It is accurate to within a few months for rates between roughly 4% and 12%, and drifts noticeably outside that band — at 1% the real answer is about 70 years, not 72. The compound interest calculator gives the exact figure and shows why the gap against simple interest widens with time.
What these estimates cannot tell you
- Lender rules. Underwriting, credit scoring and minimum-income tests decide whether an offer exists at all.
- Fees outside the payment. Arrangement fees, valuation, legal costs and early-repayment charges sit outside the amortisation math.
- Variable rates. Every figure here assumes the rate holds for the full term; a tracker or adjustable loan will not.
- Local tax. Payroll and take-home figures depend on jurisdiction, allowances and filing status that a general calculator cannot know.
The formulas behind this category, and the published sources they come from, are listed on the methodology page.
Other categories
Finance — common questions
Are the finance results exact quotes?
No. They are planning estimates based on the values you enter. Real loan, mortgage, tax, and payroll outcomes can differ because of lender rules, fees, taxes, deductions, and local requirements.
What can I compare with these calculators?
You can compare loan terms, interest rates, down payments, extra payments, monthly housing costs, hourly wages, yearly salary, overtime, and rough net income.