Calculators that keep your numbers to yourself

Loan payments, payoff strategies, rent-vs-buy scenarios and savings projections — computed instantly on your device. Nothing you type here is ever sent anywhere.

Calculators

Keeping track of what goes out each month? The Expense Tracker holds a year of recurring bills, subscriptions and purchases, with a dashboard by category, month and week, and exports to CSV, Excel and PDF.

Currency Changes the symbol only — no conversion is applied.

Loan calculator

Work out the monthly payment and total cost of any fixed-rate loan — car, personal, or student. Read the guide →

Loan amount ($)

Interest rate (% APR)

Term (years)

Monthly payment—

Total interest—

Total repaid—

Mortgage calculator

Estimate your full monthly housing cost — principal & interest plus taxes, insurance, and HOA. Read the guide →

Home price ($)

Down payment ($)

Interest rate (% APR)

Term (years)

Property tax ($/year)

Home insurance ($/year)

HOA ($/month)

Monthly total—

Principal & interest—

Loan amount—

Total interest—

Mortgage extra payment calculator

See what paying a little more each month does to your payoff date and lifetime interest. Read the guide →

Current balance ($)

Interest rate (% APR)

Years remaining

Extra per month ($)

One-time extra payment ($)

Extras start at month

Interest saved—

Time saved—

New payoff—

Monthly payment—

Interest without extras—

Interest with extras—

Debt payoff planner — avalanche vs snowball

List your debts, add whatever extra you can pay each month, and compare the two classic payoff orders. Read the guide →

Extra per month ($)

Avalanche targets the highest interest rate first — mathematically cheapest. Snowball clears the smallest balance first — slower but the early wins help some people stick with it. Both roll each freed-up minimum payment into the next debt.

Rent vs buy calculator

A scenario model, not a prediction: it compares your likely wealth if you buy versus if you rent and invest the difference. Read the guide →

Home price ($)

Down payment ($)

Mortgage rate (%)

Mortgage term (years)

Closing costs (% of price)

Property tax (%/yr)

Home insurance ($/yr)

HOA ($/mo)

Maintenance (%/yr of value)

Home appreciation (%/yr)

Selling costs (% of value)

Rent ($/mo)

Rent growth (%/yr)

Renter insurance ($/mo)

Investment return (%/yr)

Time horizon (years)

Better after 10 yrs—

Buy — net wealth—

Rent + invest — net wealth—

Break-even—

Assumes the renter invests every dollar they don't spend on housing (including the down payment and closing costs) at the return you set. Appreciation and returns are assumptions you choose — not forecasts. Taxes and deductions aren't modelled.

Loan refinance comparison

Compare keeping your current loan against refinancing, including the costs of doing it.

Current balance ($)

Current rate (% APR)

Years remaining

New rate (% APR)

New term (years)

Closing costs ($)

Costs paid

Break-even—

Monthly change—

Current payment—

New payment—

Future interest — keep—

Future interest — refi—

Interest already paid on your current loan is sunk and excluded — only costs from today forward are compared. A longer new term can lower the payment while raising total interest, so check both tiles.

Credit card payoff calculator

How long a revolving balance really takes to clear — and what paying more would do.

Balance ($)

Interest rate (% APR)

Monthly payment ($)

New charges ($/mo)

Payoff time—

Total interest—

Total paid—

Savings goal & compound growth

Project what your savings become — or work backwards from a target to the monthly amount it needs.

Starting balance ($)

Monthly contribution ($)

Assumed return (%/yr)

Years

Increase contribution (%/yr)

Final balance—

You contribute—

Growth—

Returns are compounded monthly from the rate you enter. Assumed returns are hypothetical — real markets vary year to year and this is not investment advice.

BMI calculator

Body mass index from your height and weight, with the healthy weight range for your height. Read the guide →

Height (cm)

Weight (kg)

Your BMI—

Category—

Healthy range for your height—

BMI is a screening measure, not a diagnosis — it doesn't account for muscle mass, age, or body composition. Talk to a healthcare provider about what's right for you.

Private by design, like every Toolsfully tool

These calculators are plain JavaScript running on this page. The numbers you enter — your loan size, your income assumptions, your weight — are processed in your browser's memory and never transmitted, logged, or stored. Refresh the page and they're gone.

The loan and mortgage calculators use the standard amortization formula for fixed-rate loans, so results match what banks and lenders quote for principal & interest. Actual mortgage offers add lender fees, PMI (usually required below 20% down), and rate variations — treat these numbers as a solid starting estimate, not a quote.

The payoff, refinance, rent-vs-buy and savings tools are scenario models: they simulate month by month using the assumptions you enter, and show you how the outcome changes when those assumptions change. They can't predict interest rates, house prices or investment returns, and nothing here is financial advice — but they'll show you the shape of a decision far better than a single number from a search result.