Money Tools

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Thirty-five calculators for borrowing, saving, earning and spending

What a loan really costs once the fees are in it, how long a card balance takes to clear at the payment you are actually making, what one extra payment a month does to a mortgage, and whether refinancing saves money or only moves it. Then the other side: compound interest with the deposits going in, what a goal needs every month, and how long an emergency fund would last.

A budget that adds up and is compared with the income, two debt orders costed against each other, the subscriptions nobody adds up, and a net worth that says plainly when it is negative. An hourly rate turned into a salary and back, overtime at whatever the contract says, a rise measured against inflation, and what an hour of a meeting costs the people sitting in it.

None of the arithmetic is done in floating point, and no tool here names a currency: the money is in whatever currency your numbers were in, because a calculator that guessed would be wrong for almost everybody. Everything runs inside this browser tab, compiled to WebAssembly — which matters more here than anywhere else, because the numbers are a salary and a balance.

Saving

Simple interest
Interest that does not compound, and any three of the four give the fourth.

Savings goal
How much to put by each month, or how long it will take.

Emergency fund
Three to six months of expenses, and where that number comes from.

Inflation
What a sum will buy later, and what a later sum would have to be.

Rule of 72
The estimate everybody has heard of, beside the logarithm it approximates.

Borrowing

Credit card payoff
How long a balance takes to clear, and what a minimum payment never clears.

Loan comparison
Several offers side by side, where the cheapest is rarely the smallest payment.

Down payment
The deposit, what it leaves to borrow, and what that does to the payment.

Daily interest
Interest for an exact number of days, in whichever convention the contract names.

Budget

Monthly budget
A month's categories pasted in, added up and set against the income.

50/30/20 rule
Income split into needs, wants and saving, with the actual amounts beside it.

Net worth
What is owned less what is owed, from a pasted balance sheet.

Subscriptions
Everything on one period, because a yearly and a monthly one are not comparable.

Earning

Overtime pay
Overtime, night, weekend and holiday hours at their own rates.

Pay raise
A rise, and whether it is a rise once inflation is taken off.

Freelance rate
What an hour has to be worth, once the unbillable hours are counted.

Cost of living
What a salary has to be somewhere else to live the same way.

Meeting cost
What an hour of a room full of people costs, and what a weekly one costs a year.

Buying

Home affordability
The price an income and a deposit will reach, with the other debts in it.

Car affordability
What a monthly budget reaches once fuel, insurance and servicing are in it.

Rent or buy
Both sides costed over time, including what the deposit would have earned.

Lease or buy
A lease hands the car back; a purchase keeps it, and that is the whole difference.

Living costs

Fuel cost
What a journey costs in fuel, split between whoever is in the car.

Cash counter
Notes and coins counted into a total, against what should be there.

Payment code
A scannable payment code from an account and an amount, in the two standards that are plain text.

Questions

Why does the annual percentage rate differ from the interest rate?
Because the fees are in one and not the other. A rate is what the balance is charged; an annual percentage rate is the rate that would produce the same payments if the fee had been interest all along. It exists to compare two offers, and only against another one worked out the same way — it is not what the loan costs. The cost of credit is what the loan costs, and both numbers are shown.
Should I pay the smallest debt first or the dearest?
The dearest costs less, and both orders are costed here so the difference is a number rather than an argument. The other half of it is not arithmetic: clearing a debt outright is the thing people actually keep doing, and an order somebody sticks to beats a cheaper one they abandon. This tool gives both totals and no advice.
Which currency do these use?
None. The money is in whatever currency your numbers were in, and no tool names one anywhere — a symbol the application guessed at would be wrong for most visitors, and wrong beside a right number is worse than absent. Nothing here converts between currencies either, because that needs a rate from a network and these tools make no network requests.
Is anything I type uploaded?
No. The tools are compiled to WebAssembly and run inside the browser tab. Nothing you type is sent to a server, and you can watch your browser's network panel while you use one to see that nothing leaves the page. That is worth more here than elsewhere: these are salaries, balances and debts.