Six calculators that do the arithmetic personal finance advice usually leaves to you. Each one runs entirely in your browser — nothing you type is sent anywhere, and nothing is stored except on your own device, so you can close the tab and come back to it.
They are listed roughly in the order most people need them, though nothing stops you starting anywhere.
Subscription 1
Subscription audit
The average household pays for more subscriptions than it can name from memory, and the ones that go unused are rarely the expensive ones you would notice. List what you pay for, mark how often you actually use each service, and the audit totals the annual cost and flags the candidates for cancelling.
Emergency fund
Every guide says three to six months of expenses, and almost none of them say which. The honest answer depends on how steady your income is, how many people depend on it, and whether anyone else in the household earns. This calculator takes those, puts your target somewhere specific inside that range, and shows the score it used to get there — so if the answer looks wrong you can argue with an input rather than with a black box. It then works out how long filling it takes at what you can currently set aside.
Debt 1
Debt payoff
Two popular strategies disagree about which debt to clear first. The avalanche method targets the highest interest rate and costs you the least; the snowball method targets the smallest balance and gives you a win sooner. This calculator runs both against your actual debts, month by month, and shows what the difference is worth in interest and in time.
Savings goal
Saving for something specific raises one of two questions, and they are the same arithmetic run in opposite directions. If you know what you can put aside each month, you want the date. If you know the date, you want the monthly figure. This calculator answers both from one form, and switching between them keeps everything you have already typed. It also counts the interest earned along the way, which on a multi-year goal moves the answer more than most people expect.
Compound interest
Compounding is difficult to feel from a percentage. This calculator makes one thing visible: how much of the final balance you never put in. It charts your contributions against what the account is actually worth, and the widening gap between the two lines is the return doing the work. You can set how often you contribute, how often interest is added, and whether to show the result in today's money — a forty-year projection that ignores inflation flatters itself badly.
Financial independence (FIRE)
Financial independence arrives when your savings can cover your spending without you working. The arithmetic depends far more on the share of your income you keep than on how much you earn, which is not obvious until you see it. This calculator projects the date, and shows how much it moves when you change one assumption at a time.
About the numbers
Every calculator here shows the assumptions it is using and lets you change them. Default rates of return, inflation and withdrawal are conventions, not predictions — they are reasonable starting points, and the results move a great deal when they are wrong. Treat the output as a way to compare choices, not as a forecast, and speak to a qualified professional before acting on anything that matters.