CALCULATORFUNCTION.COM
All finance calculators
66 free tools covering borrowing, investing, tax, retirement, property and business. Each one runs entirely in your browser, needs no account, and explains what the result actually means rather than just returning a number.
If you are not sure which tool fits, read the short introduction above each group below — most categories contain several calculators that look similar and answer meaningfully different questions.
Loan calculators
Work out what borrowing actually costs before you sign for it.
Every loan calculator here answers the same underlying question from a different angle: what does this debt cost in total, not just per month? Lenders quote the monthly instalment because it is the smallest and most reassuring number in the contract. The total interest is usually the one that changes your mind.
Start with the EMI calculator if you want the bare mechanics. Move to the specific tools — home, car, personal, education, business — when you want the framing and pitfalls particular to that kind of borrowing. If you already have a loan running, the prepayment and balance transfer calculators are the two that can save you real money on it.
Investment calculators
Project what regular or one-time investing could build over time.
These tools model growth over long periods, which is where compounding stops feeling theoretical and starts dominating the result. Every projection rests on an assumed rate of return, and that single input matters more than any other. Enter an optimistic figure and you get an optimistic plan that comes up short.
Use the SIP calculators for money invested monthly out of income, and the lumpsum or CAGR tools for a single amount or for measuring performance already achieved. The deposit and scheme calculators — FD, RD, PPF, NPS, EPF — cover products where the rate is set for you rather than assumed, so their outputs are firmer, though rates on government-linked schemes are reviewed periodically rather than fixed for life.
Interest calculators
The arithmetic underneath every savings product and every loan.
Simple and compound interest are the two mechanisms behind almost every financial product you will encounter. The difference between them looks trivial over a year and becomes enormous over a decade, which is why knowing which one applies to your money is worth more than shopping for a marginally better rate.
The simple and compound calculators here are the general-purpose versions. The monthly income and long-horizon savings scheme tools apply the same maths to specific products, where the trade-off is usually between drawing interest as income now and letting it compound instead.
Tax calculators
Estimate what you owe, and understand why the number is what it is.
Tax gets misunderstood more than any other area of personal finance, usually in the same way: people believe that moving into a higher slab taxes all their income at that rate. It does not. Only the portion above the threshold is charged at the higher rate, which is why earning more never leaves you worse off under a progressive system.
These tools are for orientation and budgeting, not for filing. Rates, slabs, thresholds and available deductions change with each budget cycle, and jurisdictions differ in how they treat capital gains, allowances and salary components. Treat any figure here as a starting point to check against current official rates.
Retirement calculators
Size the fund you will need, and track what you have built so far.
Retirement planning runs backwards from every other calculation on this site. Instead of asking what a contribution grows into, it asks how large a fund is needed to replace an income for the rest of your life, and then works back to what you must save to reach it.
The mistake that ruins most retirement plans is arithmetic rather than discipline: planning in today’s money. An income that feels comfortable now will not be comfortable after decades of inflation. Either inflate your spending estimate to your retirement date, or use a real return — your expected return minus inflation — and be consistent about which you chose.
Insurance calculators
Estimate how much cover the people depending on you would need.
Insurance calculations start from an uncomfortable question: if your income stopped permanently tomorrow, what would happen to the people who rely on it? The answer sets the cover amount. Working backwards from the premium you would prefer to pay is how households end up underinsured at exactly the moment it cannot be corrected.
The life and term calculators size cover from income replacement plus outstanding debts. The health calculator works differently — it is not about replacing income, but about ensuring that one serious hospitalisation does not consume savings built for something else. Buying early helps in both cases, since premiums are priced on your age and health at purchase and both move against you with time.
Real Estate calculators
Model property costs, growth, and the rent-versus-buy decision.
Property is the asset people are most confident about and most likely to model badly. Ownership carries costs that never appear in a price comparison — maintenance, property tax, insurance, society charges — plus substantial transaction costs at both ends that can consume years of notional gain.
The rent versus buy calculator is the one worth running honestly, because the usual framing is wrong. Rent is not simply wasted money: mortgage interest, property tax and maintenance are equally unrecoverable. The fair comparison is unrecoverable cost against unrecoverable cost, plus whatever your down payment would have earned elsewhere.
Business calculators
Pricing, margin and return calculations for running a business.
These tools answer the questions that decide whether a business is viable rather than merely busy. Break-even tells you the volume that covers your costs. Margin tells you how much of each sale survives the cost of delivering it. Return on investment tells you whether money spent actually came back.
The recurring error across all three is misclassifying costs — treating a variable cost as fixed, folding overheads into cost of goods, or leaving your own salary out of fixed costs entirely. Get the classification right and these calculations are reliable. Get it wrong and they are confidently misleading.
General calculators
Everyday calculations that come up outside financial planning.
Not every calculation is a financial decision. These are the everyday ones — percentages, dates, discounts, body mass index — that people reach for constantly and get subtly wrong just as often.
The percentage calculator is the one worth reading the notes on. A percentage increase and an equal decrease do not cancel out, stacked discounts multiply rather than add, and reversing a percentage requires division rather than subtraction. Each of those trips people up on real invoices and real shopping decisions.