Free Online Calculators
Percentages, loans, interest, BMI, dates and units — answered instantly, with the working shown.
A calculator is only useful if you trust the number it gives you. That is why every calculator here shows its working: the formula it used, the intermediate steps, and — where it matters — a table or chart you can actually check. An answer you cannot verify is just a guess with a border around it.
Money. The Loan Calculator turns a principal, rate and term into a monthly repayment, the total interest you will pay over the life of the loan, and a full amortization schedule — the row-by-row breakdown that shows how little of an early repayment touches the principal. The Compound Interest Calculator runs the same maths in your favour, plotting how regular contributions grow over years. Use them together before signing anything: the same rate that costs you money on a loan earns it on savings.
Everyday arithmetic. The Percentage Calculator covers the three questions people actually ask — what is X% of Y, what percent is X of Y, and what is the percentage change between two numbers — including the reverse case that trips everyone up ("the sale price is $80 after 20% off; what was it before?"). The Unit Converter handles length, weight, temperature, volume, speed, time and data, which is the one you will end up bookmarking.
Health and time. BMI gives your body mass index with the WHO categories and the healthy weight range for your height; Calorie Calculator estimates maintenance calories from BMR and activity level. Date Difference counts days, weeks and business days between two dates, or adds and subtracts from one — the tool for notice periods, deadlines and visa windows.
Nothing you type is sent anywhere. The maths runs in the page, so your salary, your loan balance and your weight stay on your screen and nowhere else.
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Calculator FAQ
How do I work out a percentage decrease in reverse?
Divide, do not multiply. If an item costs $80 after a 20% discount, the $80 represents 80% of the original, so the original is 80 ÷ 0.8 = $100. Adding 20% back to $80 gives $96 and is wrong — a classic trap, because a percentage is always taken of a different base going up than coming down. The Percentage Calculator has a dedicated reverse mode that shows this step explicitly.
Is the loan calculator accurate enough to plan a mortgage with?
The amortization maths is exact — it is the same standard formula a bank uses, and the schedule will match theirs to the cent for a fixed-rate, monthly-repayment loan. What it cannot know are the extras: establishment fees, lender's mortgage insurance, offset accounts, rate changes and early-repayment penalties. Use it to compare scenarios and sanity-check what a broker tells you, not as a substitute for a formal quote.
Are my numbers private?
Completely. These calculators are plain JavaScript running in your browser — there is no form submission, no analytics on the values you enter, and no server that could log them even if it wanted to. Your income, debts, weight and dates are computed on your device and vanish when you close the tab.