Three everyday number calculators
This page brings together three small calculation tools that cover most everyday situations where you need a reliable figure without opening a spreadsheet. Each works instantly in your browser: you enter your values, the result appears without a submit button or page reload, and no data is sent or stored.
The percentage calculator answers the three classic questions: what is a given percentage of a value (for example 20 % of 250), what percentage one value is of another (45 out of 180, for instance), and what the percentage change is between two numbers, such as the evolution of a price or bill from one month to the next. It is the most useful tool for decoding sales, newspaper statistics or a salary increase announced as an absolute amount.
The VAT calculator switches between a price excluding tax and a price including tax, and vice versa. You choose the applicable rate — 20 %, 10 %, 5.5 % or 2.1 % in France — and the tool breaks down the amount: ex-tax share, VAT amount and total including tax. Self-employed people use it for invoicing, consumers for checking a bill or estimating the real price of an item displayed ex-tax on a professional website.
Understanding a loan instalment
The instalment calculator estimates the amount to repay each month for an amortising loan: you enter the borrowed capital, the annual interest rate and the term, and the tool applies the standard constant-annuity formula used by banks. The result gives the monthly payment excluding insurance, as well as the total interest cost over the whole term — a figure often more telling than the rate itself when comparing two offers.
A few pointers for reading the result: lengthening the term reduces the monthly payment but greatly increases the total interest cost, because you repay the capital more slowly. Conversely, a short term costs less overall but requires a higher monthly repayment capacity. The simulator lets you test several combinations in seconds to find the balance that fits your budget. Bear in mind that a real bank offer also includes borrower insurance and possibly arrangement or guarantee fees, which are not included here.
When to use each calculator
Use the percentage calculator for anything expressed as a proportion: discounts, market share, absence rates, product composition. Use the VAT calculator whenever a price can be shown ex-tax or including tax, typically in commerce and invoicing between professionals. Use the instalment calculator before any credit commitment — mortgage, consumer loan, car loan — to check that the monthly burden remains compatible with your income: the usual French bank rule limits debt to about 35 % of net income, including insurance.
Frequently asked questions about the calculators
Are the calculations accurate?
Yes. The formulas applied are standard: rule of three for percentages, official coefficients for VAT, and the constant-annuity formula for instalments. Results are rounded to two decimal places for display, which may create a one-cent difference compared with a real invoice.
Which VAT rate should I choose?
In mainland France the standard rate is 20 %. The intermediate rate of 10 % applies mainly to restaurants and renovation work, the reduced rate of 5.5 % to basic food products, and the special rate of 2.1 % to certain medicines and publications. If in doubt, the rate is shown on the supplier's invoice.
Does the calculated instalment include borrower insurance?
No. The calculator gives the payment excluding insurance, calculated only on the capital and the nominal interest rate. A real loan offer adds insurance, expressed as an annual effective insurance rate (TAEA), and sometimes arrangement or guarantee fees.
How do I calculate a 30 % discount on an item priced at €89?
Using the percentage calculator: 30 % of €89 is €26.70 discount, so the final price is €62.30. You can also use the change between two values to check the percentage actually applied at the till.
Are my numbers sent or stored?
No. All calculations are performed locally in your browser in JavaScript. No entered value is sent to a server or kept after the page is closed.