Calculators tools
Calculators for everyday tasks: work out a discount, remove VAT from a price, solve a rule of three, get your grade average or add up the hours you worked this week. They show the working as well as the answer, so you can check it.
Percentage calculator
Discounts, increases, percent change and percent of a number.
VAT calculator
Add or remove VAT / sales tax from a price with a clear breakdown.
Finance calculator
Compound interest, loans, amortization and rate conversion.
Date calculator
Days between dates, business days, exact age and add days.
- New
BMI calculator
Body mass index with the WHO classification.
- New
Rule of three
Direct and inverse proportion solver with the working shown.
- New
Grade average calculator
Simple or weighted grade average and the score you still need.
- New
Hours calculator
Add up hours worked, add or subtract times and get your pay.
Practical guides
How to Make a Personal Budget
A step-by-step method for building a simple, realistic monthly budget you can actually keep, including how to use the 50/30/20 rule.
Compound Interest Explained
What compound interest is, how to calculate it, and why time, rate, and regular contributions change your final balance so much.
How to Calculate Percentages
Learn to find percentages, discounts, increases, and percentage change with simple formulas and clear everyday examples.
How to Calculate Business Days and Dates
The difference between calendar days and business days, when to include start and end dates, and how to avoid common date-counting errors.
A Basic Guide to Unit Conversion
Essential concepts for converting length, mass, volume, and temperature accurately, with the right factors and sensible rounding.