Calculators
How to Calculate Percentage
Three percentage problems cover almost everything you will ever need: finding a percentage of a number, expressing one number as a percentage of another, and working out a percentage change.
4 min read
Guides
Short, practical explanations of the calculations people look up most — with the formula, a worked example and the traps to avoid. Each guide links to the VELNARO tool that does the maths for you.
Business
How to Calculate Profit Margin
Profit margin tells you how much of every unit of revenue your business keeps. Learn the three margins that matter, and why markup is not the same thing.
5 min read
Finance
How to Calculate ROI
Return on investment is the simplest way to compare what you put in with what you got out — and annualising it is what makes different timescales comparable.
4 min read
Health
How to Calculate BMI
Body mass index is a quick screening measure, not a diagnosis. Here is how it is calculated, what the categories mean, and where it falls short.
4 min read
Business
How to Calculate VAT
Adding VAT and removing VAT are not the same calculation. Learn both, plus why subtracting 16% from a gross price gives the wrong answer.
4 min read
Finance
How to Calculate Compound Interest
Compound interest is growth on growth. Understand the formula, see how the compounding frequency changes the outcome, and why time beats rate.
5 min read
Converters
How to Convert KG to LBS
Kilograms to pounds is one of the most requested conversions in the world. Here is the exact factor, quick mental maths, and a ready reference table.
3 min read
Finance
How to Calculate Your Salary Per Hour
Turn an annual salary into a true hourly rate — accounting for unpaid leave, unpaid breaks and the hours you actually work.
4 min read
Finance
How to Calculate a Discount
Work out a sale price in one step, understand why stacked discounts do not add up, and check whether a "50% + 30% off" offer is what it looks like.
3 min read
Travel
How to Calculate Fuel Costs
Estimate what a journey costs in fuel, whether to use litres per 100 km or miles per gallon, and how to split the cost between passengers.
4 min read
Time
How to Calculate Working Days
Count business days between two dates for contracts, SLAs, notice periods and project plans — including weekends and public holidays.
4 min read