Everyday Math & Business Calculators
Some of the most useful calculators are the small ones you reach for every week: tipping at a restaurant, working out a discount, checking a price change, or converting miles to kilometers. These free tools give a quick, clear answer on any phone or computer. No sign-up.
Calculators in this category
Which calculator should I use?
- You are splitting a restaurant bill: Tip Calculator
- You want a percent of a number, such as a discount: Percentage
- You want the percent change between two numbers: Percentage Increase
- You are pricing a product: Margin
- You need to convert measurements: Unit Conversion
Margin and markup are not the same
Profit margin is profit divided by the selling price. Markup is profit divided by the cost. A product that costs $50 and sells for $100 has a markup of 100% but a margin of 50%. Mixing them up is a common pricing mistake.
For percent change, subtract the old value from the new value, divide by the old value, then multiply by 100. The percentage increase calculator does that for you.
Frequently asked questions
How do I calculate a percentage of a number?
Multiply the number by the percentage and divide by 100. For example, 15% of 80 is 12. The percentage calculator also handles increases and decreases.
How much should I tip?
Customs vary by country and place, so use the tip calculator to try different percentages and split the total between people.
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Estimates for education only, not financial advice.