Economy General Calculator
A collection of everyday economy calculators such as tax, exchange rate, and margin rate.
US Sales Tax Calculator
Estimate US state and local sales tax. Enter a pre-tax price and your combined rate (defau...
Read MoreCurrency Converter Calculator
Multiply a foreign amount by the exchange rate to get the local currency amount. Useful fo...
Read MoreMargin Rate Calculator
Enter cost and selling price to calculate the margin (profit) and margin rate (%) at the s...
Read MoreAbout This Category
Everyday business arithmetic: adding or removing sales tax, converting between currencies, and turning cost and price into a margin. The three connect more than they appear to, because a margin computed on price and a markup computed on cost are different numbers.
Each page states whether the figure is exclusive or inclusive of tax and whether the percentage is taken from the cost or the selling price, which is where most of the arguments about these numbers come from.
Frequently Asked Questions
Why is a 30 % margin not a 30 % markup?
A 30 % margin means profit is 30 % of the selling price, so the markup on cost is 42.9 %. A 30 % markup means profit is 30 % of cost, which is a 23.1 % margin.
How do I remove sales tax from a total?
Divide by one plus the rate. At 10 %, 110 becomes 100; subtracting 10 % of 110 gives 99, which is the common mistake.
Does the exchange-rate page fetch live rates?
No. Enter the rate you were quoted. A rate you cannot see the source of is worse than one you typed yourself.
Calculators in This Category
Sources & last update
2026-10-19