Tax Calculator

Adding tax is easy — removing it is where people slip

Adding a tax rate is a straightforward percentage increase. Removing one is not a percentage decrease, and treating it as one is the classic error. If a total of 1,416 includes 18% tax, taking 18% off 1,416 gives 1,161.12, which is wrong. The tax was calculated on the smaller pre-tax figure, not on the total, so you have to divide by 1.18 instead. The correct answer is 1,200.

The second tab handles that division for you, which matters whenever you are pulling a net figure out of a gross one for bookkeeping or an expense claim.

How to use it

Use Add tax when you have a net price and need the gross. Use Remove tax when you have a gross total — a receipt, an invoice, a ticket price — and need the net amount and the tax portion separately. Both tabs show all three numbers: net, tax and gross.

The formulas

Adding taxTotal = Amount × (1 + Rate ÷ 100)

Removing taxAmount before tax = Total ÷ (1 + Rate ÷ 100)

The tax portionTax = Total − Amount before tax

Worked examples

Adding 18% tax to a 1,200 invoice

Tax: 1,200 × 0.18 = 216
Total: 1,200 + 216 = 1,416

Removing 18% tax from a 1,416 receipt

The total represents 118% of the net amount
Net: 1,416 ÷ 1.18 = 1,200
Tax included: 1,416 − 1,200 = 216

This is arithmetic, not tax advice Which rate applies to a given product, in a given place, at a given time is a question for your tax authority or your accountant. This tool applies whatever rate you enter and nothing more — it does not know your jurisdiction, and it is not a substitute for professional advice.

Common mistakes

Subtracting the rate from a gross figure. Covered above: divide by 1 + the rate, never subtract the percentage from the total.

Rounding at every line. Rounding each line of a long invoice before summing can drift a few units away from the correct total. Keep full precision until the final figure.

Mixing inclusive and exclusive prices. Some price lists quote tax-inclusive figures and some do not. Establish which you are holding before you start adding or removing anything.

Frequently asked questions

How do I add 18% tax to a price?

Multiply the price by 1.18. For any rate, divide it by 100, add 1, and multiply — so 5% tax means multiplying by 1.05.

How do I remove tax from a total?

Divide the total by 1 plus the rate as a decimal. To strip 18% from 1,416: 1,416 ÷ 1.18 = 1,200. Do not subtract the percentage from the total.

Why can't I just take 18% off the total to remove the tax?

Because the tax was worked out on the smaller pre-tax amount. Taking 18% off the larger total removes too much — you would get 1,161.12 instead of the correct 1,200.

Does this work for VAT and GST?

Yes. VAT, GST and sales tax are all percentage rates applied to a price, so the arithmetic is identical. Enter whichever rate applies to you.

Can I use it for compound taxes?

For taxes applied one after another, run the calculator twice: add the first rate, then add the second to that result. For separate taxes applied to the same base, calculate each from the original amount and add them.

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