Add Tax / VAT Calculator
Add tax or VAT to a price to get the total.
Enter your numbers
Formula
How the calculation works
Adding tax is one multiplication and one addition, but the base matters more than the arithmetic. The rate always applies to the pre-tax price, so 120 at 15% adds 18 and lands on 138. Tax is charged on what the seller receives, not on what you hand over, which is why the percentage can never be read back off the total directly.
The money grows with the price while the rate stays put. 15% of a 20 lunch is 3, and 15% of a 2,000 laptop is 300. The rate is identical and only the money moves, so two shoppers comparing tax rates are comparing the same number while two shoppers comparing tax paid are comparing very different ones.
Taking tax back out is the step that catches people, and it is a division rather than a subtraction. At 15%, 138 divided by 1.15 returns 120 exactly, whereas subtracting 15% from 138 gives 117.30 and understates the base by nearly three. That gap widens with the rate: subtracting 30% from a 130 total gives 91 when the true base is 100.
Common mistakes
- Subtracting the tax rate from the total to find the pre-tax price. At 15%, 138 minus 15% is 117.30, not 120, because the tax was charged on the smaller base.
- Applying the rate twice, or to a price that already includes tax, which turns a 15% tax into a 32% one and doubles the figure.
- Treating a rate you were quoted in one country as universal. A 20% VAT and a 5% sales tax are both real, and the tool simply applies whichever figure you type.
When to use it
- Use it for a receipt, an invoice or a quote where the price is stated before tax and you need the total, and for the reverse when you only have the tax-inclusive total and want the base.
- It is the wrong tool for an income-tax estimate, because earnings are taxed in bands rather than at one flat rate. For pay deductions use the take-home pay tool, which models each deduction as a share of gross.
Worked example
120 at 15% tax adds 18, for a total of 138.
Common questions
How do I remove tax from a total?
Divide by (1 + rate). Subtracting the percentage is wrong: at 30%, 130 ÷ 1.3 = 100, while subtracting gives 91.
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