How to Add or Remove VAT From a Price (Without the Common Mistake)
VAT and GST calculations come up constantly — on invoices, quotes, receipts and expense claims. Adding tax is easy; taking it out is where most mistakes happen.
Adding VAT to a net price
gross = net × (1 + rate). £100 + 20% VAT = £120. The VAT is £20.
Removing VAT from a gross price
net = gross ÷ (1 + rate). £120 ÷ 1.2 = £100. The VAT is £120 − £100 = £20.
The common mistake
Taking 20% off £120 gives £96 — wrong. The 20% was charged on £100, not on £120. So the VAT portion of a gross price is always a smaller share than the rate:
| Rate | VAT share of a gross price |
|---|---|
| 5% | 1/21 ≈ 4.76% |
| 10% | 1/11 ≈ 9.09% |
| 20% | 1/6 ≈ 16.67% |
| 21% | ≈ 17.36% |
Standard rates
The VAT / GST calculator includes standard rates for more than 40 countries, checked in October 2026 — all EU members, the UK, Switzerland, Norway, Australia, New Zealand, Canada (federal GST), India, Japan, South Korea, Taiwan and Latin America. Many countries also have reduced rates for food, books or transport; pick "Custom rate" and type the one you need.
Rounding
The calculator doesn't round intermediate steps. On invoices, rounding rules (per line or per invoice) are set by each country's tax authority — follow your accounting software.
For other percentage questions, use the percentage calculator.