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About this tool
Add or remove VAT/GST from an amount at any rate.
The VAT Calculator works in both directions at any rate: to add tax it computes VAT = net × rate ÷ 100 and gross = net + VAT, and to strip it out it divides back with net = gross ÷ (1 + rate ÷ 100), then reports VAT as the difference. Every result breaks out net, VAT and gross to two decimals alongside the tax fraction — rate ÷ (100 + rate) — which is the share of a tax-inclusive price the tax actually represents. It accepts any percentage, so the same box handles a 5%, 18% or 27% regime; the rate field simply starts at 18%.
Open VAT Calculator on AltFTool — it loads instantly in your browser.
Type the figure into the Amount field and set VAT / GST Rate (%), which open prefilled at 1000 and 18.
Choose Add VAT / GST or Remove VAT / GST in the Calculation dropdown — the Result panel recomputes as you type, with no calculate button.
Read the Net Amount, VAT Amount, Gross Amount, VAT Rate and Tax Fraction cards (15.25% of gross at an 18% rate), then press Copy to take the summary or Reset to restore the defaults.
Removing tax divides by (1 + rate ÷ 100) rather than subtracting the rate from the gross — the mistake that makes a 20% removal come out 4% short.
It prints rate ÷ (100 + rate) as a percentage of gross, so you can see that an 18% rate is 15.25% of an inclusive price and reuse that multiplier on other figures.
Nothing is hard-coded to one country's VAT or GST rate; type the percentage that applies, including fractional rates, and both directions recalculate.
Divide the gross amount by 1 plus the rate as a decimal — for an 18% rate, gross ÷ 1.18 — and the VAT is whatever is left over. Subtracting 18% from the gross is a different, smaller number and gives the wrong net.
Multiply the net by the rate divided by 100 to get the VAT, then add it to the net. On 1,000 at 18% that is 180 of VAT and a gross of 1,180.
It is rate ÷ (100 + rate), the proportion of a tax-inclusive price that is tax. At 20% it is exactly one sixth, or 16.67%; at 18% it is 15.25%. Multiplying a gross figure by that fraction extracts the tax in one step.
The same arithmetic applies to any single-rate tax expressed as a percentage of price, including GST. It does not model multi-slab structures, split CGST/SGST components, reverse-charge treatment or exemptions — for filing and compliance, check the figures with an accountant or your tax authority.
Add the VAT Calculator widget to your blog or website — free, responsive, no signup. Just keep the “Widget by AltFTool” credit link visible.
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