How to Calculate VAT: Formulas, Examples & Common Mistakes

Calculating VAT comes down to three situations: adding VAT to a net price, removing VAT from a gross price, and extracting just the VAT amount from a tax-inclusive figure. Each has one simple formula. This guide gives you all three, with worked examples you can copy, plus the mistakes that trip people up most often.

If you just need the answer fast, use the free VAT calculator on our homepage — it does all three calculations instantly for any country and currency. If you want to understand the maths (or check someone else's), read on.

Everything in VAT calculation is built from one relationship: Gross = Net × (1 + Rate). The rate is written as a decimal, so 20% becomes 0.20 and 1 + rate becomes 1.20.

1. Add VAT (net → gross): Gross = Net × (1 + Rate). Example: £100 net at 20% → £100 × 1.20 = £120 gross. The VAT itself is £100 × 0.20 = £20.

2. Remove VAT (gross → net): Net = Gross ÷ (1 + Rate). Example: £120 gross at 20% → £120 ÷ 1.20 = £100 net. The VAT portion is £120 − £100 = £20.

3. VAT only (gross → just the tax): VAT = Gross × Rate ÷ (1 + Rate). Example: £120 gross at 20% → £120 × 20 ÷ 120 = £20. Or from a net price: VAT = Net × Rate.

Use this when you have a price before tax — a wholesale price, your day rate, a supplier quote — and need the tax-inclusive total.

Step 1: convert the rate to a decimal. 20% → 0.20. Step 2: multiply the net price by the decimal to get the VAT amount. £250 × 0.20 = £50. Step 3: add it to the net price. £250 + £50 = £300.

Shortcut: multiply by (1 + rate) in one step. £250 × 1.20 = £300. Same answer, one less step.

Other common rates: at 15% (Bangladesh, Saudi Arabia) multiply by 1.15. At 5% (UAE) multiply by 1.05. At 10% (Australia GST) multiply by 1.10.

Use this when you have a tax-inclusive price — a receipt, a client payment, a retail price — and need to know the net amount and how much VAT was inside it.

Step 1: divide the gross price by (1 + rate). £300 ÷ 1.20 = £250 net. Step 2: subtract to get the VAT. £300 − £250 = £50.

The most common mistake here is taking a percentage of the gross instead. 20% of £300 is £60 — wrong. VAT was calculated on the net (£250), not the gross, so you must divide first, not multiply.

Quick check: the VAT fraction of a gross price is Rate ÷ (1 + Rate). At 20% that's 20/120 = 1/6. So one-sixth of any 20%-inclusive price is VAT. £300 ÷ 6 = £50. At 15% the fraction is 15/115 ≈ 13.04%. At 5% it's 5/105 ≈ 4.76%.

Sometimes you only need the tax figure — for a VAT return line, an expense claim, or to show a customer 'of which VAT'.

From a net price: VAT = Net × Rate. £1,000 × 0.20 = £200.

From a gross price: VAT = Gross − (Gross ÷ (1 + Rate)). £1,200 − (£1,200 ÷ 1.20) = £1,200 − £1,000 = £200.

UK, 20%: £500 net → £100 VAT → £600 gross. Reverse: £600 gross → £500 net, £100 VAT.

Germany, 19%: €500 net → €95 VAT → €595 gross. Reverse: €595 ÷ 1.19 = €500 net.

Bangladesh, 15%: Tk 10,000 net → Tk 1,500 VAT → Tk 11,500 gross. Reverse: Tk 11,500 ÷ 1.15 = Tk 10,000 net.

UAE, 5%: AED 2,000 net → AED 100 VAT → AED 2,100 gross. Reverse: AED 2,100 ÷ 1.05 = AED 2,000 net.

Australia, 10% GST: A$1,100 gross → A$1,100 ÷ 1.10 = A$1,000 net, A$100 GST.

Taking a percentage of the gross to 'remove' VAT. Always divide by (1 + rate) first — the VAT was calculated on the net, not the gross.

Using the wrong rate. Many countries have reduced rates for specific goods (food, books, energy). Check the rate for your specific product, not just the headline standard rate.

Mixing up net and gross on invoices. If you quote a client a net price but they expected gross (or vice versa), someone ends up 20% out of pocket. Always state which one your price is.

Rounding too early. Calculate with full precision and round only the final figures to two decimals — rounding mid-calculation can drift totals on multi-line invoices.

The calculator on our homepage does all of this for you: pick a country, enter an amount, and choose Add VAT, Remove VAT, or VAT only. It handles 49 countries with their current standard rates.

Working with Bangladesh specifically? Our Bangladesh calculator is sector-aware — it handles the different rates for restaurants, construction, IT services and more, not just the 15% standard rate.

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