VAT / GST Calculator

VAT / GST Calculator — guide & how to use

What it does

This calculator works in both directions. Choose Add VAT/GST when your amount is the net (pre-tax) price and you want the tax added on top to get the gross. Choose Remove VAT/GST when your amount is the gross (tax-inclusive) total and you want to back the tax out to find the net. Either way it shows all three figures — net, VAT/GST amount, and gross — at any rate, with country presets to fill the rate for you. Everything runs privately in your browser, free.

How to use it

1. Pick a direction: Add VAT (amount is net → tax added) or Remove VAT (amount is gross → tax backed out).
2. Enter the amount. Its meaning follows the direction — the label updates so you always know whether you're entering net or gross.
3. Set the rate, or pick a country preset to fill it (UK 20%, Germany 19%, Australia 10% GST…). Override it for reduced or zero-rated items.
4. Read the headline (gross when adding, net when removing) plus the full net / VAT / gross breakdown.

Worked example

Adding VAT: a net price of £100 at the UK standard rate of 20%.

1. r = 20 / 100 = 0.20.
2. VAT = 100 × 0.20 = £20.00.
3. Gross = 100 × 1.20 = £120.00 ← the headline.

Removing VAT: a tax-inclusive total of £120 at 20%.

1. Net = 120 / 1.20 = £100.00 ← the headline. (Note: not 120 − 20% = £96 — that's the classic mistake.)
2. VAT = 120 − 100 = £20.00, which is 16.67% of the gross but 20% of the net.

The formula

r = rate% / 100              (20% -> 0.20)

ADD VAT  (amount = NET):
  net   = amount
  vat   = amount × r
  gross = amount × (1 + r)    (= net + vat)

REMOVE VAT  (amount = GROSS):
  net   = amount / (1 + r)
  vat   = amount − net        (= amount × r / (1 + r))
  gross = amount

vat is always gross − net. Add -> multiply by (1 + r);
remove -> divide by (1 + r). Never divide by the rate itself.

Rounding: figures are computed at full precision, then each displayed value is rounded to 2 decimals half-up (≥ half a penny rounds up, the HMRC rule). The third figure is reconciled by subtraction so net + VAT always equals gross to the penny.

Accuracy & disclaimers

• This is an arithmetic tool, not tax advice. It does the math only; it does not determine whether VAT/GST actually applies to a sale, the correct rate band, place-of-supply, reverse-charge, or registration thresholds.
• Standard rates change. Built-in country presets reflect standard rates current as of early 2026 — verify before filing. The manual rate field is authoritative and overrides any preset.
• Many goods use reduced, zero or exempt rates (food, books, children's items, exports). The preset is the standard rate only — enter the correct band for your item. "Exempt" and "zero-rated" differ in law but both produce 0 VAT here; the tool only does arithmetic.
• Rounding can cause penny differences between summing line items and totalling an invoice. Authorities accept any fair, consistent method; this tool rounds the displayed total half-up. Accounting software that rounds per line may differ by a penny.
• US sales tax is NOT VAT/GST and is calculated differently (no inclusive back-out, varies by state/locality). Use a sales tax calculator for the US. 100% client-side — nothing leaves your device.

Common mistakes this tool prevents

• Removing VAT by taking the percentage off the gross (gross × 0.8) instead of dividing by 1.20. At 20%, 120 × 0.8 = 96 is wrong; the correct net is 120 / 1.20 = 100. This is the single most common VAT error.
• Thinking the VAT inside a tax-inclusive price equals the headline rate. In £120 gross at 20%, the VAT is £20 — 16.67% of the gross, not 20% of it.
• Mislabelling net vs gross, so you compute the wrong direction. The amount label updates with the direction toggle to keep them straight.
• Entering the rate as a decimal (0.2) when the field expects a percent (20), giving a 0.2% calculation.
• Rounding intermediate values then summing, instead of rounding once for display — the tool reconciles by subtraction so the three figures always add up.
• Assuming the country preset's standard rate applies to every item, when the item is actually reduced or zero-rated.

How to embed this tool on your website

No account, no coding. Copy the embed code and paste it where you want it to appear:

<!-- height starts at 980px; raise it if the tool looks clipped on your page -->
<iframe src="https://snaptoolsuite.com/vat-gst-calculator/?embed=1"
  style="width:100%;max-width:560px;height:980px;border:0;"
  title="VAT / GST Calculator" loading="lazy"></iframe>
<p>Free <a href="https://snaptoolsuite.com/vat-gst-calculator/">VAT / GST Calculator</a> by Snap Tool Suite</p>

See it live: view a real embed example →

Frequently asked questions

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