GST / VAT Calculator
Add a tax to a net amount or back-calculate the net from a gross. 18 region presets (UK, EU, India GST 5/12/18/28, Australia, NZ, Canada GST/HST/QST, Singapore, South Africa, Japan), 23 currencies and switchable mode. Free and private.
What is the GST / VAT Calculator?
A GST / VAT calculator adds a percentage tax to a net amount (gross = net × (1 + r)) or reverses the operation to back-calculate the pre-tax value from a gross price (net = gross ÷ (1 + r)). Toollyz GST / VAT Calculator does both in one tabbed UI and ships with 18 region presets — UK (20% / 5% reduced), Germany (19%), France (20%), Italy (22%), Spain (21%), India GST at 5 / 12 / 18 / 28%, Australia GST 10%, New Zealand GST 15%, Canada federal GST 5%, Canada Ontario HST 13%, Canada Quebec QST + GST 14.975%, Singapore GST 9%, South Africa VAT 15% and Japan consumption tax 10%. Pick a preset and both the tax rate and the display currency snap to that country's convention; tweak either freely afterwards. The hero shows net (pre-tax), tax amount and gross (incl. tax) in three live cards with the gross / net cells emphasised based on the active mode. A Switch-mode button flips the calculator and carries the result across so you can verify both directions of the math. Toollyz has no backend; the last amount, rate, region and currency save to localStorage on this device only.
How to use it
- Pick the mode: Add tax (net → gross) or Remove tax (gross → net).
- Type the amount, pick a region preset (or set a custom rate), and pick a display currency.
- Read net / tax / gross live in the hero — the highlighted cards depend on the active mode.
- Click Switch mode to verify the math by feeding the result back the other way.
Benefits
- Two modes — Add tax and Remove tax — in a single tabbed UI.
- 18 region presets covering UK, EU (DE/FR/IT/ES), India GST tiers, Australia, NZ, Canada GST / HST / QST+GST, Singapore, South Africa, Japan.
- Each preset snaps both the tax rate and the display currency to the country's convention.
- 23 ISO 4217 currencies via `Intl.NumberFormat` with proper symbols and decimals.
- Quick-rate chips for 5 / 10 / 12 / 15 / 18 / 20 / 22 / 25%.
- Switch mode flips the calculator and carries the result across to verify both directions.
- Copy-summary action for sharing in chat or email.
- 100% private — Toollyz has no backend, the form saves to localStorage on this device only.
Frequently asked questions
What's the difference between Add tax and Remove tax?
Add tax treats the entered amount as the net (pre-tax) price and adds the tax: gross = net × (1 + r). Remove tax treats the entered amount as the gross (tax-inclusive) price and back-calculates the net: net = gross ÷ (1 + r). The tax amount is the difference in either direction.
Why net = gross ÷ (1 + r) rather than gross − (gross × r)?
Because the tax is computed on the net, not the gross. If gross = net + net × r = net × (1 + r), then net = gross ÷ (1 + r). Subtracting gross × r would over-deduct the tax — a common spreadsheet bug. Toollyz uses the correct formula.
Which regions are included?
United Kingdom (20% standard, 5% reduced), Germany (19%), France (20%), Italy (22%), Spain (21%), India GST at 5%, 12%, 18% and 28%, Australia (10% GST), New Zealand (15% GST), Canada federal GST (5%), Canada Ontario HST (13%), Canada Quebec QST + GST combined (14.975%), Singapore (9% GST), South Africa (15% VAT) and Japan (10% consumption tax). For other regions, pick "Custom rate" and type the percentage.
Do the rates stay up to date automatically?
No — these are static defaults as of mid-2026. Tax rates change occasionally (UK reduced 5%, NZ raised to 15% in 2010, etc.); Toollyz doesn't auto-update. If a country changes its rate, just type the new percentage into the Tax rate field.
Can I model Canadian PST + GST?
The QST + GST preset (14.975%) is included for Quebec. Other provinces with PST (BC 7%, Saskatchewan 6%, Manitoba 7%) are not pre-loaded; either pick Canada federal GST 5% and add your PST manually, or set a custom rate to model both at once.
How precise is the calculation?
Math runs in IEEE 754 double precision — accurate to about 15 significant digits, well beyond any sales-tax need. Output rounds to two decimal places (or zero for zero-decimal currencies like JPY).
Why does the currency change when I pick a region?
Each region preset includes the country's usual currency (UK → GBP, India → INR, Australia → AUD, etc.) so the displayed amount matches local convention. You can change the currency manually after picking a preset.
Is there an itemised mode for multi-line invoices?
Not in this tool — for invoices with multiple line items and per-item taxes, use the Toollyz Invoice Generator. The GST / VAT Calculator is for single-amount conversions.
Are my inputs uploaded?
No. Toollyz has no backend — the math runs in your browser. Your last amount, rate, region and currency save to localStorage on this device only.
Is this GST / VAT Calculator free?
Completely free with no signup and no limits. Compute as many tax conversions as you like — privately in your browser.