Sales Tax & GST Calculator 🧾 — Reverse Tax Calculator
Add or remove GST, VAT, and sales tax from any amount. Reverse tax calculator finds the pre-tax price from any tax-inclusive total. Supports US states, India GST, UK VAT, EU, Australia, and Canada.
Free Sales Tax Calculator — Reverse Tax Calculator for GST, VAT & US Sales Tax
Our free sales tax calculator and reverse tax calculator handles both directions of tax calculation in one tool — add tax to a pre-tax price (tax exclusive), or use the reverse sales tax calculator to remove tax from a total and find the original pre-tax amount (tax inclusive). Supports US state sales tax rates, India GST slabs, UK VAT, EU VAT by country, Australia GST, and Canada GST/HST — plus a custom rate for any country or situation. The multi-rate comparison table shows what the same amount costs at different tax rates simultaneously.
What Is a Reverse Tax Calculator?
A reverse tax calculator (also called a tax reverse calculator, backwards tax calculator, or tax-back calculator) answers the question: "I paid $X total — how much of that was tax?" Instead of adding tax to a price, it works backwards from the tax-inclusive total to find the pre-tax amount. Reverse tax formula: Pre-tax Amount = Total ÷ (1 + Tax Rate%). Tax Amount = Total − Pre-tax Amount. Example: You paid $118 for a product with 18% GST included. Pre-tax = $118 ÷ 1.18 = $100. GST = $118 − $100 = $18. This is essential for accountants processing receipts, businesses claiming input tax credits, and individuals understanding their actual spending versus tax paid.
Tax Exclusive vs Tax Inclusive — Key Difference
Tax Exclusive (Add Tax): The listed price does not include tax. Tax is added at checkout. Common in US retail, B2B invoicing worldwide, and most professional service quotes. Formula: Gross = Net × (1 + Rate%). $500 + 10% GST = $550. Tax Inclusive (Remove Tax / Reverse): The listed price already includes the tax. Common in UK and EU retail, Australian grocery and retail pricing, and restaurant prices in most countries. Formula: Net = Gross ÷ (1 + Rate%). Tax = Gross − Net. $550 inclusive of 10% GST: Net = $550 ÷ 1.10 = $500, Tax = $50.
US Sales Tax by State 2026 — What Rate to Use
US sales tax has no federal standard — each state sets its own rate, and most states also allow county and city taxes on top. Five states have no state sales tax: Oregon, Montana, New Hampshire, Delaware, and Alaska (though Alaska allows local taxes). The highest combined rates in 2026 are Louisiana (~9.55%), Tennessee (~9.55%), and Arkansas (~9.47%). The most common rates for the largest states: California 7.25% (state only; combined up to 10.75%), Texas 6.25%, New York 4% state (up to 8.875% with NYC), Florida 6%, Pennsylvania 6%, Illinois 6.25%. Always use your specific city/county combined rate for accurate pricing — state rates alone often underestimate the total tax charged.
India GST Calculator — 5%, 12%, 18%, 28% Slabs
India's GST has four main rate slabs. 5% — essential goods: packaged food, transport, household items. 12% — processed food, mobile phones, business class air tickets. 18% — the most common rate for manufactured goods, electronics, IT services, restaurant dining. 28% — luxury goods, tobacco, aerated drinks, high-end cars, cement. For B2B invoicing within a state, GST splits as 50% CGST + 50% SGST. For inter-state transactions, it becomes IGST at the full rate. This calculator computes the total GST and works in both exclusive and inclusive (reverse) mode for all four slabs.
UK VAT Reverse Calculator — 20%, 5%, 0%
UK VAT has three rates. Standard rate (20%) applies to most goods and services. Reduced rate (5%) applies to domestic fuel and power, children's car seats, mobility aids, and some renovation work. Zero rate (0%) applies to most food, books, newspapers, children's clothing, and public transport. Because UK retail prices are always displayed inclusive of VAT, the reverse VAT calculator is particularly useful — to find the VAT in a UK price, multiply by 20 and divide by 120 (at standard rate): £120 inclusive price × 20 ÷ 120 = £20 VAT. The pre-VAT price is £100.
What Makes This Calculator Different?
Most free tax calculators have two buttons (add/remove) and show 3 numbers. This tool adds: region presets (US states, India GST, UK VAT, EU, Australia, Canada) with quick rate buttons, a formula display showing the exact calculation method, secondary stats (tax as % of total, tax per $100, multiplier), a multi-rate comparison table showing the same amount at all rates in the selected region simultaneously, and a copy results button. All calculations run instantly in the browser.
Frequently Asked Questions
What is a reverse tax calculator and how does it work?
Finds pre-tax amount from a tax-inclusive total. Formula: Pre-tax = Total ÷ (1 + Rate%). Tax = Total − Pre-tax. Example: $118 total at 18% GST → $118 ÷ 1.18 = $100 pre-tax, $18 tax. Use the "Remove Tax" button above.
What is the sales tax rate in the US by state in 2026?
Ranges from 0% (Oregon, Montana, NH, Delaware) to 7.25% state (California). Combined city+state highest: Louisiana ~9.55%, Tennessee ~9.55%. Select "US States" above to load common state rates.
What is the difference between tax exclusive and tax inclusive pricing?
Tax exclusive: price shown without tax, tax added at checkout (US retail, B2B invoices). Tax inclusive: price already includes tax (UK/EU/Australian retail, restaurant menus). Use "Add Tax" for exclusive, "Remove Tax" for inclusive.
What is GST in India and what are the GST slab rates?
India GST slabs: 0% (essentials), 5% (basic goods), 12% (processed food, phones), 18% (most goods/services — most common), 28% (luxury/tobacco). Select "India GST" above for quick slab buttons.
What is VAT and how is it calculated in the UK?
UK VAT: 20% standard, 5% reduced (fuel, car seats), 0% (food, books). Prices in UK are VAT-inclusive. Reverse VAT: £120 ÷ 1.20 = £100 pre-VAT, £20 VAT. Select "UK VAT" above for quick buttons.
How do I calculate GST on an invoice in Australia?
Australia GST = 10%. To add: × 1.10. To find GST in inclusive price: ÷ 11. $550 ÷ 11 = $50 GST, $500 pre-GST. Businesses must register for GST if turnover exceeds AUD $75,000.
About This Tool
This Sales Tax and Reverse Tax Calculator was built by the FreeImageTools team — accountants, freelancers, and e-commerce sellers who calculate tax amounts daily for invoices, receipts, and expense claims. The original tool had 2 buttons and 3 numbers. We rebuilt it with regional presets (US states, India GST, UK VAT, EU, Australia, Canada), quick rate buttons per region, a formula display, secondary stats (tax as % of total, per-$100 tax, multiplier), a multi-rate comparison table, and a copy results button. All formulas are mathematically verified. Reviewed in July 2026.