Tax math shouldn't require a calculator. Oh wait, it should.
You're selling something for $100. GST is 10%. Is the price $110 including tax, or is $100 including tax? If it's $100 including tax, your net is $90.91. If it's $100 before tax, the customer pays $110. Get this wrong and you're either shortchanging yourself or overcharging customers. This calculator removes the confusion and handles GST/VAT instantly.
What This Calculator Does
This tool calculates GST or VAT in both directions. You can calculate the tax amount on a pre-tax price, or you can remove the tax from an inclusive price to find the net. It handles any tax rate (10% GST in Australia, 20% VAT in the UK, 13% HST in Canada). Feed in your price and tax rate, and the calculator shows the tax amount, total with tax, and the pre-tax amount.
How to Use This Calculator
Step 1: Decide whether you're working with a price before tax or after tax. If you're starting with a supplier invoice ($100), you're working with the pre-tax amount. If you're looking at a customer's receipt ($110 total), you're working with the tax-inclusive amount.
Step 2: Enter your tax rate. This varies by country: Australia uses 10% GST, Canada uses 5-15% HST depending on province, the UK uses 20% VAT (with some exceptions), the US uses 0-10% state sales tax, New Zealand uses 15% GST. Know your jurisdiction.
Step 3: If calculating tax on a pre-tax amount: enter the price and the calculator adds tax. If calculating tax on an inclusive amount: enter the total and the calculator removes tax to show the net.
Step 4: The calculator shows tax amount, pre-tax amount, and total with tax. Use this for pricing, invoicing, or accounting reconciliation.
Step 5: For repeat calculations, save the tax rate in your calculator so you don't have to re-enter it every time.
The Formula Behind the Math
Adding Tax to a Pre-Tax Amount
Tax Amount = Pre-Tax Price × (Tax Rate / 100)
Total with Tax = Pre-Tax Price + Tax Amount
Or more simply: Total = Pre-Tax Price × (1 + Tax Rate / 100)
Example (10% GST):
Pre-tax price: $100
Tax amount: $100 × 0.10 = $10
Total: $100 + $10 = $110
Or: $100 × 1.10 = $110
Removing Tax from a Tax-Inclusive Amount
Tax Rate as Multiplier = (100 + Tax Rate) / 100
Pre-Tax Price = Tax-Inclusive Price / Tax Rate Multiplier
Tax Amount = Tax-Inclusive Price - Pre-Tax Price
Example (10% GST, working backwards):
Tax-inclusive price: $110
Tax rate multiplier: 110 / 100 = 1.10
Pre-tax price: $110 / 1.10 = $100
Tax amount: $110 - $100 = $10
Verifying calculations:
Pre-tax + Tax = Tax-inclusive
$100 + $10 = $110 ✓
Our calculator does all of this instantly-but now you understand exactly what it's computing.
E-commerce Business Pricing Products
You're selling globally. Your product costs $20 to make (COGS). You want 60% gross margin. Your pricing is $50 ex-tax (before tax). A customer in Australia buys it (10% GST): they pay $55. A customer in the UK buys it (20% VAT): they pay $60. A customer in Canada buys it (13% HST): they pay $56.50. Your margin on each sale is still 60% on the pre-tax price. This calculator helps you quote prices to different regions correctly.
Accounting Reconciliation
You received an invoice from a supplier: $1,000 ex-GST (Australia). The invoice shows 10% GST = $100 tax, total = $1,100. You need to check if the math is right. Enter 1,000 and 10%, and the calculator confirms: tax is $100, total is $1,100. Correct. Without this calculator, you'd pull out a physical calculator and risk errors.
Freelancer Invoicing
You're a freelancer in the UK (20% VAT). A client asks: "What's your rate?" You charge £80 per hour ex-VAT. If they ask for the total with tax, it's £96 per hour (£80 × 1.20). If they ask for the pre-VAT rate and you're charging £96 all-in, the actual rate is £80 and the client owes £16 in VAT. Know the difference so you invoice correctly.
Retail Business Calculating Prices
You're a retailer in a state with 8.5% sales tax. Your supplier sells you a shirt for $10 wholesale. You want 100% markup (double the cost). Your retail price before tax is $20. The customer pays $20 × 1.085 = $21.70. Your actual profit (before other costs) is $10 per shirt. This calculator helps you think through pre-tax and post-tax pricing so you can properly mark items for sale.
Tips and Things to Watch Out For
Know your local tax rules. Some countries tax services differently from products. Some products are exempt (books, medical items in some countries). Digital products might be taxed differently from physical products. Know the rules in your jurisdiction so you charge the right amount.
Tax-inclusive vs. tax-exclusive pricing. Most of the world uses tax-inclusive pricing (the price shown includes tax). The US primarily uses tax-exclusive (tax is added at checkout). Australia, UK, EU use tax-inclusive. Make sure you know which model applies to you.
Export sales might have different rules. If you're selling to a customer in another country, different tax rules might apply. Some countries zero-rate exports (no tax on goods leaving the country). Others don't. Research before quoting international customers.
VAT is charged on supplies, not products. VAT is a value-added tax, so it's charged on the economic supply, not the physical product. This matters for digital goods, services, and goods crossing borders. Understand whether your supply is subject to VAT where you're selling.
B2B vs. B2C rules differ. If you're selling to a business (B2B), the business might be VAT-registered and entitled to recover VAT. If you're selling to a consumer (B2C), they pay VAT and can't recover it. Invoice format and tax treatment differ. Know who you're selling to.
Keep records for tax time. Save all invoices with tax amounts. Your accountant will need them at year-end. Most countries require you to track and remit collected tax quarterly or annually. This calculator helps you organize, but keep source documents.
Multi-currency and multi-country complexity. If you're selling internationally, you might need to charge tax in each country where your customer is located. VAT ID validation, reverse-charge mechanisms, and other rules apply. Consider an international tax compliance tool for complexity.
*This GST/VAT calculator computes tax based on the rate you input. Tax laws are complex and vary by jurisdiction, product type, customer type, and supply type. This calculator is for estimation and educational purposes. For accurate tax calculations on your business, consult a tax professional or accountant in your jurisdiction.*
Frequently Asked Questions
What's the difference between GST and VAT?
GST (Goods and Services Tax) and VAT (Value-Added Tax) are essentially the same thing-a consumption tax applied at each stage of production. Australia, Canada, and New Zealand call it GST. EU, UK, and most other countries call it VAT. The mechanics are identical; only the rate and exact rules differ by country.
Should I show prices with or without tax on my website?
Depends on your jurisdiction and customer base. In Australia and UK (B2C), show prices with tax included. In the US, show prices without tax (tax is added at checkout). In EU B2B, show prices without tax (with note that it's ex-VAT). Follow local custom so customers don't get surprised at checkout.
How do I know my tax rate?
For Australia, it's 10%. For Canada, it varies by province (5-15%). For UK, it's 20% (with reduced rates for some items like books and food). For the US, check your state and local tax rate. For EU countries, check the HMRC or VIES (VAT Information Exchange System) websites for your specific country.
What if I'm tax-exempt?
Some businesses are exempted from collecting or paying tax (non-profits, government agencies, some religions). If you're exempt, apply for exemption with your tax authority and get a certificate. Customers will provide you their exemption certificate when ordering. Don't charge tax to exempt customers.
How do I handle taxes if I sell across borders?
This is complex. Generally: B2B sales (business-to-business) are reverse-charged (buyer pays tax in their country). B2C sales (business-to-consumer) are charged in the seller's country. For EU sales, new rules (OSS) apply if you cross-sell multiple countries. Consult a tax professional for international selling.
Should I include tax in my wholesale pricing?
No. Wholesale is typically quoted ex-tax (before tax). The wholesaler remits tax when resold. Quote your wholesale price without tax, and the retailer adds tax when selling to end customers. This prevents double taxation.
What if I make a mistake on an invoice?
Issue a credit note (negative invoice) for the incorrect amount, then issue a corrected invoice. Don't try to fix the original; this creates audit trail issues. Most invoicing software handles this with a "refund" or "credit" function.
How do I track tax for quarterly or annual remittance?
Use accounting software (QuickBooks, Xero, Wave) that tracks tax automatically. Manually, keep a running total of tax collected each month, and remit to your tax authority according to their schedule (usually quarterly or annually). The calculator helps you get the math right; the accounting system helps you track the total.
Related Calculators
Use the invoice calculator to include tax amounts on customer invoices. Check the pricing calculator to ensure your product prices are set correctly before adding tax. The discount calculator helps you apply discounts and then calculate tax on the discounted amount.