About the Sales Tax Calculator
Add sales tax, VAT or GST to a price, or take it out of a price that already includes it. Enter the price and your tax rate, and see the tax, the total and the working, to the cent.
Tax rates differ by country, state, city and product, and they change, so the calculator never assumes a rate: you type the one that applies to you.
How it works
Adding tax to a price that doesn't include it: multiply the price by the rate to get the tax, then add it. Taking tax out of a price that already includes it is a little different: divide by 1 plus the rate. Subtracting the percentage from the total gives the wrong answer, because the tax was worked out on the smaller, pre-tax price.
The calculator uses exact decimal arithmetic and rounds once, to the cent, so the price and the tax always add up to the total.
Adding: tax = price × rate total = price + tax Removing: price = total ÷ (1 + rate) tax = total − price
Assumptions and limits
- One rate for the whole amount. Receipts with items taxed at different rates should be worked out per item.
- Rounding is half up to the cent. Some shops and tax authorities round per item or per invoice, which can change the last cent.
- Rates above 100% are refused, since they're almost always a typo.
Worked examples
A $49.99 purchase at 7.25%
Tax is 49.99 × 0.0725 = 3.624…, which rounds to $3.62, so the total is $53.61.
Taking 20% VAT out of £59.99
UK shop prices include VAT. 59.99 ÷ 1.20 = 49.99, so the price before VAT is £49.99 and the VAT is £10.00. Taking 20% off £59.99 would wrongly give £47.99.
Checking an invoice with 18% GST
An invoice shows ₹1,000 plus GST. 1,000 × 0.18 = ₹180 of tax, for a total of ₹1,180.
Adding versus removing the same rate
Removing tax from a total gives less tax than adding it to the same number, because the tax is a share of the smaller pre-tax price.
| Rate | Add tax to 100 | Remove tax from 100 |
|---|---|---|
| 5% | 105.00 | 95.24 (tax 4.76) |
| 7.25% | 107.25 | 93.24 (tax 6.76) |
| 10% | 110.00 | 90.91 (tax 9.09) |
| 18% | 118.00 | 84.75 (tax 15.25) |
| 20% | 120.00 | 83.33 (tax 16.67) |
How to use the Sales Tax Calculator
- Choose what your price is. Without tax (add it) or with tax already included (take it out).
- Enter the price and rate. Use the rate for your location and product.
- Read the result. Tax, total and working update as you type.
Frequently asked questions
How do I calculate sales tax?
Multiply the price by the rate written as a decimal, then add the result to the price. For $80 at 6%, the tax is 80 × 0.06 = $4.80 and the total is $84.80.
How do I work out the price before tax?
Divide the total by 1 plus the rate. For a $107 total at 7%, 107 ÷ 1.07 = $100, so the tax was $7. Subtracting 7% of $107 would give $99.51, which is wrong.
What tax rate should I use?
The one for where the sale happens and what is sold. US sales tax combines state, county and city rates; VAT and GST rates depend on the country and the product. Check your tax authority or a recent receipt.
Why is my answer a cent different from the receipt?
Shops may round the tax on each item and add the rounded amounts, while this calculator rounds once on the total. Both are legitimate methods, and the difference is usually a cent or two.
Does it work for VAT and GST?
Yes. VAT, GST and sales tax are all a percentage of the pre-tax price, so the same formulas apply. Choose 'Includes tax' for VAT-inclusive prices, which is how UK and EU shops display them.
This tool runs entirely in your browser. What you enter or upload stays on your device and is never sent to our servers.