Invoice Total Calculator
The calculator follows the standard invoice order of operations.
Enter Values
How to use this calculator
- Enter the subtotal — the total for goods or services before any discount or tax.
- Optionally add a discount percentage, a tax/VAT/GST rate, and any shipping or handling charge.
- Read the invoice total; open the working to see the discount, taxable amount and tax broken out line by line.
How it works
The calculator follows the standard invoice order of operations. First it takes the discount off the subtotal to get the taxable amount, then applies the tax rate to that discounted figure, and finally adds shipping on top. The formula is: total = (subtotal − subtotal × discount%) × (1 + tax%) + shipping.
Discounting before tax is the usual convention, because you are only taxed on what you actually pay for the goods. Shipping is added after tax here and is left untaxed, which matches many jurisdictions — but tax rules vary, so if your region taxes shipping, fold that charge into the subtotal instead so it is included in the taxable amount.
Worked example
Invoice with a 10% discount, 8% tax and shipping. A subtotal of 1,000 with a 10% early-payment discount, 8% sales tax and a 25 shipping charge. Discount = 1,000 × 10% = 100, so the taxable amount is 900. Tax = 900 × 8% = 72. Grand total = 900 + 72 + 25 = 997.
Common mistakes
- Applying the tax to the subtotal before the discount, which overstates the tax. Tax should be charged on the discounted (taxable) amount.
- Entering the discount as a currency amount instead of a percentage — this field expects a percent (e.g. 10 for 10% off).
- Assuming shipping is always tax-free. Some jurisdictions tax delivery charges; if yours does, add shipping into the subtotal so it is taxed.
Frequently asked questions
Is the discount taken before or after tax?
Before. The discount is subtracted from the subtotal first, and the tax is then charged on the reduced (taxable) amount. This is the standard convention and means you are not taxed on money you never paid.
Why isn't shipping taxed in this calculator?
Many jurisdictions treat separately-stated shipping as non-taxable, so the tool adds it after tax by default. Tax law varies by country and state — if delivery is taxable where you are, include the shipping charge in the subtotal so it becomes part of the taxable amount.
Can I use this for VAT or GST as well as sales tax?
Yes. The tax rate field is just a percentage, so enter your VAT, GST or sales-tax rate. Note that VAT/GST prices are often quoted tax-inclusive; if your subtotal already includes tax, use a GST or sales-tax calculator to back out the tax instead.
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