Invoice Calculator
Invoice totals from line items, with a discount, the tax rate you enter and payments already received.
Your invoice
Filled in with example values. Replace them with your own.
- $750.00
- $120.00
- $46.50
Totals
Taken off the subtotal before tax.
Currency symbol
Results update as you type.
Result
Design work (hours): 10 × $75.00 = $750.00
Invoice total
$916.50
- Subtotal
- $916.50
- Total
- $916.50
How it’s calculated
Subtotal
$750.00 + $120.00 + $46.50 = $916.50
Total
subtotal = $916.50
How the invoice calculator works
Each line is the quantity times the unit price. The lines add up to the subtotal; a discount, if any, comes off next; then tax is added at the rate you enter. If the client has already paid a deposit or part of the invoice, it is taken off the total to give the amount due.
All amounts are calculated in whole cents, so every figure adds up exactly.
The formula
Line = Quantity × Unit price
Subtotal = Sum of lines
Tax = (Subtotal − Discount) × Tax rate %
Total = Subtotal − Discount + Tax
Amount due = Total − Already paid
Worked example
An invoice has three lines: 10 hours of design at 75, a hosting setup at 120 and 3 stock photos at 15.50. The client gets 10% off, the tax rate is 20%, and a 200 deposit has been paid.
- Lines: 750 + 120 + 46.50 = 916.50
- Discount: 916.50 × 10% = 91.65, leaving 824.85
- Tax: 824.85 × 20% = 164.97
- Total: 824.85 + 164.97 = 989.82
- Amount due after the deposit: 789.82
Assumptions and limitations
- One tax rate applies to the whole invoice. Invoices mixing taxed and untaxed items need separate calculations.
- The calculator does not check whether tax should be charged; that depends on your registration and the customer.
- Nothing you enter is saved or sent anywhere.
Frequently asked questions
Which tax rate should I use?
It depends on where you and your customer are, what you sell, and whether you are registered for VAT, GST or sales tax. The calculator does not assume a rate; enter the one that applies to this invoice, or leave it empty if none does.
Is the discount taken before or after tax?
Before. The discount reduces the subtotal, and tax is worked out on the discounted amount, which is the usual way to discount an invoice.
How are amounts rounded?
Each line is rounded to the cent, then the discount and tax are each rounded to the cent. The total is the sum of the rounded figures, so the numbers on the invoice always add up.
Can I use it for hours?
Yes. Put the hours in the quantity column and your hourly rate as the unit price. Fractions such as 2.5 hours work.
Does this create an invoice document?
No, it works out the figures. Use “Copy result” to paste the lines and totals into your invoice or accounting software.