# Invoice calculator

> Add your line items to get the subtotal, tax and total, then turn them into an invoice.

Canonical: https://www.invoqk.com/invoice-calculator

Total = sum of quantity × price, plus tax on each line.

## How to calculate an invoice

An invoice total is the sum of every line, quantity times unit price, plus tax. Showing the subtotal and tax separately makes the invoice easy for the client to check.

Rounding to two decimals per invoice keeps the total consistent with what you report in your books.

## Common questions

### How do you calculate an invoice total?

Multiply quantity by unit price for each line, add the lines for the subtotal, then add tax.

### How is tax added to an invoice?

Multiply each line by its tax rate and add it, or apply one rate to the subtotal if all lines share it.

### Can lines have different tax rates?

Yes. Set the rate on each line and the tax is added per line.

### Can I create the invoice from these numbers?

Yes. Use the button to start an invoice, or describe the lines in text and let the generator build it.

## Related

- [Free invoice calculators](https://www.invoqk.com/calculators)
- [Invoqk home](https://www.invoqk.com)