Invoice Calculator

How to calculate an invoice total

1. Add each line-item amount (quantity × rate).
2. Apply any percentage or fixed discount.
3. Add applicable tax on the discounted subtotal.
4. Add shipping or other fees.
5. Subtract payments already received to determine the balance due.

For a full walkthrough of building and sending invoices, see Creating Invoices. Payment timing is covered in invoice payment terms, and deposits are explained in invoice deposits.

Invoice calculator formula

Invoice total = subtotal − discounts + tax + shipping + fees

Balance due = invoice total − payments already received

Tax is calculated after the discount: tax = (subtotal − discounts) × tax rate. To focus on discount math alone, use the Invoice Discount Calculator.

Frequently asked questions

What is an invoice calculator?

An invoice calculator adds line items and adjustments so you can see the invoice total and the balance still due. Use it to check pricing before you create or send an invoice.

How do I calculate the total amount of an invoice?

Add each line-item amount, subtract any discount, add tax, then add shipping or other fees. The result is the invoice total. Subtract payments already received to get the balance due.

Is tax calculated before or after a discount?

This calculator applies tax after the discount, on the discounted subtotal. Tax treatment can depend on your jurisdiction, so confirm the rules that apply to your invoices before you bill a customer.

Can I calculate an invoice with multiple line items?

Yes. Add as many line items as you need. Each amount is quantity × rate, and the calculator sums them into the subtotal.

What is the difference between invoice total and balance due?

Invoice total is the full amount of the invoice after discounts, tax, shipping, and fees. Balance due is what remains after subtracting deposits or other payments already received.