Invoice Calculator

Total up an invoice: up to three line items (quantity × unit price), a discount, and sales tax or VAT on the discounted subtotal.

$
$
Leave at 0 if unused.
$
%
Applied to the subtotal before tax.
%
Applied to the discounted subtotal. Assumes every line is taxable at this rate.
Your rate is remembered on this device.
Invoice total
$437.40
Line 1 amount
$250.00
Line 2 amount
$200.00
Line 3 amount
$0.00
Subtotal
$450.00
Discount
-$45.00
Subtotal after discount
$405.00
Tax
$32.40

Estimate generated with SortedSums: https://sortedsums.com/invoice-calculator/. For informational purposes only; verify before relying on it.

Estimate only. This tool is for informational and educational purposes. Results depend on your inputs and simplifying assumptions, and are not a substitute for professional engineering, design or financial advice. Always verify with a qualified professional and applicable codes before purchasing, building or making decisions.

How it’s calculated

Each line is quantity × unit price. The discount comes off the subtotal, and tax is charged on the discounted amount.

Subtotal = Σ (quantity × unit price) Discounted subtotal = Subtotal × (1 − discount%) Tax = Discounted subtotal × tax% Total = Discounted subtotal + Tax

Example: 10 × 25 = 250 and 2 × 100 = 200 give a subtotal of 450. A 10% discount (45) leaves 405, 8% tax adds 32.40, and the invoice total is 437.40.

This is general arithmetic. Tax rules (which items are taxable, rounding per line, what an invoice must show) depend on your jurisdiction.

Frequently asked questions

Is tax calculated before or after a discount?

Usually after: a discount given at the time of sale reduces the taxable amount. Some coupons and manufacturer rebates are treated differently, so check local rules.

Should I round tax on each line or on the total?

This calculator taxes the total. Rounding per line can differ by a cent or two; follow your tax authority’s or accounting software’s rule.

What must an invoice include?

Typically your business name and details, the customer, an invoice number and date, a description of each item, amounts, any tax shown separately and the total due. VAT invoices have specific required fields.

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Sources

Formulas are taken from the free public references above. Results are provided “as is” for informational and educational purposes only. See our disclaimer.

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