Invoice Calculator

Calculate invoice totals including line items, discounts and tax. Add your items, choose a discount and tax rate to get the subtotal, discount, tax and final total.

Add a row for each line item with its price and quantity. Then choose a discount (percentage or fixed amount) and a tax rate. The calculator returns the subtotal, discount amount, tax amount and final invoice total.

PriceQty
Percentage or amount depending on the type above
Subtotal —
Discount amount —
Tax amount —
Invoice total —

An invoice calculator totals a list of line items, applies a discount (as a percentage or fixed amount), then adds tax to reach the final amount due — ideal for quick quotes and billing checks.

The maths

  • Subtotal = sum of (price × quantity) for every line
  • Discount = subtotal × discount% (or the fixed amount), capped at the subtotal
  • Tax = (subtotal − discount) × tax%
  • Total = subtotal − discount + tax

Examples

  • Two items at $50 × 2 = $200 subtotal
  • 10% discount = $20 off, leaving $180
  • 20% tax on $180 = $36, total = $216

Frequently asked questions

Is tax applied before or after the discount?

After. Tax is calculated on the discounted subtotal, which is the usual convention for net-of-discount invoicing.

Can the discount exceed the subtotal?

No — a fixed-amount discount is capped at the subtotal so the discounted amount never goes negative.

Just for the giggles, much love.
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