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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