Total up an invoice in seconds. Enter the subtotal, a tax rate, and any discount, and see the tax, discount, and final total to bill.
Applies the discount to the subtotal first, then tax on the discounted amount (the common method). Your local tax rules may differ.
Subtract any discount from the subtotal, add tax on the discounted amount, and that's the total to bill. A $1,000 subtotal with an 8% tax and no discount comes to $1,080.
Total = (subtotal − discount) × (1 + tax rate)
An invoice total looks like addition and is really a sequence. Take the subtotal, subtract any discount, then apply tax to the discounted amount: total = (subtotal − discount) × (1 + tax rate). Doing the two steps in the other order changes the money. That is the entire reason this page exists — the arithmetic is easy, the sequence is what people get wrong, and the difference shows up as a mismatch between what you billed and what your bookkeeping expects.
The defaults are a $1,000 subtotal, an 8% tax rate and a 0% discount. Discount is $0, tax is $1,000 × 0.08 = $80, and the total to bill is $1,000 + $80 = $1,080.
Now add a 10% discount, which is where the sequence bites. Discount first: $1,000 × 0.10 = $100, leaving $900. Tax on $900 is $900 × 0.08 = $72. Total = $900 + $72 = $972. Do it the wrong way — tax the full $1,000 to get $1,080, then take $100 off — and you bill $980. The $8 gap is the tax you charged on a discount you gave away, and in most sales-tax regimes it is tax you are not entitled to collect, because tax is due on the price actually paid.
Discount-then-tax is the common treatment for a seller's own discount, and it is what this calculator does. Be aware of two honest limits. First, tax rules genuinely vary by state and country — the treatment of manufacturer coupons, shipping charges and mixed taxable/non-taxable line items differs, so a novel case is a question for your tax authority or accountant, not a calculator. Second, many services are not taxable at all in a given state; if you are a freelancer invoicing for labour, the correct tax rate may simply be 0%, and charging 8% because the field was there is worse than charging nothing.
On the payment-terms side, the rule of thumb that survives contact with reality is that shorter terms get paid sooner: Net 15 tends to be paid faster than Net 30, and an explicit due date beats "Net 30" for the same reason a deadline beats a duration. State the late fee in the contract before you ever need it.
Taxing shipping when your state does not tax it, or not taxing it when it does. This is the single most common sales-tax error on small-business invoices, and it goes both ways.
Rounding each line, then summing. Round once, at the total. Per-line rounding on a long invoice drifts by cents that then never reconcile against the payment.
Reusing an invoice number. Two invoices with the same number is the fastest way to lose a payment dispute and to confuse your own books. Number sequentially, never reuse.
Treating the invoice total as revenue. The $80 of tax in our example is not yours — it is money you are holding for the state. Booking $1,080 as income overstates revenue and understates the liability you owe at filing time.
One invoice is a calculation. A business is a ledger: which invoices are out, which are overdue, how much tax you have collected but not yet remitted, and what each client has actually paid. None of that fits in a calculator, because all of it is state that has to persist between invoices. Our Client Tracker & CRM keeps quote, invoice and payment in one pipeline, and the Small Business Bookkeeping workbook keeps the collected-tax figure separate from revenue so it is still there at filing time. Use this page to total an invoice; use a sheet to know what you are owed.
Take the subtotal, subtract any discount, then add sales tax on what's left. This tool shows the discount, tax, and final total for you.
Usually after — the discount comes off the subtotal first, then tax is charged on the reduced amount. That's how this calculator works.
Related: late fee calculator · sales tax calculator · freelance rate calculator.
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Yes. The Invoice Total Calculator is completely free, runs in your browser, and never asks for a signup, email, or download. Enter your numbers and the result updates instantly.
It uses standard formulas and recalculates the moment you change a value, so the math is exact for the inputs you enter. Treat the result as a reliable planning estimate; for decisions with legal or tax consequences, confirm the figures with a qualified professional.
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Last reviewed: September 2026. Free to use, no signup — Invoice Total Calculator by ToolWise Digital.
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