Billkeep
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Free toolInvoice total calculator
Several lines, per-line discounts, more than one tax at once, and prices that already include the tax. The same engine that works out a real Billkeep invoice.
Two rates at once covers CGST plus SGST, or GST plus a provincial tax. Compound means that rate is charged on the total including the ones before it.
Working it out…
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What it is doing
Why do the figures always add up exactly?
Because they are made to. A whole-invoice discount is spread back across the lines by largest remainder, and with per-invoice rounding the once-rounded tax is handed back the same way. Amounts are whole pennies throughout — no floating point ever touches money — so nothing drifts.
What does "prices already include the tax" mean?
That the number you typed is what the customer pays, and the tax is taken out of it rather than added on. £120 at 20% is £100 plus £20, never £120 plus £24. Net plus tax equals the price charged, exactly.
On each line, or once per invoice?
Authorities disagree, so it is a choice rather than an assumption. Rounding once per invoice is common in the EU; rounding each line is common elsewhere. With several lines and an awkward rate the two can differ by a penny, which is exactly why it is a setting.
Does it know my tax rate?
No, and it never will. You enter the rates. Which one applies to what you sell is a question for your tax authority or your accountant — this does the arithmetic and nothing else.
Is what I type stored anywhere?
No. It stays in this tab, and closing it is the end of it. There is no account, no cookie for this, and nothing is sent to a server.
Now put a name and a number on it
Billkeep is this calculator with a client attached, a document to send, and a record of who has paid.