Invoicing calculators
Quick, accurate answers for the numbers that go on an invoice.
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Late fee calculator
Enter the invoice amount, the number of days it is overdue and the way your terms calculate the fee. The calculator shows the late fee and the new total using a monthly rate prorated by the day, simple annual interest or a flat fee. Check the result against your contract before you add it to an invoice.
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VAT calculator
Enter an amount, choose a rate and pick add or remove. The calculator shows the net price, the VAT and the gross total. It starts at the UK standard rate of 20%, with presets for the UK reduced and zero rates and for common EU standard rates.
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GST calculator
Enter an amount, choose a rate and pick add or remove. The calculator shows the GST-exclusive price, the GST and the GST-inclusive total. Presets cover Australia, New Zealand, the Canadian GST and every HST province at the rates in force in 2026.
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Hourly rate calculator
Enter the income you want to earn, your yearly business expenses, the hours you can bill each week and the weeks you work in a year. The calculator returns the hourly rate that covers all of it plus your profit margin, and shows the matching day rate and annual revenue.
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Net 30 due date calculator
Enter the invoice date and choose the payment terms. The calculator counts forward in calendar days and shows the due date, the day of the week and a warning if the date falls on a Saturday or Sunday. It covers net 7 to net 90, EOM and net 30 EOM.