Menu

Invoice Number Generator

Choose a format, a prefix and the first number. The list updates as you type, and you can download it as a TXT or CSV file.

Last updated

Printed in capital letters. Left empty, INV is used.

From 1 to 5,000.

First number

INV-2026-1001

Next number after this list: INV-2026-1011

10 numbers

  1. INV-2026-1001
  2. INV-2026-1002
  3. INV-2026-1003
  4. INV-2026-1004
  5. INV-2026-1005
  6. INV-2026-1006
  7. INV-2026-1007
  8. INV-2026-1008
  9. INV-2026-1009
  10. INV-2026-1010

What the generator does

It builds a run of invoice numbers from one pattern: each number is the one before it plus one, in the same format. Use it to settle on a numbering system before your first invoice, to carry on a series you started in another tool, to number a book of paper invoices in advance, or to paste a block of numbers into a spreadsheet.

The date parts of a number (year, month and day) use today's date on your device. The default settings start at 1001 with the prefix INV, which gives INV-2026-1001.

How to generate invoice numbers

  1. Choose a format

    Pick one of the five formats, or Custom pattern to arrange the parts yourself.

  2. Type a prefix

    For example INV for invoices. A separate prefix for other documents, such as CN for credit notes, keeps each series apart.

  3. Set the first number

    Continuing an existing series? Enter the number after your last invoice.

  4. Set the digits and the list length

    Minimum digits adds leading zeros, so 7 with four digits prints as 0007. A list holds 1 to 5,000 numbers.

  5. Download the list

    TXT gives one number per line. CSV gives one column with the heading invoice_number, ready for a spreadsheet.

Formats

Examples with the prefix INV, first number 1001 and today's date at the time this page was built:

FormatExampleGood for
Prefix, year, numberINV-2026-1001A short code for the document type, then the year. The year tells you at a glance when the invoice was issued.
Prefix / year / numberINV/2026/1001The same three parts with slashes between them, for systems or customers that expect that style.
Year, month, number2026-09-1001No prefix. The month of issue is part of the number, so a sorted list is also in date order.
Date, number20260927-1001The full issue date, then the running number. Useful when you look invoices up by day.
Number only1001A plain running number with leading zeros. The simplest series to keep in order by hand.
Custom patternINV-2609-1001 (from {PREFIX}-{YY}{MM}-{SEQ})Your own order of parts, built from the placeholders below the form field.

In a custom pattern, {YYYY} is the four-digit year, {YY} the last two digits, {MM} the month, {DD} the day and {SEQ} the running number with its leading zeros.

Setting up an invoice numbering system

  • One number per invoice. Never give the same number to two invoices, even years apart.
  • Count up without jumps. Take the next number every time. If an invoice is cancelled, keep it on file marked as cancelled instead of reusing its number, so a missing number always has an answer.
  • Decide what happens in January. With the year in the number you can restart at 1 each year or keep counting. Pick one and stick to it.
  • Give other documents their own series. Credit notes, quotes and receipts with their own prefixes cannot be mixed up with invoices.
  • Leave room to grow. Choose enough digits for the invoices you expect, so the numbers stay the same length and sort correctly.

If you are registered for VAT or GST, your tax authority may have its own rules on invoice numbers. Check them before you settle on a format.

Using the numbers

Type the next number into the Invoice number field of the Free Invoice Generator, or the credit note number into the Credit Note Generator, and download the document as a PDF. The file name includes the number, for example invoice-INV-2026-1001.pdf.

Related tools

Questions

What is a good invoice number format?

One you can keep up for years: a short prefix, the year if you want it, and a running number with enough digits, such as INV-2026-1001. Any of the formats above works, as long as every number is used once and the series counts up.

Can I start at 1001 instead of 1?

Yes. Enter any first number and the generator counts up from there. Starting at 1001 keeps the number four digits long for the first 8,999 invoices.

How do I continue the numbering I already use?

Set the format, prefix and minimum digits so the first number looks like your existing ones, then enter the number after your last invoice as the first number.

What do I do with the number of a cancelled invoice?

Keep the cancelled invoice on file and do not give its number to a new one. If the invoice was already sent, correct it with a credit note that refers to the original invoice number.