Set a prefix, starting number, and format, generate a sequential batch, and export it as CSV. Free, and no signup needed.
| # | Invoice Number |
|---|
No numbers generated yet. Set your format above and click "Generate List."
Once your numbers are generated, use them straight on the invoices you actually send.
A gap or a repeat in your invoice numbering is a small thing that causes a disproportionate amount of pain later, at tax time, during a client dispute, or the day your accountant asks for a full list. This generator builds a clean, sequential batch in the exact format you choose, so every invoice you send carries a number that is unique, consistent, and easy to search for later.
Most small businesses land on one of a few patterns: a simple running number (1, 2, 3), a prefix plus a padded number (INV-0001), or a prefix with a date segment worked in (INV-2026-0001). Padding the number with leading zeros keeps every invoice number the same length, which sorts and scans more cleanly in a spreadsheet or accounting tool than a mix of 1-digit and 4-digit numbers side by side.
Set an optional prefix, the number you want to start counting from, how many digits to pad it to, whether to work a year or year-month segment into the format, and which separator to use between the parts. The preview updates as you type, so you can see exactly what your first invoice number will look like before generating anything. Click "Generate List" for a full sequential batch, then "Export as CSV" to download it.
They do not have to follow any single format, but they should never repeat, and most bookkeeping and tax guidance recommends keeping them sequential with no gaps left unexplained. A skipped or reused number is one of the first things a bookkeeper or auditor checks for, since it can look like a missing or deleted invoice even when nothing is actually wrong. Generating your numbers as a clean batch up front, rather than typing each one by hand as you go, is the easiest way to avoid that problem entirely.
Billbooks assigns and tracks the next invoice number automatically, every time, with no spreadsheet needed.
Try Billbooks FreeFree to start · No credit card needed