Invoice Numbering System
A free invoice number generator so you never assign a duplicate invoice number again. Counter is saved to your browser.
Set up a clean invoice numbering system in seconds. This free invoice number generator builds sequential, no-duplicate invoice numbers from a custom prefix, period and padding, then saves your counter to the browser so the next number is always ready.
Configuration
- INV-2026-002
- INV-2026-003
- INV-2026-004
- INV-2026-005
- INV-2026-006
Tips
- →Most tax authorities require invoice numbers to be sequential within a period, so don't skip numbers.
- →Resetting the period (year, fiscal year, quarter) and the counter at the start of each cycle keeps audits clean.
- →Your counter is stored locally. Clearing browser data resets it, so note your last number.
What is a good invoice number format?
A reliable invoice number format combines a short prefix (like INV), a period such as the year or fiscal year, and a zero-padded sequence, for example INV-2026-001. Keeping invoice numbers sequential within each period avoids duplicates and keeps your books audit-ready.
Do invoice numbers have to be sequential?
Most tax authorities require sequential invoice numbers within a period with no gaps, which is exactly what this invoice numbering system produces.
Is my counter saved?
Yes. The current invoice number is stored locally in your browser, so the next number is ready whenever you return. Clearing browser data resets it.