The short answer
An N-number is the registration mark of a US civil aircraft, always beginning with the letter N followed by 1–5 characters. Every N-number is unique: at any moment it is assigned to one aircraft, reserved by one holder, or available to claim.
Format and status
Valid formats are digits only (N12345), digits plus one trailing letter (N1234A), or digits plus two trailing letters (N123AB); the letters I and O are never used. The FAA maintains both the registry of assigned tails and a reserved list, where an individual can hold a specific N-number for $10 per year.
Reserved N-numbers that aren't renewed are scheduled for release on a purge date, after which they become available to new registrants — which is how sought-after short or personalized tails come back into circulation.
Related terms and reading
Keep every hour and inspection straight
Maggneto tracks engine times, inspections, and ADs from your actual logbooks — so terms like these become numbers you can act on. Browse the full maintenance glossary.
Frequently asked questions
How do I check if an N-number is available?
Check it against both the FAA registry (assigned tails) and the FAA reserved list. Maggneto's free availability checker does both in one lookup and gives an Available, Taken, or Reserved verdict with the purge date when one is scheduled.