Yes, you can copy a standard residential mailbox key at any hardware store in under 5 minutes for $2 to $5. If your mailbox is a USPS-managed cluster box or CBU unit, the answer is no — those keys are restricted and cannot be duplicated at a locksmith or hardware store.
Here's exactly what to do depending on your situation.
Personal Residential Mailbox: Yes, You Can Copy the Key
Most standalone curbside mailboxes use a standard cam lock with a simple key blank available at any Home Depot, Ace Hardware, Walmart, or local locksmith. Bring your original key, ask for a standard key copy, and you're done in 3 minutes for $2 to $5.
If you've lost your key entirely, the fastest solution is to replace the lock yourself. Our Mailbox Lock collection has standard cam locks in 5/8 inch and 3/4 inch sizes starting at $14.90 — cheaper than a single locksmith service call.
The key blank for most residential mailbox locks falls into two categories: flat steel keys and tubular keys. Flat steel keys are by far the most common and can be copied anywhere. Tubular keys — the round ones used on some higher-security locks — require a specialized cutting machine that most hardware stores carry but some smaller locksmiths don't.
💡 Tips : Before heading to the hardware store, take a photo of your key. If the blank isn't in stock, the photo helps the locksmith identify the right blank from a catalog and order it same day.
If you've lost the key entirely and have no copy to duplicate, you have two realistic options. A locksmith can pick or drill the existing lock and replace it on the spot for $50 to $100 including labor and parts. Or you can buy a replacement cam lock for $15 to $30 and install it yourself in 5 minutes with a screwdriver and a wrench — no locksmith needed.
USPS Cluster Mailbox or CBU Unit: You Cannot Copy the Key
USPS-issued keys are federally controlled. The key blank itself is a restricted item, not available in standard locksmith inventory. No hardware store key-cutting kiosk carries it, and no locksmith can legally duplicate it without authorization.
If you've lost your USPS mailbox key, you have two official options.
The first is to visit your local post office and fill out PS Form 1094 — the Application for Delivery of Mail Through Agent. This is the official USPS key replacement form. You'll need a valid photo ID and proof of current address. The fee is typically $20 to $50 depending on your post office, and processing takes 1 to 3 weeks.
⚠️ Warning : Some post offices require an appointment to process PS Form 1094. Call ahead before visiting to avoid making the trip for nothing — wait times vary significantly by location.
The second option, often faster, is to contact your building manager or HOA if you live in an apartment complex or planned community. They often manage key inventory directly and can issue a replacement key the same day without going through USPS at all.
How Much Does Copying or Replacing a Mailbox Key Cost?
| Situation | Where to Go | Cost | Time |
|---|---|---|---|
| Copy residential key (have original) | Hardware store / locksmith | $2–$5 | 3–5 min |
| Lost residential key — replace lock DIY | Hardware store | $15–$30 | 5–10 min |
| Lost residential key — locksmith service | Locksmith | $50–$100 | Same day |
| Lost USPS key — post office replacement | Post office (PS Form 1094) | $20–$50 | 1–3 weeks |
| Lost USPS key — building manager | HOA or property manager | Free or low fee | Same day |
What "Do Not Duplicate" Actually Means on a Mailbox Key
Many mailbox keys have "Do Not Duplicate" stamped on the bow — the part you hold. In most US states this marking has no legal force. It's a request, not a law. A locksmith can copy the key if they have the matching blank in stock.
The only keys where duplication is genuinely prevented are USPS-issued keys and patented restricted key systems. For USPS keys the restriction is enforced through key blank unavailability — the blank doesn't exist in standard inventory. For patented systems like Medeco or Mul-T-Lock, the blank is only available to authorized dealers who require proof of ownership before cutting.
💡 Tips : For standard residential mailbox keys stamped "Do Not Duplicate", any hardware store will copy them without question. The marking only matters on patented or government-issued keys.
When Moving Into a New Home: Replace the Lock, Don't Copy
If you've just moved into a new house, copying the existing mailbox key is the wrong move. The previous owner may have made multiple copies over the years and you have no way to know who has them.
The right call is to replace the lock entirely. A standard cam lock costs $15 to $25 at any hardware store, installs in 5 minutes, and gives you full control over who has access to your mail from day one.
✅ Advice : When moving into a new home, replace the mailbox lock before anything else. It costs less than $25 and takes 5 minutes — cheaper and faster than changing the front door lock, and just as important for your mail security.
For a USPS cluster mailbox in a new apartment, contact the post office or your property manager immediately when you move in to request a key reassignment rather than a simple copy.
How to Replace a Mailbox Lock Yourself in 5 Minutes
If you need to replace the lock rather than copy the key, the process is straightforward for any standard residential mailbox.
- Open the mailbox door fully
- Locate the retaining nut or clip on the inside back of the lock cylinder
- Unscrew the retaining nut counterclockwise with a small wrench
- Pull the old lock cylinder out from the front of the door
- Check the diameter of the old cylinder — most are 5/8 inch or 3/4 inch
- Insert the new lock cylinder of the same diameter through the front
- Thread the retaining nut back on from inside and tighten firmly
- Close the door and test the new key several times before considering the job done
Keyless Options: Eliminate the Key Problem Entirely
If you regularly lose keys or share mailbox access with multiple people, a keyless mailbox lock removes the problem at the root. Instead of managing physical keys, you use a push-button combination code that you can change anytime.
Our Digital Lock for Mailbox fits most standard residential mailbox door thicknesses between 1 and 2 inches, runs on a standard battery, and installs in under 10 minutes using the same process as a standard cam lock replacement.
✅ Advice : If you've lost your mailbox key more than once in the past year, upgrading to a keyless lock pays for itself after the first avoided locksmith call. At $29.90 it costs less than a single service call.
FAQ
Can Home Depot copy a mailbox key?
Yes, for standard residential mailbox keys. Their key-cutting kiosks stock most common cam lock key blanks and can cut a copy in under 5 minutes. They cannot copy USPS-issued keys or restricted patented key blanks — those require going through the post office or an authorized dealer.
What do I do if I lost my mailbox key and have no copy?
For a personal mailbox, replace the lock — it costs $15 to $30 and takes 5 minutes. It's faster and cheaper than a locksmith service call. For a USPS mailbox, visit your local post office with a valid ID and proof of address and submit PS Form 1094 for a replacement key.
How long does USPS take to replace a mailbox key?
Typically 1 to 3 weeks after submitting PS Form 1094. Processing times vary significantly by post office location. Call ahead to confirm current wait times before visiting — some offices process replacements faster than others.
Can a locksmith open my mailbox without a key?
Yes. Most locksmiths can pick or drill a standard residential cam lock in a few minutes. Expect to pay $50 to $100 for the service call, plus $15 to $30 for a replacement lock if the cylinder is drilled out in the process.
Is it illegal to copy a mailbox key?
For personal residential mailbox keys, no — copying is legal in all US states regardless of any "Do Not Duplicate" marking. For USPS-issued keys, duplication is prohibited under federal postal regulations and considered mail security tampering.
What size cam lock do I need to replace my mailbox lock?
The two most common sizes are 5/8 inch and 3/4 inch diameter. Remove your existing lock and check the diameter printed on the cylinder body before ordering a replacement to make sure you get the right fit.
Can I rekey my mailbox lock instead of replacing it?
Rekeying is only worth doing if the cylinder is in good condition and you simply want a different key. If the lock is worn, stiff, or has been tampered with, replacing the entire cylinder for $15 to $25 is faster and more reliable than rekeying.
