How to Read Serial and Model Numbers on Devices [Guide]
Serial and model numbers are usually printed at 4 to 6 point size on a label underneath or behind a device, often stamped into metal with no ink. Zoom to 5x to 8x with your phone, angle the flashlight across stamped text to create shadows, and take a photo so you can copy the code without retyping it from memory. Check each character for 0 versus O and 1 versus I before entering it.
Where the numbers are
Support has asked for your serial number, the warranty form wants the model, and you are on your knees behind the television with a flashlight in your teeth. Manufacturers put identification labels where they will not spoil the look of the product, which means the underside, the back, or inside a compartment.
- Routers and modems: a label on the bottom with serial, MAC address, default Wi-Fi name, and often the default password.
- Laptops: the underside, sometimes under a battery or a rubber foot, increasingly laser-etched into the metal.
- Phones and tablets: on the SIM tray, in Settings under About, or by dialing *#06# for the IMEI. Older phones have it under the battery.
- Appliances: a rating plate inside the door frame of a washing machine or dishwasher, inside the fridge on a side wall, or on the back of an oven.
- Televisions and monitors: a sticker on the back panel, often low and near the connectors.
- Power tools and bikes: stamped into the housing or the underside of the frame near the pedals.
- Cars: the VIN at the base of the windshield on the driver's side, and on a plate in the door jamb.
Reading printed labels
Most labels are thermal-printed at a small point size, sometimes with a barcode, and the serial is one line among several. At arm's length it is a gray smudge. Hold your phone about 10 cm away and zoom to 5x to 8x. Tap the label to focus, then take a photo. Reading from the photo is far less tiring than reading live, especially when the label is on the back of a device you cannot easily move.
LoupeLens is useful here because the flashlight and zoom are available in the same view and a single tap focuses and captures. The photo lands in a LoupeLens album, so the next time you need the serial you open Photos instead of climbing behind the furniture again.
A labeled photo also protects against typing errors. Zoom into the image and compare character by character as you fill in a form.
Stamped and laser-etched numbers
Serials pressed into metal, engraved on a laptop base, or etched onto a watch caseback have no ink and no contrast. Under a ceiling light they are invisible. What makes them readable is shadow.
- Turn on the flashlight and zoom to 8x to 10x.
- Tilt the phone so the light hits the surface at a shallow angle, maybe 20 to 30 degrees. The edges of each stamped character now throw a shadow.
- Rotate the device or the phone slowly. Some characters read better lit from the left, others from the right, so take two photos from different angles.
- On a polished surface, dim the flashlight by pressing and holding it and swiping down. Full brightness on brushed aluminum produces a white blob where the serial should be.
If you have no phone flashlight, a desk lamp placed to one side does the same job. The principle is the same: light from the side, look from above.
The characters that cause trouble
Serial numbers are commonly entered wrong because of a few look-alike pairs. Knowing the conventions helps.
| Pair | How to tell |
|---|---|
| 0 and O | Many manufacturers do not use the letter O at all. A zero is often narrower, or has a slash or dot. |
| 1, I, and l | Most schemes skip the letter I. A 1 often has a flag at the top; a lowercase L is rare in serials. |
| 5 and S | The 5 has a flat top and a sharp corner; the S is curved throughout. |
| 8 and B | The B has a straight left side; the 8 is rounded on both sides. |
| 2 and Z | The 2 has a curved top; the Z is all straight lines. |
| Model vs serial | Model numbers repeat across every unit and often include letters like A, M, or a slash. Serials are unique and usually longer. |
When the entry form rejects what you typed, these pairs are the first things to check on your photo.
Special cases
IMEI on a phone
The IMEI is 15 digits and appears in tiny print on the SIM tray of many phones. Dialing *#06# shows it on screen, which is easier, but if the phone does not power on, the tray or the original box label is where to look. Magnify the tray at 10x with light from the side.
Rating plates on appliances
These are often inside a door frame at floor level. Use the rear camera with the flashlight on in LoupeLens, hold the phone low so the lens faces the plate, and tap to take a photo. Then stand up and read the photo instead of lying on the floor. Take a second, wider shot that shows the plate and the appliance together, so the photo identifies itself when you find it in your library a year later.
Router labels
Photograph the router label before you mount it on a wall or slide it behind a cabinet. The default Wi-Fi password and admin address are on that label, and you will want them the next time the connection drops.
Keep a record
Once you have a clear photo of each label, you have a home inventory of serials for insurance, warranty claims, and support calls. Rename or caption each photo with the device name while you still remember which label belongs to what, and photograph the receipt next to the label so the purchase date is in the same place. When a product is sold or recycled, delete its photo so the inventory stays current. Anyone who does a lot of this, including technicians and home inspectors, will find more on tiny component markings in electronics repair with a phone magnifier and reading labels on fuses, cables, and appliances.
Frequently asked questions
Where is the serial number on a router?
On a label on the underside or back of the router, alongside the MAC address and usually the default Wi-Fi name and password. Photograph the label before mounting the router somewhere awkward so you can read it later without moving it.
How do I read a serial number stamped into metal?
Shine a light across the surface from a low angle so each stamped character casts a shadow, then view from above. With a phone, zoom to 8x to 10x, turn on the flashlight, and tilt the phone until the characters appear. Dim the flashlight on polished surfaces to avoid glare.
How do I find the IMEI of my phone?
Dial *#06# and the IMEI appears on screen. It is also in Settings under About, on the SIM tray in small print, and on the original box label. If the phone will not power on, magnify the SIM tray at about 10x with light from the side.
Is it a zero or the letter O in my serial number?
Most manufacturers avoid the letters O and I in serial numbers precisely because of this confusion, so a round character is usually a zero and a vertical stroke is usually a one. Zoom into a photo of the label and compare the character's width with known digits nearby.