Identify Your iMac Model Year: Quick Guide

This guide shows you exactly how to tell which iMac model and year you have, using the serial number, the “About This Mac” screen, and physical details. You’ll learn the fastest methods first, then how to confirm the specific model and year so you can check compatibility, find parts, or look up specs accurately. No special tools are needed — just the Mac itself and a few minutes.

What You’ll Need

Your iMac (powered on, or at least the serial number visible on the underside of the stand)
Internet access (to check the serial number on Apple’s coverage page, or to compare specs)
Optional: a magnifying glass or phone camera to read small text on the underside

Step-by-Step

Click the Apple menu (the logo in the top-left corner of the screen) and select About This Mac. This opens a window showing the macOS version, the chip or processor, memory, and the serial number.
Look for the line that says “Chip” or “Processor.” On newer iMacs (2020 and later), it will say something like “Apple M1” or “Apple M3.” On Intel models, it will say “Intel Core i5” or similar, often with a clock speed like “3.2 GHz.” This immediately tells you the generation family.
Click the “More Info…” button (or the “System Report…” button on older macOS versions). This opens the System Information app. In the left sidebar, under “Hardware,” click “Hardware Overview.” The top line shows the Model Identifier (e.g., iMac21,1 or iMacPro1,1). This is the most precise code for identifying the exact year and model.
Write down the Model Identifier. It looks like “iMac” followed by a number, a comma, and another number (e.g., iMac19,1). This code is unique to a specific model year and configuration.
If you can’t turn the iMac on, flip it over. On the underside of the stand (or the bottom edge of the base), there is a small, embossed or printed text. It includes the model number (e.g., A2115) and the serial number (a 12-character string of letters and numbers). The model number is the key if you know the list; the serial number is the key if you have internet access.
Go to Apple’s coverage check page (checkcoverage.apple.com) and enter the serial number. Apple’s site will show the exact model name (e.g., “iMac (Retina 5K, 27-inch, 2020)”) and the purchase date, which confirms the year.
If you prefer not to use Apple’s site, search the web for the model identifier (e.g., “iMac19,1 specs”). Reliable tech sites (like EveryMac.com or MacTracker) list which model year and screen size each identifier corresponds to. Cross-reference the identifier with the “About This Mac” screen to confirm.
For physical confirmation of the screen size, measure the diagonal of the visible screen area (not the bezel). Common sizes are 21.5 inches, 24 inches, and 27 inches. The 24-inch size only exists on the M1 (2021) and M3 (2023) models. The 27-inch size was discontinued in 2022.
Check the ports. The port layout is a strong clue. For example, the 2021 and 2023 24-inch iMacs have a magnetic power connector and two or four USB-C/Thunderbolt ports, plus a headphone jack. The 2019 and 2020 27-inch models have USB-A ports, two Thunderbolt 3 ports, and an SD card slot. Compare what you see with the known specs for the model identifier you found.
Combine all clues. The model identifier is the definitive answer. The screen size and port layout help you double-check that you haven’t misread the identifier. Once you have the identifier and the screen size, you can state the model year with confidence.

Common Mistakes

Confusing the model number (Axxxx) with the model identifier (iMacxx,x). The A-number is a regulatory code, not a model year. For example, A2115 is used for the 2019 27-inch iMac, but A2116 is the 2019 21.5-inch. They are not interchangeable.
Relying only on the macOS version. The operating system can be upgraded or downgraded. A 2015 iMac can run macOS Monterey (2021), so the OS version is not a reliable indicator of hardware age.
Assuming the purchase date equals the model year. You might buy a 2019 model in 2020 from a reseller. The model year is the year it was released, not the year you bought it. The serial number check will show the actual release year.
Measuring the screen including the bezel. The advertised size is the diagonal of the display panel itself, not the outer plastic frame. Measure only the lit area.
Mixing up the 21.5-inch and 24-inch models. The 24-inch iMac (2021 and 2023) has a flat back and a chin below the screen. The 21.5-inch models (pre-2021) have a curved back and a thicker chin. If you have a 24-inch, you definitely have a 2021 or 2023 model.

Tips

Use the “System Report” button instead of the main “About This Mac” window when you need the model identifier. The main window often hides it behind “More Info.”
Take a photo of the underside text with your phone before you move the iMac. The text is small and can be hard to read if the lighting is poor.
If you have an Intel iMac, the processor name in “About This Mac” often includes the generation. For example, “3.6 GHz Intel Core i9” on a 27-inch model usually means 2019 or 2020, while “3.2 GHz Intel Core i5” on a 21.5-inch model could be 2017 or 2019. The model identifier resolves this.
Bookmark EveryMac.com or MacTracker. These sites maintain complete, searchable databases of every Mac model with its identifier, year, and specs. They are faster than Apple’s coverage page if you just have the identifier.
Check the back of the iMac for a small, recessed button (on 2020 and earlier models). That is the power button, not a model indicator. The model information is never on the back — only on the underside of the stand.

Troubleshooting

If the “About This Mac” window doesn’t show a serial number, click “More Info” and then “System Report.” The serial number is listed under “Hardware Overview.” If it’s still missing, the logic board may have been replaced. In that case, use the underside text.
If the underside text is worn or unreadable, try shining a flashlight at an angle. The text is embossed, so side lighting makes it more visible. If that fails, you can still identify the model by the screen size and ports, but you may not get the exact year without the serial number.
If Apple’s coverage page says “Please enter a valid serial number,” double-check that you typed it correctly. The serial number contains only numbers and uppercase letters (no O, I, or Q). If it still fails, the Mac may be a prototype or a counterfeit — rare, but possible.
If the model identifier doesn’t match any known list, it might be a custom configuration (e.g., an iMac Pro or a special education model). Search the full identifier including the comma and the second number. If you still get nothing, post the identifier on a Mac forum; other users can help.
If you’re trying to identify a broken iMac that won’t power on, and the underside text is unreadable, you can remove the stand (on 2020 and earlier models, it’s held by three screws) to reveal the serial number printed on the bottom of the aluminum housing. This is safe but requires a Phillips screwdriver.
If you have an iMac Pro (2017), it looks different: it’s space gray, has no user-accessible RAM door, and the model identifier is iMacPro1,1. It is not an “iMac” identifier, so don’t search for “iMacxx,x.”

Frequently Asked Questions

Q: What is the difference between the model number (A2115) and the model identifier (iMac19,1)?
A: The model number is a regulatory identifier used for parts and accessories. The model identifier is the internal code that Apple uses to distinguish hardware generations. The model identifier is what tech sites and repair guides use to identify the exact year and specs.

Q: Can I tell the year just from the screen size?
A: Only roughly. A 24-inch iMac is always a 2021 or 2023 model. A 27-inch iMac was made from 2009 to 2020. A 21.5-inch iMac was made from 2009 to 2021. To get the exact year, you need the model identifier or serial number.

Q: My iMac says “Intel Core i5” but I don’t know the year. What else should I check?
A: Check the model identifier (iMacxx,x). For example, iMac17,1 is 2015, iMac18,1 is 2017, iMac19,1 is 2019. The processor name alone is not enough because Intel used similar names across multiple years.

Q: Does the macOS version tell me the model year?
A: No. You can install a newer macOS on an older iMac (if supported), or an older macOS on a newer iMac. The hardware year is fixed; the software is not.

Q: I bought my iMac used. How do I know if it’s been modified or upgraded?
A: The model identifier always reflects the original hardware. If someone upgraded the RAM or SSD, that doesn’t change the identifier. If the logic board was replaced with a different model, the identifier may change to the replacement board’s model. The serial number check will show the original model, which may differ from the current identifier.

Q: Is there a quick way to find the year without the serial number?
A: Yes — use the model identifier. Open “About This Mac” → “More Info” → “System Report” → “Hardware Overview.” The line “Model Identifier” tells you the exact generation. Then compare that identifier to a list (like on EveryMac) to get the year.

General steps for current mainstream versions; menus can differ by device and version. See the disclaimer or report an error.

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