Apple iMac (21.5-inch, Mid 2010)

Model identifier iMac11,2 All-in-one, from 2010 57 hardware reports
Memory
Up to 16 GB
4 laptop-size slots
Upgradable

Yes. 4 slots, up to 16 GB seen working.

It takes DDR3-1333 laptop-size sticks (SO-DIMM).

Slots
4 SO-DIMM slots
Type
DDR3-1333 204-pin SO-DIMM
Most seen working
16 GB in two or more machines
Firmware says
16 GB maximum
How sure
28 of 28 reports show this layout
See 4 GB DDR3-1333 SO-DIMM on AmazonOpens an Amazon search for this exact spec.

Worked out from 28 hardware reports of this desktop, with Apple's memory specifications for which Macs have sockets. Sources and method. Updated 10 Nov 2026.

4 laptop-size slots
Illustration

Questions

Can I upgrade the RAM in the Apple iMac (21.5-inch, Mid 2010)?

Yes. 4 slots, up to 16 GB seen working. It takes DDR3-1333 laptop-size sticks (SO-DIMM).

What type of RAM does the Apple iMac (21.5-inch, Mid 2010) use?

DDR3-1333 laptop-size sticks (SO-DIMM, 204-pin).

How much RAM can the Apple iMac (21.5-inch, Mid 2010) take?

Machines in the reports run up to 16 GB. That matches the 16 GB maximum the firmware reports.

Is this my desktop?

On the Mac, choose Apple menu > About This Mac > System Report. The Model Identifier should read iMac11,2.