Mac RAM Upgrade: Options, Limits and Prices

Can you upgrade the RAM in a Mac?

For any Mac with an Apple M-series chip, no. Apple silicon Macs keep their memory inside the M-series chip package, so there is no slot and no stick to swap. The amount you choose when you order is the amount the machine has for its whole life.

Some older Intel Macs are different. Among iMacs and MacBook Pros, the 27-inch iMac from Late 2009 to 2020 and the MacBook Pro from 2008 to Mid 2012 have memory slots you can open yourself, and they take ordinary SO-DIMM laptop modules. For everything else, the real decision happens at the checkout.

If you want the basics first, our guide to what RAM is and what it does explains why a Mac slows down when memory runs out. Below you will find the current Apple silicon options, a check for whether you need more memory at all, the older models with slots, and what matching modules cost at Amazon.co.uk, AWD-IT, Box, CCL, Laptops Direct, Overclockers UK and Scan this week.

Apple silicon: pick the size when you buy

Apple is explicit about the Mac mini: on every model from M1 (2020) to M6, the memory is integrated into the chip and cannot be upgraded. It says the same about the 24-inch iMac released in 2021 or later. The unified memory design is shared by all Apple silicon Macs, which covers the MacBook Air and MacBook Pro with an M-series chip too.

So the only memory upgrade on a current Mac is a build-to-order option on Apple's store. On the UK store, the MacBook Air with M5 starts at £1,299 for the 13-inch and £1,499 for the 15-inch, with 16GB, 24GB or 32GB of unified memory chosen before you pay. The table below shows the memory steps Apple lists for its current notebooks.

A bigger SSD or an external drive gives you room for files, not working memory, so it does not fix a Mac that runs short of RAM. Plan the memory for the years you expect to keep the machine. If you are unsure what size suits your work, our guide on how much RAM you need gives rough tiers per use case.

The memory shortage makes that choice heavier. The Guardian reported in May 2026 that Apple raised the UK starting price of the MacBook Air by £100 while doubling its base storage. TrendForce expects DRAM supply to stay tight in 2027 and says notebook brands may cut memory capacity to control costs. Nobody can say yet how Apple's own memory surcharges will move. Our explainer on the RAM shortage covers why memory got expensive.

Is your Mac short of memory?

Before you spend on a new Mac or on sticks for an old one, check whether memory is the bottleneck. Open Activity Monitor and pick the Memory tab. It lists Physical Memory (the RAM installed), Memory Used, App Memory, Wired Memory, Compressed and Swap Used, plus a Memory Pressure graph.

Apple says you can use that graph to judge whether your Mac could use more RAM. If pressure stays low during your normal work, more memory will change little. If it climbs often and Swap Used keeps growing, the Mac is leaning on its SSD to make up for missing RAM, which is when apps start to feel slow.

On an Apple silicon Mac, the answer to high pressure is a new machine with a larger configuration, or fewer apps open at once. On a 27-inch iMac or an early MacBook Pro, a module swap may be enough. The Physical Memory figure also tells you what you have now, which you need for the tables below.

Older Intel Macs with memory slots

Apple's MacBook Pro memory page lists only the 13-inch, 15-inch and 17-inch models from 2008 to Mid 2012 as having removable memory. Apple adds that laptops not on that list have non-removable memory, so a 2015 MacBook Pro keeps the RAM it shipped with.

The 2011 and Mid 2012 MacBook Pro models have two SO-DIMM slots for 204-pin DDR3. The 2011 models use 1333MHz modules and the Mid 2012 models 1600MHz. Apple gives a maximum of 8GB for both, as two 4GB modules.

With the iMac, screen size decides. The 27-inch models from Late 2009 to 2020 have four slots you can reach yourself. On the 21.5-inch iMac from Late 2012, Late 2013, Mid 2014, 2017 and 2019, Apple says users cannot remove the memory, though an Apple Authorized Service Provider may offer an upgrade. The Late 2015 21.5-inch models cannot be upgraded at all.

This table sums up Apple's figures for the 27-inch iMac.

The 2020 model shipped with 8GB, and Apple describes its memory as unbuffered and non-parity. In plain terms, these are standard laptop modules. Server style registered or ECC sticks are a different product, as our page on ECC RAM explains.

Buying RAM for an older Mac in the UK

You do not need memory with an Apple logo on it. The Macs with slots use SO-DIMM, the compact laptop module that UK shops stock for Windows notebooks as well. What has to line up with Apple's spec for your model is the generation (DDR3 or DDR4), the speed and the capacity of each stick. The generations are keyed differently, so a DDR4 module will not go into a DDR3 slot, and a desktop DIMM is too large for any of these machines. Our RAM compatibility guide goes through those checks in more detail.

The table shows, per type and size, how many laptop kits we found this week and the cheapest one. The rows mix speeds and stick counts, so check both in the product listing before you buy.

Speed is the field to watch with DDR4. Apple names 2666MHz for the 2019 and 2020 iMac and 2400MHz for 2017, yet many DDR4 laptop kits are sold at faster speeds. Whether a faster module settles at the iMac's speed in every case is something we have not been able to confirm, so buying at the speed Apple lists is the cautious route. That is why the table has a separate 2666 row.

Every laptop kit with this week's price is on our laptop RAM page, and the DDR4 laptop RAM prices page lists the modules for the 2017 to 2020 iMac. All prices are including VAT, last checked on 2 November 2026. For the general steps of fitting a module, see our guide on how to upgrade RAM.

Common mistakes

• Shopping for sticks before checking the model year. The same name covers machines with and without slots. A 27-inch iMac from 2019 takes new modules, a 24-inch iMac from 2021 does not. Find the exact model and year on Apple's support page first.
• Treating the 2015 MacBook Pro as upgradeable. It is a popular second hand buy, but Apple lists only the 2008 to Mid 2012 MacBook Pro as having removable memory.
• Ordering DDR4 for a Late 2015 iMac. The Retina 5K model from Late 2015 still uses 1867MHz DDR3. DDR4 starts with the 2017 model.
• Reading the maximum as a single stick. The 8GB limit on the 2011 and 2012 MacBook Pro is two 4GB modules. The 128GB on the 2020 iMac is four 32GB modules across four slots.
• Taking a 21.5-inch iMac apart for a memory swap. Apple does not treat its memory as user accessible on these models. Ask an Apple Authorized Service Provider instead, if one offers it for your model.
• Picking the base memory on a new Mac to save money now. Nothing can be added afterwards, so a tight configuration stays tight. If your current Mac shows high Memory Pressure, take that as a sign to go one step up.