How Much RAM

As of early 2019, the lowest amount of RAM any new Mac ships with is 8 GB, though millions of Macs that are in active use—and capable of running the latest version of macOS—shipped with as little as 4 GB (and some Macs that can run 10.13 High Sierra shipped with only 2 GB). In my opinion, 2 GB is such an absurdly small amount that it virtually guarantees poor performance, and even 4 GB is inadequate for most people. macOS itself uses so much RAM that if you have 4 GB or less, you’ll be severely restricted in how many apps and files you can open before virtual memory begins swapping memory to disk. That swapping slows you down significantly, especially if your Mac has a mechanical hard drive (an SSD, such as the one in the MacBook Air, can compensate to some degree).

At the other end of the spectrum, the Mac Pro (2013) and the iMac Pro can hold as much as 128 GB of RAM. Based on today’s software, very few people can productively keep that much RAM busy, which is fortunate because very few people can afford that much RAM!

For most people and most common activities, I believe something in the range of 8 to 16 GB should be sufficient. At those quantities, RAM is fairly inexpensive compared to the price of a new Mac, and the incremental cost of an extra 4 or 8 GB is usually quite small. So it pays to add as much as you can, within reason.

Unfortunately, not all Macs offer the option to upgrade their RAM after purchase. If you have any currently shipping Mac laptop, the RAM is not user-upgradable. In some models, like the iMac Pro and the Mac mini (2018), you can upgrade the RAM, but only with the equivalent of major surgery. For non-upgradable models, if you want more than the base amount, you have to add it to your configuration when ordering your Mac.

If you buy a new Mac without user-upgradable RAM, select the configuration with the highest amount of RAM you can afford. For owners of Macs that do have user-upgradable RAM, however, here are my suggestions:

• If your Mac has a capacity of 8 GB of RAM or less, install the maximum it can hold.

• If your Mac has a capacity of 16 GB and you can afford it, install 16 GB; otherwise, give it at least 8 GB.

• If your Mac has a capacity of 32 GB or more, install at least 16 GB. Go above that only if you learn from Activity Monitor or other tools that you’re generating lots of pageouts—and if you can afford it! If you’re doing massive scientific calculations or high-definition video editing, you may very well benefit from 64 GB of RAM or more. Most ordinary folks, however, will be just fine with 16 GB.

• If you buy a new Mac with user-upgradable RAM, check to see not only how much RAM it includes but also how the modules are configured. If you plan to upgrade your RAM later, it helps to know whether you’ll have to replace any of the existing modules to get to your desired total. (If you order your Mac from the online Apple Store, the configuration page shows you this info.) Sometimes Apple gives you the choice—for example, 16 GB in the form of four 4 GB modules or two 8 GB modules. Usually the option that leaves you with the greatest number of empty slots is the most flexible and cost-effective.

• If you buy a new Mac without user-upgradable RAM but with extra RAM available as a build-to-order option, consider configuring it with the next notch above the minimum amount. That will decrease the likelihood that you’ll regret your decision in a year or two, when you’re running more or fancier apps and could really use that additional RAM.

Where to Buy RAM

You can find Mac-compatible RAM nearly anywhere—both online and in brick-and-mortar computer stores. Apple uses industry-standard RAM modules, but their specifications are quite demanding. Lots of Mac users, including me, have had bad experiences with cut-rate or generic RAM because even though it appeared to meet Apple’s criteria on paper, the manufacturing tolerances weren’t up to the standards of the RAM Apple installs at the factory.

Of course, you could have Apple install lots of extra RAM when you purchase a new Mac—and in some cases that’s your only option—but Apple’s own RAM is often overpriced (at least for larger modules).

So my advice is to buy name-brand RAM from reliable suppliers—preferably those with extensive experience with Macs, so you’re assured of getting just the right type—and always look for a lifetime guarantee.

I generally buy RAM from Other World Computing, which meets all those standards and has competitive prices. It’s also worth checking out DealNews, which tracks RAM prices from many distributors and can help you find good deals—keeping in mind the caveats I just mentioned.

I recommend against buying used RAM, and I also suggest staying away from eBay—even for new RAM. Because quality RAM is so central to your Mac’s health, I counsel you not to take any risks just to save a few dollars.

How to Install RAM

Even if you’re squeamish about opening up your Mac, RAM is usually pretty easy to install; Apple tends to make it reasonably easy to reach, if it’s accessible at all. (And adding RAM won’t void your warranty, except in the unlikely event that you break something else in the process.) For example, on the latest non-Pro iMac models, you need merely turn off the computer, push a button to pop off a little cover on the back, lift a lever, pop in the RAM module(s), and replace the cover.

Unfortunately, the same cannot be said for MacBook Pro models with upgradable RAM, which require the removal of numerous tiny screws, and older Mac mini models, which were notoriously difficult to open, even with the obligatory putty knife.

If you’re wondering how to install your new RAM, the first thing you should do is look through the papers that came with your Mac. Most of them include a little Getting Started booklet that includes illustrated instructions for adding RAM. If you don’t have that booklet, check Apple’s Support site to find directions.

Alternatively, Other World Computing has video upgrade guides; also check iFixit, which has nicely illustrated instructions for many Macs. Note that if you install your own RAM, you may need to obtain special screwdrivers to disassemble your Mac; the sites I just mentioned tell you exactly what you need.

Still anxious? One option is to find a technically savvy friend or family member who’s willing to do the work (and to whom you’re willing to entrust your precious Mac!). As a last resort, any Apple Authorized Service Provider will do the work—but it won’t be cheap.

Choose a New Drive

Countless hard drive models exist, with more appearing every day. The choices may seem daunting, but I can simplify them for you. When selecting a drive, focus on the following things, in this order:

• Physical size: If you don’t have a drive with the right form factor, you’ll get stuck before you even get started. Older Mac laptops, and all models of the Mac mini, use 2.5-inch drives; iMacs and tower-style Mac Pros use 3.5-inch drives (though 2.5-inch drives can be made to work with an adapter). The Mac Pro (2013), the MacBook Pro (Retina), and the MacBook Air all use special solid-state storage modules rather than conventional 2.5- or 3.5-inch mechanisms.

• Capacity: Be sure to select a drive with enough capacity for both your current needs and what you imagine your needs to be over the next few years. As I write this in early 2019, you can buy 3.5-inch drives that hold up to 14 TB, and 2.5-inch drives that hold up to 5 TB. Those numbers will certainly increase over time. Higher-capacity drives are almost always more expensive than lower-capacity drives with similar specs, and in some cases you may need to choose between higher capacity and higher speed.

• Rotational speed: This is the speed at which the hard drive’s platter or platters spin. All other variables being equal, higher rotational speeds mean faster performance—but faster drives also tend to consume more power (draining laptop batteries faster), generate more heat, produce more noise, and cost more. The vast majority of hard drives intended for consumer equipment spin at either 7200 rpm (typical for desktop computers) or 5400 rpm (typical for laptop computers), although you may see other speeds (such as 5900, 5200, and 4200) occasionally.

Now let’s pause. At this point, you may have decided that you want, for example, a 2.5-inch, 2 TB, 5400 rpm drive, or a 3.5-inch, 4 TB, 7200 rpm drive. Now that you’ve narrowed down your options, you may have very few models from which to choose, and you can simply look at the price and make your decision. However, if many drives match your criteria and you need to zero in further, look at cache (buffer) size and data transfer rates (larger numbers are better); seek times, latency, and power consumption (smaller numbers are better); and warranty (longer warranties are better). But in reality, all these factors make little real-world difference.

However, before you hand over your credit card, you may want to consider whether it would be better still to spend a bit (or a lot) more money to get one of the following drive types:

• SSD: Solid-state drives (SSDs) are way, way faster than even extremely fast hard drives. They use less power, generate less heat, make no noise, and are shockproof. They’re also expensive, and they may not have as much capacity as you want. But the benefits might outweigh the cost. Read Add an SSD for details.

• Hybrid: A hybrid drive (sometimes referred to as an SSHD, or solid-state hybrid drive) combines a conventional hard drive mechanism with a modest amount of flash RAM (say, 4 or 8 GB) and special firmware on the drive itself that enables the drive to intelligently keep the most frequently accessed data cached in that RAM. The effect is that many data transfer operations are just as fast as with an SSD, while the price is much lower than a full SSD of the same total capacity.

  Real-world performance will depend heavily on how you use the drive, but if you can find a hybrid with the size, interface, and capacity you want, it’s certainly worth a few extra dollars for the potential speed boost.

Install a Hard Drive

Swapping an old hard drive for a new one—and preserving all your data in the process—isn’t as daunting as it may sound. It takes time, but most of that time is simply waiting for data to copy. Rather than go into all the gory details, let me simply outline the steps needed; if you find these too vague, I suggest that you conscript your friendly neighborhood geek, or hire a professional, to do them for you.

Here are the basic steps:

1. Obtain an external (USB, Thunderbolt, or FireWire) enclosure or adapter that can accommodate your new drive, put your new (empty) drive in it, and hook it up to your Mac.

2. Use Disk Utility to partition and format your new drive in the manner your Mac requires. In most cases I suggest a single partition, using the GUID Partition Table scheme, and the Mac OS Extended (Journaled) format.

3. (Re)start your Mac in safe mode to avoid loading background tasks that might change the data on your drive while you’re in the process of copying it.

4. Using your favorite cloning tool, such as Carbon Copy Cloner or SuperDuper!, copy the entire contents of your old drive onto your new one, creating a bootable duplicate.

5. Restart again, holding the Option key down; select your external drive when the available startup volumes appear and then press Return. Verify that your new drive successfully boots your Mac and everything seems to work as expected. If it doesn’t, repeat step 4 or seek further troubleshooting help; if your drive won’t start your Mac when it’s outside the Mac, it won’t start it from the inside either.

6. Shut down your Mac.

7. Open your Mac and the external drive case; swap the two drive mechanisms. As I suggested earlier in the context of installing RAM, you can find video upgrade guides from Other World Computing and illustrated instructions for many Mac models at iFixit. Close up your Mac.

8. Restart your Mac while holding down the Option key; select the new internal drive and press Return. Your Mac should now boot from the new internal drive that has an exact copy of the data that was on your old drive.

9. Finally (and very important), go to System Preferences > Startup Disk and select your new internal disk as the startup volume.

Now you have your old drive in an external case (or an adapter that can attach it without a case). You can use this drive for backup or scratch space, or simply as extra storage for your files.

Choose an SSD

Just like hard drives, SSDs come in various form factors (such as 2.5-inch and 3.5-inch, plus special designs that work with only particular Mac models), capacities, and speeds.

In general, I suggest following the same advice I offered in Choose a New Drive when selecting an SSD. Also, be aware of the following:

• Even a slow SSD is likely to be much faster than a fast hard drive. So don’t agonize over data transfer numbers. If you can find an affordable SSD that’s a bit slower than a more expensive one, you’ll probably still be happy with it.

• Either your budget or drive availability may force you to buy a smaller capacity than you prefer. Even so, get the largest SSD you can reasonably justify paying for, because the more data you can store on the drive, the more opportunities there are for performance improvements.

• Some SSDs are more reliable than others, have built-in data encryption features, or include other bells and whistles not found on hard drives at all. I suggest that you read as many reviews as you can find before making any purchase and buy from a reputable vendor, such as Other World Computing.

• The MacBook Air (pre-2018), MacBook Pro (Retina, through 2015), and Mac Pro (2013) require specially shaped modules that are available from only a few vendors. Before placing your order, be sure to confirm that the drive you want will fit in your Mac.

Install an SSD

In general, the physical process of putting an SSD into a Mac is identical to that for replacing a hard drive (see Install a Hard Drive), except that SSDs usually come in a 2.5-inch form factor, which means you’ll need an inexpensive adapter (possibly included with the drive) if you want to replace a 3.5-inch drive. Other than that, if you’re swapping a hard drive for an SSD, there’s usually nothing special to know on the installation side.

Much more challenging than the hardware swap is moving from a higher-capacity hard drive as your startup volume to a lower-capacity SSD. What do you do with the rest of your data?

In my opinion, the optimal procedure is to use your Mac’s existing hard drive as a secondary drive—ideally an internal one, if your Mac will accommodate it, though an external case will work too—and move only the portions of your data from that drive to the SSD that will comfortably fit. Then simply designate your SSD as the startup disk and point your apps to your secondary disk to find their data.

Here are some specific tips and reminders:

• As I explain later (see Add a Secondary Drive), if your Mac has an optical drive, you can swap that out for a second internal hard drive or SSD and put the old optical drive in an external case.

• If you must put your old drive in an external enclosure, you’ll get the best results with Thunderbolt or with USB 3—more specifically, USB 3.1 Gen 2 (via a USB-C connector) if your Mac supports it, or USB 3.0 (via an old-style USB-A connector) otherwise. You’ll have access to all your data only when the drive is connected, so this is less than optimal for laptop users.

• For media such as music and TV shows, if you normally consume it only when you’re at home, you can store it on another Mac and stream it over your local network via iTunes Sharing.

• If you store data only in the cloud, remember that you’ll be able to access it only when you have an internet connection.

• Since Apple lets you re-download music, TV shows, and movies you previously purchased from the iTunes Store, you can delete any such items to make space without losing them permanently.

• If you subscribe to Apple Music or to Apple’s $24.99-per-year iTunes Match service, you can also delete any matched tracks from your Mac (purchased or not) and then, assuming you keep your subscription active, re-download only those you want to have available at any given time.

• If you use Optimized Storage (see Use Optimized Storage in Sierra or Later), your Mac will be able to delete certain items later to make space, while keeping the originals in the cloud.

• When you choose which data to keep on the SSD and which to keep elsewhere, remember that the most crucial thing to put on the SSD is macOS itself, followed by your Applications folder. If you have room for it, you’ll get the best performance if you can also keep your entire home folder on the SSD. If not, the next best option is to leave off of the SSD only your home folder’s bulkiest items (such as your iTunes and Photos libraries—or at least your iTunes Media folder, for which you can select a new location on the iTunes Advanced preference pane), accessing them from a secondary volume.

• Be sure to give your SSD and your secondary disk different names, both to avoid confusion personally and to prevent errors from apps that may look in the wrong place for their files.

• Once your move to the SSD is complete, be sure you update your backup software, if necessary, to include both the SSD and the secondary disk. (This should be automatic in Time Machine.)

With all those thoughts in mind, I recommend doing the following:

1. While your original hard drive is still in your Mac, follow all the instructions in Free Up Disk Space to get rid of any superfluous clutter. It’ll make things easier.

2. Make a preliminary list of what you should avoid copying to your SSD. To do this, select your current startup disk in the Finder, choose File > Get Info, and note the figure next to “Used.” That’s how much data you have, and if you subtract the size of your SSD, that’s roughly how much you’ll need to leave behind; let’s call that number x. Add to x the amount of free space you should leave on your disk, as discussed in Determine How Much Space You Need (typically 6 GB or twice the amount of physical RAM you have installed, whichever is larger); we’ll call the result y. Begin selecting folders and, using the Get Info command, see how large they are. Your objective is to come up with a list of folders that collectively add up to a bit more than y.

   Suggestions of folders to consider when making this list:

   • Folders you’ve manually created at the top level of your disk

   • Media folders, such as ~/Pictures, ~/Music, and ~/Movies

   • Your Downloads folder, at ~/Downloads by default

   • The /Developer folder, if it exists

   Keep in mind that you won’t lose any of this data; it will simply reside on a different volume, and you can easily tell the apps on your SSD where to look for them later.

3. Now follow one of two approaches:

   • If you were able to come up with a list of folders at least as large as x without having to exclude the Users folder entirely (which is preferable), use Technique A (next).

   • If the only way you can fit macOS and your apps onto the SSD is to skip the entire Users folder, use Technique B (ahead).