MacBook Pro with Retina display 13-inch vs. 15-inch: Which powerful Mac laptop is right for you?

You're going to buy a new Mac, and you've narrowed your choice to one of Apple's new sleek, speedy MacBook Pros with Retina display. Seems like an easy choice, doesn't it? Just decide which screen size is right for you: 13-inch or 15-inch, then pull the trigger. Not so fast. There are other considerations you should make, as well. Because screen size isn't the only different between the two machines. This guide should help you iron out some of them.

Note: Updated with info on 2015 models

What is a Retina display, anyway?

First of all, what makes a Retina display "retina?" It isn't a specific resolution or color gamut — it is, instead, a somewhat subjective determination. Apple coined the term "Retina display" to describe any display that, held at an average operating distance, produces imagery with indistinguishable pixels.

Both MacBook Pros with Retina display use screens with similar pixel densities — that is the number of actual pixels displayed by the screen within a single inch (pixels per inch, or PPI). The 13-inch model's pixel density is about 227 PPI while the 15-inch model's is about 220. While that's lower than the iPhone, for example (326 PPI), it's almost twice the density of "regular" MacBook Pro models. Set side by side with "standard" resolution displays, MacBook Pros equipped with Retina displays show sharper text, richer color and more image detail.

It's worth noting that both Retina MacBook Pros have significantly higher native resolutions that what you'll normally see. The 13-inch model's display has a native resolution is 2560 x 1600 pixels, though 1680 x 1050 is the highest resolution accessible through the Display system preference. Likewise, the 15-inch model has a 2880 x 1800 native resolution, though the scaled resolution is limited to 1920 x 1200 pixels — the same as the native resolution of the discontinued 17-inch MacBook Pro.

Apple does that for legibility — truly native resolution would produce almost unreadable text and really tiny pictures. But if you want to give native display operation a try, you can install a third-party utility that unlocks custom resolutions like SwitchResX.

Comparing Retina MacBook Pro models

Starting at $1,299, the 13-inch Retina MacBook Pro comes equipped with a 2.7 GHz dual-core i5 processor, 8 GB RAM and 128 of PCI Express-based flash storage. It uses Intel Iris integrated graphics. The 13-inch Retina MacBook Pro measures 12.35 x 0.71 inches closed and weighs about 3.46 pounds.

A $1,499 Retina MacBook Pro model doubles storage capacity, and for $1,799 you can get a system equipped with a 2.9 GHz i5 processor, 8 GB RAM and 512 GB storage. You can configure to order systems with up to 16 GB RAM and 1 TB of flash storage if you prefer.

The 15-inch Retina MacBook Pro starts at $1,999. For that you get a processor that's clocked at 2.2 GHz, but it's a quad-core i7 processor — better for applications and system processes that are optimized for multithreading (many video applications, audio applications and big chunks of OS X code are). 16 GB RAM and 256 GB flash storage come standard. Intel Iris Pro graphics come standard. A 2.5 GHz system with 16 GB RAM and 512 GB flash costs $2,499. That premium model is also the only Retina MacBook Pro to include a discrete graphics chip — the AMD Radeon R9 M370X, with 2GB of dedicated VRAM. Like past models, that system will automatically switch graphics from the lower-power Iris Pro to the higher-power AMD chipset depending on what's needed.

Closed, the 15-inch Retina MacBook Pro measures 14.13 x 0.71 inches — same height as the 13-inch model — and weighs just a pound more.

Apple's standard suite of application software is included on both MacBook Pros; you get the iLife (iMovie, iPhoto, GarageBand) and iWork (Keynote, Pages, Numbers) apps, along with Safari, Mail and a number of other apps and utilities. OS X Yosemite is also standard issue.

Dual core vs. quad core

13-inch Retina MacBook Pros come standard with dual-core processors while 15-inch models come with quad-core processors. At first glance, it looks like the 13-inch models are faster: Indeed, they have higher clock speeds than the 15-inch models. But the 15-inch models have twice the number of internal cores, which means that — at least for multithreaded applications and system processes — the 15-inch models can perform twice as many tasks in the same amount of time as the 13-inch models.

Most general users can get away with a dual-core processor and not suffer any problems. But if you're doing graphics or video work, rendering 3D or other seriously processor-intensive work, consider a quad-core processor. More cores means the processor is able to juggle more balls at once without skipping a beat — great for ripping video in Handbrake, for example, or running computationally-intensive operations (often used in math, science and engineering software). For graphics-intensive stuff, also consider the discrete graphics chip on the higher-end 15-inch Retina MacBook Pro — more on that in a bit.

One way or the other, unless you have a real edge case, it's probably not worthwhile to invest a lot of money in processor upgrades for your Retina MacBook Pro — go with one of the pre-configured systems unless you really need some incrementally improved horsepower.

Memory: The non-upgradable dilemma

The 8 GB included on the low-end 13-inch Retina MacBook Pro is adequate to run most application software. If you're planning to run memory-intensive stuff like Photoshop with big images, or are doing digital video or digital audio work, consider bumping it up to 16 GB.

Storage vs. affordability: Get the SSD balance right

Retina MacBook Pros eschew conventional hard disk drives for Solid State Drive (SSD) instead; the net result is that they're able to be thinner and faster, with better storage system reliability than before. Both 13- and 15-inch Retina MacBook Pros sport very fast SSDs; twice as fast as previous models.

It's probably a good idea to configure your Retina MacBook Pro with as much storage as you can reasonably afford right off the bat (the 128 GB standard SSD on the $1,299 13-inch Retina MacBook Pro is skimpy, but it's the lowest-priced model). There aren't any available third-party SSD upgrades for current MacBook Pro models, though that may change in the future.

Integrated graphics vs. discrete graphics: A question of speed, price and battery efficiency

The 13-inch MacBook Pro features Intel Iris graphics — the next step up from the Intel HD Graphics 6000 found on the MacBook Air, which itself was much faster than the integrated graphics found on last year's processors.

Iris graphics differentiate themselves from the 6000 by having a higher clock speed, so you're able to get more done in less time. Iris Pro, standard on the 15-inch model, gains a 128 MB cache of embedded DRAM to speed things up further.

The $2,499 Retina MacBook Pro adds AMD Radeon R9 M370X. This graphics subsystem is ordinarily only activated when an app or process launches that demands extra graphics horsepower. Games are an obvious example. So is Adobe Photoshop. Even Apple's own iPhoto will force the faster graphics to come on. When that discrete graphics processor kicks in, battery efficiency drops like a stone. But that's the price you pay to have extra graphics oomph when you need it.

Bottom line: the more you spend, the faster your graphics get. If you need the fastest possible graphics in your next laptop, be prepared to shell out for a 15-inch Retina MacBook Pro.

One area free of choices for you: Expandability

All current Retina MacBook Pros come identically equipped with two USB 3 ports, two Thunderbolt 2 ports, a headphone jack, dual microphones, an HDMI connector and an SDXC card slot.

Thunderbolt 2 offers twice the bandwidth of the original Thunderbolt — 20 gigabits per second — which means even faster peripheral connectivity than before. Thunderbolt can be adapted for a wide variety of applications, including fast RAID drives, Gigabit Ethernet or more exotic networking options like Fibre Channel, and more.

Perhaps the most frequent application for Thunderbolt, however, is the use of external displays (Apple sells Thunderbolt adapters to fit different display interfaces like DVI, VGA and HDMI). And the Thunderbolt 2 ports on the Retina MacBook Pro are capable of driving two external displays at up to 2560 x 1600 resolution with millions of colors. What's more, that HDMI interface can drive a 4K display.

Retina MacBook Pros also come with 802.11ac Wi-Fi networking, the faster Wi-Fi standard first introduced with the MacBook Air's refresh earlier in 2013. Called "gigabit Wi-Fi," the faster standard works up to three times the speed of 802.11n, though it requires pairing with an 802.11ac-compliant base station (like Apple's new towering AirPort Extreme and Time Capsule). Both systems also come standard with Bluetooth 4.0 and full-sized backlit keyboards.

Who should buy a 13-inch Retina MacBook Pro?

The base-model Retina MacBook Pro is more than the base-model 13-inch MacBook Air, but comes twice the RAM. While it weighs more, it's a lot more powerful under the hood — faster processor, better expansion and a dramatically better screen.

For most general users, the 13-inch Retina MacBook Pro is the sweet spot between performance and price, and it should be a great replacement for older laptops — one area where it's particularly better is in battery life, which will be a welcome respite for you if you're used to carrying your power adapter around with you.

I'd argue that you should spend the extra money to get the $1,499 model that includes 256 GB flash storage — that'll hedge your bet a bit about what the future might hold for OS X system requirements and application needs.

Who should buy a 15-inch Retina MacBook Pro?

The 15-inch Retina MacBook Pro is the no-compromises king of Apple's laptop line. It has the most capable processors, the fastest graphics and the highest resolution. It's superior to the 13-inch Retina MacBook Pro by just about any measure. All that capability has a price — starting at $1,999.

The Iris Pro integrated graphics in the low-end 15-inch Retina MacBook Pro is certainly an improvement over what came before, and it's fine for low-power work. But the benchmarks I've seen show that the $2,499 15-inch model blows away its lower-priced sibling in graphics tests by as much as two to one.

So if you're a content creator, especially if you're working with pro audio, video or high-resolution graphics — and you're looking for the best system to get your work done, I think the high-end 15-inch Retina MacBook Pro is worth the money. You get a faster machine, double the RAM and half a terabyte of flash storage for another $500.

Still undecided?

If you still can't decide with Retina MacBook Pro is the right one to choose from, I'd recommend dropping by our MacBook Pro discussion forum and posting a question there. iMore has a great online community that can help answer questions and offer advice based on their own experience. You're also welcome to post comments here.

I've had my say, now I want to hear from you. Which Retina MacBook Pro do you currently use? Which one do you want? Or have you ruled the Retina MacBook Pro out all together? Please post your comments, critiques and questions.