How fast are the "2021 M1" iMac models compared to earlier iMac models? How fast are they compared to each other?

In the press release for the initial Apple Silicon iMac models -- the iMac "M1" 8-Core CPU/7-Core GPU/2 USB-C Shaped Ports (2021) and iMac "M1" 8-Core CPU/8-Core GPU/4 USB-C Shaped Ports (2021) -- Apple uses the word "powerful" eight times and backs it up with specific claims.

Particularly, compared to the 21.5" iMac models introduced two-years earlier, Apple boasts that the "2021 M1" iMac provides:

• Up to 85 percent faster CPU performance, so users can export their favorite video project in iMovie faster than ever, easily work with massive 100-megapixel photos in Lightroom, and compile new apps in Xcode in a fraction of the time.
• Up to 2x faster GPU performance for certain apps like Affinity Photo and Photoshop, and up to 50 percent faster than the most powerful discrete graphics in the fastest 21.5-inch iMac, allowing users to render edits in real time or add complex filters to their photos in a snap.
• The ability to edit up to five streams of 4K footage, or one stream of 8K footage, without dropping a frame in Final Cut Pro.
• Up to 3x faster machine learning in apps that leverage the 16-core Neural Engine in M1.

With detailed performance boasts, it is a good bet that the "2021 M1" iMac models are faster than their exact predecessors.

Photo Credit: Apple, Inc. (Silver Apple Silicon iMac)

However, Apple's performance claims are comparing the "2021 M1" iMac models to the entry-level 21.5" iMac "2019" models replaced rather than the higher-end 27" iMac "2020" models that the company continued to sell as new when it introduced the "2021 M1" iMac line.

Accordingly, it is quite useful to also know how the performance of the "2021 M1" iMac compares to the 27" iMac "2020" models, in particular. It also is helpful to know how the "2021 M1" iMac models compare to each other. It is worthwhile to compare the "2021 M1" iMac to the "Late 2017" iMac Pro, although the iMac Pro was vastly more expensive, as well.

General Performance Overview

For a helpful overview of the performance difference between the "2021 M1" Apple Silicon iMac models and other Macs, EveryMac.com's own Ultimate Mac Comparison makes it quick to compare side-by-side Geekbench benchmark averages with many other Macs for thousands of possible performance comparisons.

This Q&A combines Geekbench 5 benchmarks with our own independent evaluation for a deeper dive into the performance of these Macs.

2021 M1 iMacs Compared to Each Other

In terms of Geekbench 5 benchmarks, the two "2021 M1" iMac models -- the iMac "M1" 8-Core CPU/7-Core GPU/2 USB-C Shaped Ports (2021) and iMac "M1" 8-Core CPU/8-Core GPU/4 USB-C Shaped Ports (2021) -- are the same overall speed.

However, the entry-level model has a 7-Core GPU and the higher-end model has an 8-Core GPU. In many graphics tasks, there is not a notable performance difference between these graphics processors, but third-party tests show that the higher-end graphics processor is on average around 9% faster in graphics benchmarks and on average around 12% faster in some games.

2019 21.5" iMacs Compared to 2021 M1 iMacs

Geekbench 5 confirms that the "2021 M1" iMac models are faster than the "2019" iMac models they replaced, although the higher-end custom processor option for the "2019" iMac holds its own a bit better:

21.5" Intel iMac	24" M1 iMac	Single Core	Multicore
"Core i3" 3.6 (2019)	"M1" 7-Core GPU	+89%	+130%
"Core i5" 3.0 (2019)	"M1" 8-Core CPU	+71%	+58%
"Core i7" 3.2 (2019)		+52%	+21%

It is also worth noting that the "2019" iMac models have RAM and storage that can be upgraded after purchase as well as more ports, but the "2021 M1" iMac models clearly are much faster.

2020 27" iMacs vs. 2021 M1 iMacs

Geekbench 5 demonstrates that the "2021 M1" iMac models top the "2020" iMac models with 27" displays that Apple still sells as new in single core tasks, but actually fall short of higher-end 27" models in multicore tasks:

27" Intel iMac	24" M1 iMac	Single Core	Multicore
"Core i5" 3.1 (2020)	"M1" 7-Core GPU	+52%	+32%
"Core i5" 3.3 (2020)	"M1" 8-Core CPU	+49%	+28%
"Core i7" 3.8 (2020)		+41%	-4%
"Core i9" 3.6 (2020)		+42%	-16%

Of course, these 27" Intel iMacs cost more, but they have larger displays, upgradable RAM, and more ports, as well. It isn't hard to see why Apple decided to compare the performance of the "2021 M1" iMac models to their immediate predecessors from two years ago, though.

2017 iMac Pro vs. 2020 M1 iMacs

Impressively, the "2021 M1" iMac crushes the "2017" iMac Pro in single core tasks, but gets eclipsed by the iMac Pro in multicore tasks:

27" Intel iMac Pro	24" M1 iMac	Single Core	Multicore
8-Core Xeon (2017)	"M1" 7-Core GPU	+60%	-7%
10-Core Xeon (2017)	"M1" 8-Core CPU	+52%	-21%
14-Core Xeon (2017)		+58%	-33%
18-Core Xeon (2017)		+56%	-46%

When it was available new, the "2017" iMac Pro models were much more expensive than the "2021 M1" iMac, as well. This bodes well for future higher-end Apple Silicon-powered iMac models, in particular.

Performance Summary

Ultimately, the "2021 M1" iMac models provide an impressive performance boost compared to their immediate Intel-based predecessors introduced two years earlier, but higher-end Intel-based "2020" iMac models remain quite competitive in some tasks.

Of course, these earlier iMac models are more expandable, as well, but the "2021 M1" iMac models are impressively fast and sold for a relatively modest price.

In the US, site sponsor Adorama sells new iMac models with free shipping. Other World Computing sells used and refurb iMac models at bargain prices with free shipping, as well. Finally, if you need to sell an iMac, A+ BBB-rated Cash for Your Mac will buy your older iMac with an instant quote and prompt payment.

In the UK, site sponsor Hoxton Macs sells used iMac models with a one-year warranty and free next day delivery throughout the UK. Delivery across Europe also is available starting at just £9.99 for two-day delivery to France and Germany.