Sunk Cost sunkcost.ai Data checked 2026-09-03

MacBook Air M5 (15-inch), 16GB vs MacBook Pro M5 Pro (16-inch), 64GB for local AI

The MacBook Pro M5 Pro (16-inch), 64GB holds 32 of the 48 current models here, and the MacBook Air M5 (15-inch), 16GB holds 12. The MacBook Air M5 (15-inch), 16GB costs $2,500 less. On Gemma 4 12B, the strongest model both hold, the MacBook Pro M5 Pro (16-inch), 64GB is about 2.1× faster: 29 tok/s against 14, both estimated from memory bandwidth. The MacBook Air M5 (15-inch), 16GB pays for itself sooner, in 118 years against 269 years at 500k tokens a day, though that is each machine on its own strongest model rather than on the same one.

MacBook Air M5 (15-inch), 16GBMacBook Pro M5 Pro (16-inch), 64GB
Price$1,499$3,999
Memory16 GB64 GB
Usable by the GPU10.5 GB48 GB
Memory bandwidth153 GB/s307 GB/s
Power under load65 Wstand-in140 Wstand-in
Models that fit1232
Best model it runsGemma 4 12BQwen3.8 27B
Speed on that model14 tok/s estimatedGemma 4 12B12 tok/s estimatedQwen3.8 27B
Pay-back on that modelPays back in 118 yearsPays back in 269 years

Neither power figure above is measured on the machine beside it. Both are stand-ins borrowed from the nearest hardware the data does have, so the gap between them is not a difference between these two machines. Each machine's page names the figure it borrows and why. Every pay-back figure on this page prices its electricity from these numbers.

Run the numbers on the MacBook Air M5 (15-inch), 16GB · or the MacBook Pro M5 Pro (16-inch), 64GB

Jump to: Side by side on Gemma 4 12B · How much use it takes to pay back · What the extra memory buys · The assumptions behind both columns

Side by side on Gemma 4 12B

The table above gives each machine the strongest model it can hold, and those are not the same model, so the two speeds in it are not a race. Gemma 4 12B is the strongest model both machines hold, so this is the pair running the same work.

MacBook Air M5 (15-inch), 16GBMacBook Pro M5 Pro (16-inch), 64GB
Speed14 tok/s estimated29 tok/s estimated
Pay-backPays back in 118 yearsPays back in 318 years

Run Gemma 4 12B on the MacBook Air M5 (15-inch), 16GB · or on the MacBook Pro M5 Pro (16-inch), 64GB

How much use it takes to pay back

Everything above is at 500k tokens a day. Pay-back moves with how much you actually run, so here are both machines on the same model, at the five levels of use the calculator names. The MacBook Air M5 (15-inch), 16GB pays back sooner at every level of use, so this is not a choice that turns on how hard you work it.

A day's useMacBook Air M5 (15-inch), 16GBMacBook Pro M5 Pro (16-inch), 64GB
50ka few chats a day1,177 years3,184 years
200klight assistant use294 years796 years
1Ma moderate coding-assistant day59 years159 years
4Mheavy coding with an agent15 years40 years
20Magents running most of the day3.0 yearsits ceiling8.0 years

On Gemma 4 12B the MacBook Air M5 (15-inch), 16GB generates at most 19.8M tokens a day, so its figure at 20M tokens a day is for the most it can do, not for the whole of what was asked.

Run the MacBook Air M5 (15-inch), 16GB at 20M tokens a day · or the MacBook Pro M5 Pro (16-inch), 64GB

What the extra memory buys

The MacBook Pro M5 Pro (16-inch), 64GB holds 20 models the MacBook Air M5 (15-inch), 16GB cannot at 32k of context. The strongest of them are what the difference in memory actually buys.

ModelWeightsNeeds at 32kOn the MacBook Pro M5 Pro (16-inch), 64GB
Qwen3.8 27BSonnet-class16 GB19 GB12 tok/s estimated
Qwen3.6 27BHaiku-class17 GB19 GB12 tok/s estimated
Nemotron 3.5 Bolt 74B-A9BHaiku-class22 GB22 GB32 tok/s estimated
Qwen3.6 35B-A3BHaiku-class22 GB23 GB37 tok/s estimated
Muse Glimmer 30BHaiku-class17 GB18 GB13 tok/s estimated
Gemma 4 26B-A4BHaiku-class17 GB18 GB27 tok/s estimated

14 more, on the MacBook Pro M5 Pro (16-inch), 64GB page.

The extra memory buys context as well. Of the 12 current models both machines hold at 32k, 7 run to a longer window on the MacBook Pro M5 Pro (16-inch), 64GB: the weights are a fixed size and the KV cache is not, so what the weights leave spare is what a longer context grows into. Ministral 3 8B reaches 256k there against 32k on the MacBook Air M5 (15-inch), 16GB, each the longest window the calculator offers that the machine still holds it at.

The MacBook Air M5 (15-inch), 16GB is also head to head with another computer: Mac mini M5 Pro, 24GB · Mac Studio M5 Max, 128GB · DGX Spark, 128GB · GMKtec EVO-X2, 128GB · MacBook Air M5 (13-inch), 16GB. With a graphics card: RTX PRO 6000 Blackwell, 96GB · Radeon AI PRO R9700, 32GB.

The MacBook Pro M5 Pro (16-inch), 64GB is also head to head with another computer: Mac mini M5 Pro, 24GB · Mac Studio M5 Max, 128GB · DGX Spark, 128GB · GMKtec EVO-X2, 128GB · Beelink GTR9 Pro, 128GB · Minisforum MS-S1 Max, 128GB. With a graphics card: RTX PRO 6000 Blackwell, 96GB · Radeon AI PRO R9700, 32GB. With the same machine at another memory size: 24GB · 48GB.

The assumptions behind both columns

Both columns use the same usage: 500k tokens a day at 15:1 input to output, 32k of context, $0.17 per kWh, and today's API prices held flat. Speeds marked estimated are worked out from memory bandwidth rather than measured, and pay-back scales with them. Change any of it in the calculator.

More head to head: everything the MacBook Air M5 (15-inch), 16GB runs · everything the MacBook Pro M5 Pro (16-inch), 64GB runs · every other match-up · the quickest pay-back at each level of use · every model against the frontier