Mac Studio M5 Ultra, 96GB vs 256GB for local AI
The Mac Studio M5 Ultra, 256GB holds 38 of the 39 open models here, and the Mac Studio M5 Ultra, 96GB holds 29. The Mac Studio M5 Ultra, 96GB costs $5,300 less. On Qwen3.8 27B, the strongest model both hold, they run at much the same speed: 48 and 48 tok/s, both estimated from memory bandwidth. The Mac Studio M5 Ultra, 96GB pays for itself sooner, in 68 years against 965 years at 500k tokens a day, though that is each machine on its own strongest model rather than on the same one.
| Mac Studio M5 Ultra, 96GB | Mac Studio M5 Ultra, 256GB | |
|---|---|---|
| Price | $5,499 | $10,799 |
| Memory | 96 GB | 256 GB |
| Usable by the GPU | 72 GB | 192 GB |
| Memory bandwidth | 1200 GB/s | 1200 GB/s |
| Power under load | 270 Wstand-in | 270 Wstand-in |
| Models that fit | 29 | 38 |
| Best model it runs | Qwen3.8 27B | GLM-5.3-Flash |
| Speed on that model | 48 tok/s estimatedQwen3.8 27B | 32 tok/s estimatedGLM-5.3-Flash |
| Pay-back on that model | Pays back in 68 years | Pays back in 965 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 what the row shows is one borrowed figure printed twice. 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 Mac Studio M5 Ultra, 96GB · or the Mac Studio M5 Ultra, 256GB
The step up is a different chip, not just more memory
Mac Studio M5 Ultra is one name for two machines. The data lists the 96GB as 30-core CPU / 64-core GPU and the 256GB as 36-core CPU / 80-core GPU. The step adds 16 GPU cores to the graphics part, 80 against 64. That is why this pair is not one of the site's memory-size comparisons: those hold the silicon equal so the memory is the whole of the difference, and Apple cut both to reach the $5,499.
The bigger graphics part is not what sets the speeds on this page. Writing a token means reading the whole model out of memory, and both chips read it at 1200 GB/s, so the figures follow the memory rather than the chip. What the extra GPU cores do is read a long prompt before the first token comes back, and that is not something this site measures or prices. The 256GB box holds 38 of the 39 models the calculator counts against 29 on the 96GB. Price the Mac Studio M5 Ultra, 96GB on its own before paying for the step: if the models you want fit the cheaper box, the chip above it is not buying you tokens.
Side by side on Qwen3.8 27B
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. Qwen3.8 27B is the strongest model both machines hold, so this is the pair running the same work.
| Mac Studio M5 Ultra, 96GB | Mac Studio M5 Ultra, 256GB | |
|---|---|---|
| Speed | 48 tok/s estimated | 48 tok/s estimated |
| Pay-back | Pays back in 68 years | Pays back in 134 years |
Run Qwen3.8 27B on the Mac Studio M5 Ultra, 96GB · or on the Mac Studio M5 Ultra, 256GB
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 Mac Studio M5 Ultra, 96GB 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 use | Mac Studio M5 Ultra, 96GB | Mac Studio M5 Ultra, 256GB |
|---|---|---|
| 50ka few chats a day | 685 years | 1,345 years |
| 200klight assistant use | 171 years | 336 years |
| 1Ma moderate coding-assistant day | 34 years | 67 years |
| 4Mheavy coding with an agent | 8.6 years | 17 years |
| 20Magents running most of the day | 21 months | 3.4 years |
Run the Mac Studio M5 Ultra, 96GB at 20M tokens a day · or the Mac Studio M5 Ultra, 256GB
What the extra memory buys
The Mac Studio M5 Ultra, 256GB holds 9 models the Mac Studio M5 Ultra, 96GB cannot at 32k of context. The strongest of them are what the difference in memory actually buys.
| Model | Weights | Needs at 32k | On the Mac Studio M5 Ultra, 256GB |
|---|---|---|---|
| GLM-5.3-FlashSonnet-class | 189 GB | 190 GB | 32 tok/s estimated |
| Qwen3.8 Flash NextSonnet-class | 120 GB | 121 GB | 74 tok/s estimated |
| DeepSeek V4-FlashSonnet-class | 155 GB | 155 GB | 49 tok/s estimated |
| Inkling SmallHaiku-class | 163 GB | 164 GB | 43 tok/s estimated |
| Ling 3.0 flashHaiku-class | 78 GB | 82 GB | 52 tok/s estimated |
| MiniMax M2.7Haiku-class | 140 GB | 149 GB | 25 tok/s estimated |
3 more, on the Mac Studio M5 Ultra, 256GB page.
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 Mac Studio M5 Ultra, 96GB runs · everything the Mac Studio M5 Ultra, 256GB runs · every other match-up · the quickest pay-back at each level of use · every model against the frontier