Mac Studio M3 Ultra vs M5 Ultra, 256GB for local AI

Both hold 38 of the 39 open models here. The Mac Studio M3 Ultra, 256GB costs $3,700 less. On GLM-5.3-Flash, the strongest model both hold, the Mac Studio M5 Ultra, 256GB is about 1.5× faster: 32 tok/s against 22, both estimated from memory bandwidth. The Mac Studio M3 Ultra, 256GB pays for itself sooner, in 781 years against 965 years at 500k tokens a day. The Mac Studio M3 Ultra, 256GB is the previous generation, so every figure here for it is priced at what it launched at rather than at a price you can pay today.

Run the numbers on the Mac Studio M3 Ultra, 256GB · or the Mac Studio M5 Ultra, 256GB

What the newer chip buys

These are the same machine a generation apart, in the same case and at the same memory size, so this is the upgrade question rather than a choice between two things on sale. What separates them is bandwidth: the M5 Ultra reads its memory at 1200 GB/s where the M3 Ultra reads it at 819. Decoding reads the whole model out of memory for every token it writes, so that is the figure the speeds in the table follow. The M5 Ultra here is listed as 36-core CPU / 80-core GPU, against the M3 Ultra's 32-core CPU / 80-core GPU.

The two power figures are equal for a reason that is not about either machine: Apple has not published one for the M5 Ultra, so the data stands the M3 Ultra's published 270 W in for it and this page prices the electricity into both columns from that. Read it as a placeholder, not as a finding that the newer chip draws the same.

Apple stopped selling the Mac Studio M3 Ultra, 256GB on 25 August 2026, so the $7,099 above is the price it launched at, and every figure on this page for it is priced at that. A used or refurbished one costs whatever it costs, and pay-back follows the price rather than the machine. Open the calculator on the Mac Studio M3 Ultra, 256GB and put in what you would actually pay; the years move with it. Its own page has what the data records about buying one now.

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 GLM-5.3-Flash, the strongest model both hold, at the five levels of use the calculator names. The Mac Studio M3 Ultra, 256GB pays back sooner at every level of use, so this is not a choice that turns on how hard you work it.

Run the Mac Studio M3 Ultra, 256GB at 20M tokens a day · or the Mac Studio M5 Ultra, 256GB

Memory is not what separates them

Every model on this list that fits one machine fits the other, and not only at 32k of context: across all 39 models the calculator counts, at every context from 4k to 256k, there is no model one holds and the other does not. Both leave 192 GB to the GPU. So the choice between them is speed, price and power, not what they can hold.

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. Graphics cards are priced as the card alone, so add the PC around one before comparing it with a complete computer. Change any of it in the calculator.

More head to head: everything the Mac Studio M3 Ultra, 256GB 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