Mac Studio M5 Max 128 GB vs Mac Studio M5 Ultra 256 GB
Verdict
- throughputThe Mac Studio M5 Ultra 256 GB delivers approximately 65% higher aggregate decode throughput across the 8 models both machines can run (geometric mean of the per-model ratios).
- capacityBoth machines run all 8 compared models, so this is a pure speed and cost decision rather than a capability one.
- costAt 8 hours a day, the Mac Studio M5 Max 128 GB has approximately 50% lower total monthly cost (€45 against €90), for a C corporation in United States (federal).
- powerThe Mac Studio M5 Ultra 256 GB draws 215 W under load against 122 W for the Mac Studio M5 Max 128 GB — a 1.8× difference that shows up in the electricity line and in how loud and hot the room gets.
- evidenceEvery throughput figure in this comparison is estimated. Treat the ranking as indicative and the margins as unreliable.
- recommendationThere is no single answer: the Mac Studio M5 Ultra 256 GB is faster, the Mac Studio M5 Max 128 GB is cheaper to own, and the Mac Studio M5 Max 128 GB gives more throughput per euro of purchase price. Pick on whichever constraint actually binds you — interactive latency, monthly budget, or capacity headroom for larger models later.
Every statement above is generated from the calculations on this page by fixed rules — no prose is written for individual comparisons. If the numbers change, the verdict changes with them.
Hardware
| Mac Studio M5 Max 128 GB | Mac Studio M5 Ultra 256 GB | |
|---|---|---|
| Price (NL, incl. VAT) | €4.323 | €8.647 |
| Memory | 128 GB | 256 GB |
| Memory bandwidth | 614 GB/s | 1,200 GB/s |
| Achieved bandwidth | 538 GB/s (88%) | 1,052 GB/s (88%) |
| Nominal power | 175 W | 300 W |
| Measured load power | 122 W | 215 W |
| Idle power | 8 W | 13 W |
| Architecture | unified memory | unified memory |
Model performance8 models run on both
Qwen3.8 Flash NextQwen3.5 122B-A10Bgpt-oss-120bQwen3-Coder 30B-A3BQwen3 30B-A3BGemma 4 26B-A4Bgpt-oss-20bLlama 3.3 70B
| Model | Mac Studio M5 Max 128 GB | Mac Studio M5 Ultra 256 GB | Winner |
|---|---|---|---|
| Qwen3.8 Flash Next 180B (6B active) | ~97.9–141 t/s MLX 4-bit | ~162–233 t/s Q4_K_M | Mac Studio M5 Ultra 256 GB +40% |
| Qwen3.5 122B-A10B 125.086B (10B active) | ~57.5–82.8 t/s Q4_K_M | ~63.6–91.6 t/s Q8_0 | Tie (10%) |
| gpt-oss-120b 116.829B (5.1B active) | ~118–170 t/s MXFP4 | ~203–293 t/s MXFP4 | Mac Studio M5 Ultra 256 GB +42% |
| Qwen3-Coder 30B-A3B 30.532B (3.3B active) | ~94.6–136 t/s Q8_0 | ~167–240 t/s Q8_0 | Mac Studio M5 Ultra 256 GB +43% |
| Qwen3 30B-A3B 30.532B (3.3B active) | ~94.6–136 t/s Q8_0 | ~167–240 t/s Q8_0 | Mac Studio M5 Ultra 256 GB +43% |
| Gemma 4 26B-A4B 25.806B (3.8B active) | ~83.4–120 t/s Q8_0 | ~149–214 t/s Q8_0 | Mac Studio M5 Ultra 256 GB +44% |
| gpt-oss-20b 20.915B (3.6B active) | ~158–228 t/s MXFP4 | ~261–376 t/s MXFP4 | Mac Studio M5 Ultra 256 GB +39% |
| Llama 3.3 70B 70.554B | ~5.8–8.4 t/s Q8_0 | ~11.3–16.3 t/s Q8_0 | Mac Studio M5 Ultra 256 GB +48% |
Differences under 10% are reported as a tie: they are smaller than the spread between published benchmarks of the same configuration, so calling a winner would be false precision. Rows where a model fits on only one machine are decided by capacity, not speed.
Economics — United States (federal), C corporation, 8h/day
| Mac Studio M5 Max 128 GB | Mac Studio M5 Ultra 256 GB | |
|---|---|---|
| Purchase price estimate | $4,323 | $8,647 |
| Reclaimable VAT | $0 | $0 |
| Net cash at purchase | $4,323 | $8,647 |
| Monthly depreciation | $50.44 | $100.88 |
| Monthly electricity | $0.76 (5 kWh) | $1.32 (9 kWh) |
| Tax programme | §179 100.0% | §179 100.0% |
| Tax-programme benefit | $908 | $1,816 |
| Monthly economic cost | $45.27 | $90.39 |
| Total over 5 years | $2,716 | $5,424 |
Tax assumptions last verified 2026-09-07. Federal planning estimate only, not tax advice. State and local income tax, sales/use tax and incentives are excluded. It assumes 100% business use, a Section 179 election, enough business income to use it, and that the full annual limit remains available.