GLM-5.3 Flash on Mac Studio M3 Ultra 256 GB
321.323B (18B active) on 256 GB at 819 GB/s. Hardware details · Model details
Yes. GLM-5.3 Flash fits on Mac Studio M3 Ultra 256 GB at the recommended
Q4_K_M configuration, requiring approximately 193.9 GB at 8K context. Practical context capacity is 256K. Expected decode for the recommended configuration is ~35.4–51 t/s. EstimatedCompatibilityFits
Calculated fit
Yes
Calculated Uses 80-90% of usable memory. Works, with limited headroom.
Recommended quantization
Q4_K_M
Calculated gguf
Memory required
193.9 GB
Calculated of 217.6 GB usable — 89%
Max practical context
256K
Calculated model supports 1M
Memory budget at 8K context
Model weights ⓘ
186.9 GB Calculated
KV cache ⓘ
0.4 GB Calculated
Runtime overhead ⓘ
6.6 GB Estimated
Total required
193.9 GB Calculated
Headroom ⓘ
23.7 GB Calculated
Fits with limited headroom (89% of usable memory). A longer context will not leave room for much else.
Unified memory: weights, KV cache and the OS share the same 256 GB pool. We assume 85% is addressable by the GPU, which matches a headless machine with the wired-memory limit raised.
Mixture of experts: all 321.323B parameters must be resident in memory even though only ~18B are active per token. Memory follows total parameters; speed follows active parameters.
Performance
Estimated performance · recommended Q4_K_M
Decode, prefill and TTFT below are estimates for Q4_K_M. We do not have a comparable Q4_K_M measurement on this machine.
Estimated decode
~35.4–51 t/s
Estimated Q4_K_M; calculated range
Estimated prefill
~92–191 t/s
Estimated Q4_K_M; calculated range
Estimated TTFT at 8K
~43.0–89.2 s
Estimated Q4_K_M; calculated range
Hardware load reference
195 W
Measured machine-level load; not this model run
How the estimate is calculated
- Decode: reading 18.0B active parameters at 4.85 bits/weight takes 18.81 ms at 819 GB/s x 71% achieved efficiency.
- MoE routing penalty of 15% applied: expert gathers are less bandwidth-efficient than a dense sweep.
- Prefill: 57 TFLOPS (FP16) x 1.72 calibrated against measured prefill on this platform x 22% assumed model-FLOPs utilisation, divided by 2 x 76.1B parameters per token.
- Prefill uses 76.1B effective parameters, not the 18B active in decode: a batch of hundreds of tokens routes across most of the expert pool.
- MoE decode depends on how well the engine batches expert gathers; real results vary more than for dense models.
- Prefill throughput is highly engine-dependent. Flash attention, batch size and quantized KV all move this number substantially, and for sparse mixture-of-experts models it is the least reliable figure we produce.
- This is a calculated estimate, not a measurement. It assumes a single request, a short prompt, no speculative decoding and a warm model already resident in memory.
Estimator version estimator_v1. Stored with every estimated row so old estimates can be regenerated when the model improves.
Submit a benchmarkSubmissions stay pending until reviewed.
This model at other quantizations on this machine
| Quantization | Resident | Disk | Total needed | Utilisation | Fit | Max context |
|---|---|---|---|---|---|---|
MLX 4-bit | 175.1 GB | 175.1 GB | 181.7 GB | 84% | Fits | 512K |
Q4_K_Mrecommended | 186.9 GB | 186.9 GB | 193.9 GB | 89% | Fits | 256K |
Q5_K_M | 219.2 GB | 219.2 GB | 227.2 GB | 104% | Does not fit | 0 |
Q8_0 | 324.3 GB | 324.3 GB | 335.4 GB | 154% | Does not fit | 0 |
Cost of running GLM-5.3 Flash on this machineUnited States (federal) · C corporation · 8h/day
Monthly economic cost
$60
Calculated after tax
Codex/Claude Code
$100/mo
≈ $100/mo · local is $40 less
Net cash at purchase
$5,674
Calculated VAT not reclaimable
Total over 5 years
$3,575
Calculated after tax, after resale
Cost per USD/1M tokens
$10.88
Calculated 5.5M tokens/month
The $100 comparison uses the Codex Pro 5x / Claude Max 5x plans. A fixed planning conversion is used for USD. This compares monthly spend only: subscriptions have usage limits, local hardware has different capabilities and constraints, and taxes or regional pricing may change the charged amount. Prices checked 7 September 2026.
Purchase-price input: $5,674 in United States (federal), tax/VAT excluded · estimated · Apple Refurbished / used market (converted catalogue estimate). This is the localized purchase input; the after-tax economic cost is calculated separately below.
Monthly breakdown
| Depreciation 3,972 over 5 years, straight-line to a 1,702 residual | $66.20 |
| Electricity 8.6 kWh/month at 0.140/kWh | $1.20 |
| Cost of capital 4.0%/yr on 3,688 average capital employed | $12.29 |
| Monthly cost before tax | $79.69 |
| Electricity tax shield Running costs are deductible business expenses | −$0.25 |
| First-year expensing §179 (100.0%) | −$19.86 |
| Monthly economic cost after tax | $59.58 |
Three different numbers, deliberately
Cash cost
$5,674
Money that leaves the bank account on day one, net of reclaimable VAT.
Accounting depreciation
$66.20/month
$3,972 written down over 5 years to a $1,702 residual.
After-tax economic cost
$59.58/month
Depreciation plus running costs plus cost of capital, less the tax those deductions save. This is the figure to compare between machines.
Assumptions and sources (verified 2026-09-07)
VAT rate
0% Official spec
VAT recoverable
0% Official spec
Federal C-corporation estimate at the flat 21% rate. Pass-through entities should use the sole-proprietor estimate as a rougher proxy.
Effective deduction rate
21.00% Calculated
Headline marginal rate 21.00%.
Depreciation
5 years, straight-line Assumption
Residual value
$1,702 (30%) Assumption
Extrapolated from the three-year curve.
Electricity
$0.140/kWh Assumption
Average power draw
49 W Calculated
Load 195 W for 20% of powered hours, idle 12 W for the rest — a machine that is on is not generating tokens the whole time.
Investment allowances
§179 100.0% Official spec
Worth $1,192 in total — first-year expensing that replaces later tax depreciation.
Cost of capital
$12.29/month Assumption
- VAT rate: No US federal VAT · verified 2026-09-07
- Marginal tax rate: IRS Publication 542 — Corporations · verified 2026-09-07
- VAT recoverable fraction: site assumption · verified 2026-09-07
- Useful life: IRS Publication 946 — How To Depreciate Property · verified 2026-09-07
- Electricity price: Site assumption · verified 2026-09-07
Assumes the machine generates tokens 20% of its 176 powered hours per month. Cost per token scales inversely with this number — halve the utilisation and the cost per token doubles.
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.
Efficiency metrics
Decode per $1,000 spent
7.6 t/s
Calculated purchase price only
Decode per $100/month
72.5 t/s
Calculated after-tax ownership cost
Tokens per joule
0.89
Calculated same as tokens/s per watt
USD per 1M output tokens
$10.88
Calculated at 20% utilisation
Local versus hosted APIs
| Hosted model | USD/1M output | Break-even | API at your volume | Verdict | Comparison type |
|---|---|---|---|---|---|
| Qwen3.8 Flash Alibaba Cloud | $0.42 | 38.7M/mo | $8 | API cheaper | Different model |
| DeepSeek-V4.1 Flash DeepSeek | $0.60 | 33.1M/mo | $10 | API cheaper | Different model |
| DeepSeek-V4 Pro DeepSeek | $1.98 | 8.2M/mo | $40 | API cheaper | Different model |
| DeepSeek V4 Pro (Together) Together AI | $4.40 | 2.8M/mo | $116 | Local cheaper | Different model |
| GLM-5.3 Z.ai | $4.40 | 3.8M/mo | $85 | Local cheaper | Different model |
| Claude Haiku 4.5 Anthropic | $5.00 | 4.6M/mo | $71 | Local cheaper | Different model |
Different-model comparison: the hosted model is not the model you would run locally. Treat this as a workload-quality trade-off, not a direct economic equivalence — the frontier model may complete a task in fewer tokens, or complete tasks the local model cannot. Break-even is the monthly output volume at which API spend equals the $60/month economic cost of owning this machine, assuming 8 input tokens per output token. Hosted prices are published in USD. This table is the canonical US default.
GLM-5.3 Flash on other hardware
| Hardware | Decode | Price | Fit |
|---|---|---|---|
| NVIDIA DGX H200 (8x H200, 1,128 GB) | ~369–531 t/s | $359,430 * | Comfortable |
| Lenovo ThinkStation PX (4x RTX PRO 6000, 384 GB) | ~117–168 t/s | $58,553 * | Comfortable |
| Mac Studio M5 Ultra 256 GB | ~62.1–89.3 t/s | $8,647 * | Fits |
| NVIDIA DGX Station GB300 (748 GB) | ~37.1–53.3 t/s | $90,082 * | Comfortable |
| Mac Studio M5 Ultra 512 GB | ~36.6–52.7 t/s | $11,350 * | Comfortable |
| Mac Studio M3 Ultra 512 GB | ~20.6–29.7 t/s | $8,287 * | Comfortable |
Nearest alternatives to the Mac Studio M3 Ultra 256 GB
GLM-5.3 Flash on Mac Studio M3 Ultra 512 GB512 GBGLM-5.3 Flash on Mac Studio M3 Ultra 96 GB96 GBGLM-5.3 Flash on Mac Studio M5 Ultra 256 GB256 GBGLM-5.3 Flash on Mac Studio M5 Ultra 96 GB96 GBGLM-5.3 Flash on Mac Studio M5 Max 128 GB128 GB
Compare Mac Studio M3 Ultra 256 GB against Mac Studio M3 Ultra 512 GB →
Compare Mac Studio M3 Ultra 256 GB against Mac Studio M3 Ultra 512 GB →