Mistral Small 4 119B-A6.5B on Mac Studio M5 Max 64 GB

119.401B (6.5B active) on 64 GB at 614 GB/s. Hardware details · Model details

No calculated fit. Mistral Small 4 119B-A6.5B does not fit under standard overhead assumptions at MLX 4-bit: the model calculates 68.2 GB required against 54.4 GB usable.
CompatibilityDoes not fit
Calculated fit
No
Calculated Requires more than 97% of usable memory. Needs a smaller quantization or more memory.
Smallest catalogued quantization
MLX 4-bit
Calculated mlx
Memory required
68.2 GB
Calculated of 54.4 GB usable — 125%
Max practical context
0
Calculated model supports 256K

Memory budget at 8K context

Model weights
65.1 GB Calculated
KV cache
0.2 GB Calculated
Runtime overhead
3.0 GB Estimated
Total required
68.2 GB Calculated
Headroom
-13.8 GB Calculated
No quantization in our catalogue fits this machine.
Unified memory: weights, KV cache and the OS share the same 64 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 119.401B parameters must be resident in memory even though only ~6.5B are active per token. Memory follows total parameters; speed follows active parameters.
Performance

Estimated performance · recommended MLX 4-bit

Decode, prefill and TTFT below are estimates for MLX 4-bit. We do not have a comparable MLX 4-bit measurement on this machine.

Estimated decode
Estimated MLX 4-bit; calculated range
Estimated prefill
Estimated MLX 4-bit; calculated range
Estimated TTFT at 8K
~7.6–15.8 s
Estimated MLX 4-bit; calculated range
Hardware load reference
118 W
Measured machine-level load; not this model run
No throughput figures for this configuration. We do not estimate performance for a model that cannot load.
How the estimate is calculated
  1. Decode: reading 6.5B active parameters at 4.50 bits/weight takes 6.80 ms at 614 GB/s x 88% achieved efficiency.
  2. MoE routing penalty of 15% applied: expert gathers are less bandwidth-efficient than a dense sweep.
  3. Prefill: 120 TFLOPS (FP16) x 1.69 calibrated against measured prefill on this platform x 22% assumed model-FLOPs utilisation, divided by 2 x 27.9B parameters per token.
  4. Prefill uses 27.9B effective parameters, not the 6.5B 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
QuantizationResidentDiskTotal neededUtilisationFitMax context
MLX 4-bitsmallest listed65.1 GB65.1 GB68.2 GB125%Does not fit0
Q4_K_M69.4 GB69.4 GB72.7 GB134%Does not fit0
Q5_K_M81.5 GB81.5 GB85.1 GB156%Does not fit0
Q8_0120.5 GB120.5 GB125.3 GB230%Does not fit0
BF16222.4 GB222.4 GB230.2 GB423%Does not fit0
Cost of running Mistral Small 4 119B-A6.5B on this machineUnited States (federal) · C corporation · 8h/day
Monthly economic cost
$37
Calculated after tax
Codex/Claude Code
$100/mo
≈ $100/mo · local is $63 less
Net cash at purchase
$3,512
Calculated VAT not reclaimable
Total over 5 years
$2,213
Calculated after tax, after resale
Cost per USD/1M tokens
Calculated

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: $3,512 in United States (federal), tax/VAT excluded · estimated · Apple Store NL (converted catalogue estimate). This is the localized purchase input; the after-tax economic cost is calculated separately below.

Monthly breakdown

Depreciation
2,459 over 5 years, straight-line to a 1,054 residual
$40.98
Electricity
5.3 kWh/month at 0.140/kWh
$0.74
Cost of capital
4.0%/yr on 2,283 average capital employed
$7.61
Monthly cost before tax$49.33
Electricity tax shield
Running costs are deductible business expenses
−$0.16
First-year expensing
§179 (100.0%)
−$12.29
Monthly economic cost after tax$36.88

Three different numbers, deliberately

Cash cost
$3,512
Money that leaves the bank account on day one, net of reclaimable VAT.
Accounting depreciation
$40.98/month
$2,459 written down over 5 years to a $1,054 residual.
After-tax economic cost
$36.88/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
$1,054 (30%) Assumption
Extrapolated from the three-year curve.
Electricity
$0.140/kWh Assumption
Average power draw
30 W Calculated
Load 118 W for 20% of powered hours, idle 8 W for the rest — a machine that is on is not generating tokens the whole time.
Investment allowances
§179 100.0% Official spec
Worth $738 in total — first-year expensing that replaces later tax depreciation.
Cost of capital
$7.61/month Assumption
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.