grok-4-1-fast-reasoning vs llama-3.1-8b-instruct

Capability for the money

Not the same tier: grok-4-1-fast-reasoning leads llama-3.1-8b-instruct by 59.4 points on hard reasoning (GPQA Diamond), for 1.4× the price.

1. Following instructions

   extraction, classification, sticking to a format

   IFBench
   grok-4-1-fast-reasoning52.7%

   llama-3.1-8b-instruct28.6%

   grok-4-1-fast-reasoning +24.1

2. Coding

   writing and fixing code

   LiveCodeBench
   grok-4-1-fast-reasoning82.2%

   llama-3.1-8b-instruct11.6%

   grok-4-1-fast-reasoning +70.6

3. Tool use

   multi-step agent work against real tools

   τ²-bench
   grok-4-1-fast-reasoning93.3%

   llama-3.1-8b-instruct16.4%

   grok-4-1-fast-reasoning +76.9

4. Hard reasoning

   graduate-level science and multi-step analysis

   GPQA Diamond
   grok-4-1-fast-reasoning85.3%

   llama-3.1-8b-instruct25.9%

   grok-4-1-fast-reasoning +59.4

Averaged over the benchmarks both models sat, grok-4-1-fast-reasoning returns 285.0 points of pass rate per dollar of blended price against 103.1 — the ratio that decides whether the dearer model earns its rate.

Each figure is a pass rate: the share of that test set the model answered correctly, measured by a third party rather than self-reported by the lab. Rows are different tests of different difficulty, so compare a model against the other model, not one row against the next. And a benchmark is not your workload — it narrows the shortlist, it does not pick for you.