gpt-5.6-terra vs grok-4-1-fast-reasoning

Capability for the money

Not the same tier: gpt-5.6-terra leads grok-4-1-fast-reasoning by 18.5 points on following instructions (IFBench), for 16.4× the price. They are level on tool use (τ²-bench), so the premium only pays off on following instructions work.

1. Following instructions

   extraction, classification, sticking to a format

   IFBench
   gpt-5.6-terra71.2%

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

   gpt-5.6-terra +18.5

2. Tool use

   multi-step agent work against real tools

   τ²-bench
   gpt-5.6-terra86.3%

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

   grok-4-1-fast-reasoning +7.0

3. Hard reasoning

   graduate-level science and multi-step analysis

   GPQA Diamond
   gpt-5.6-terra92.5%

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

   gpt-5.6-terra +7.2

Averaged over the benchmarks both models sat, grok-4-1-fast-reasoning returns 280.4 points of pass rate per dollar of blended price against 18.5 — 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. No published coding score for one of these models, so that lens is omitted. And a benchmark is not your workload — it narrows the shortlist, it does not pick for you.