GPT-5.6 Sol vs Grok 4.6

head-to-head

what do the benchmarks actually say?

On SWE-bench Verified — real, human-validated GitHub issues resolved end-to-end — GPT-5.6 Sol posts 96.2% against 95.6% for Grok 4.6, a 0.6-point gap. Verified is the closest public proxy for "can it fix a real bug in a real repo without help", which is why it anchors our ranking.

A few points either way is real but not decisive: within that band, the agent scaffolding around the model — how it retrieves files, runs tests, and retries — often matters as much as the base model. Treat the gap as a lean, not a verdict.

which is cheaper to run?

Grok 4.6 is the cheaper model: $2 per 1M input tokens ($6 output) versus $5 ($30 output) for GPT-5.6 Sol — roughly 2.5× less on input. Coding workloads are output-heavy — agents write diffs, tests and retries — so weight the output rate more than the input rate when you estimate a monthly bill.

when to pick each

how were these scores verified?

We only print a number once it's confirmed against a primary source or an independent evaluation, and each row on our leaderboard records which kind it is:

• GPT-5.6 Sol: Independent (vals.ai, Jul 14 2026, mini-swe-agent bash-only harness): SWE-bench Verified 96.20% ±0.86 — now the second-highest score on the board. Correction, Jul 25, 2026: this row read "the top score on the board" from Jul 17 until Jul 25, when vals.ai evaluated Claude Opus 5 at 97.00% ±0.76 and took the #1 slot. The 0.8-point gap is ~0.7 sigma and not significant, so the two are a statistical tie, and Sol still leads on the longest tasks (98% vs 90% on the 1-to-4-hour tier). Verified Jul 17, 2026; it had been unranked since Jun 26 because OpenAI published no SWE-bench number of its own, and it still has not. Read the #1 with care: the 1.2-point lead over Claude Fable 5 (95.00% ±0.98) is inside the combined margin of error (~0.9 sigma, not significant), so the two are a statistical tie and we rank Sol first only because it scored higher. Where it does separate is task length — 98% on 1-4 hour tasks vs 93% for Fable 5. OpenAI's own Terminal-Bench 2.1 claim is 88.8% (Sol) / 91.9% (Sol Ultra). No SWE-bench Pro score published. Pricing $5/$30 per 1M.
• Grok 4.6: Independent (vals.ai, benchmark updated 2026-08-12, mini-swe-agent bash-only harness): SWE-bench Verified 95.60% ±0.92. Entered ranked 2026-08-13, one day after launch, and it enters near the top: 4th of the 82 systems vals.ai has run, behind Claude Opus 5 (97.00% ±0.76), DeepSeek V4 Pro 0813 (96.40% ±0.83) and GPT-5.6 Sol (96.20% ±0.86). Read the gap to Claude Fable 5 below it (95.00% ±0.98) as a tie: 0.6 points against a pooled SEM of about 1.34 is well inside the margin of error, and we rank Grok 4.6 higher only because it scored higher. Same against Sol above it, a 0.6-point gap. This is the second time running that xAI shipped a Grok with no SWE-bench Verified number of its own and vals.ai supplied one: Grok 4.5 waited nine days, Grok 4.6 waited one. SpaceXAI still publishes no SWE-bench Verified or SWE-bench Pro figure, so the ranked score here is entirely vals.ai's measurement with no vendor claim to disclose against. What xAI did publish, all vendor-reported on its own table: AA Intelligence Index 61, CursorBench v3.2 69.9%, DeepSWE v1.1 65.9%, FrontierCode v1.1 Extended 61.3%, APEX-Agents 57.5%, APEX-SWE 56.4%, Terminal-Bench v3.0 26%, GDPVal-AA v2 1753, AA-Briefcase 1577, Harvey LAB (Vals) 15.8%. That table's shape still holds and is worth reading against this score: Grok 4.6 takes the best result on the three knowledge-work evals and loses the two hardest agentic-coding ones by wide margins (DeepSWE 65.9% vs Sol's 73%, Terminal-Bench v3.0 26% vs Sol's 34.6%). Terminal-Bench v3.0 is NOT comparable to the 83.3% TB2.1 figure on the Grok 4.5 row: on v3.0 Grok 4.5 scores 15.7% and the whole field tops out near 34%. On cost it is the standout of the top five, $0.78 per test against $1.29 for Opus 5, $1.15 for Sol and $2.05 for Fable 5, though it is also the slowest of them at 604s. Pricing unchanged from Grok 4.5 at $2/$6 per 1M. See /p/grok-4-6-frontier-benchmarks-terminal-bench-gap/.

Full reviewsGPT-5.6 Sol, decodedGrok 4.6, decoded

Ranked on our AI Coding Leaderboard, updated 2026-08-13. Scores are confirmed against primary sources; prices are per 1M input tokens and can change.