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OpenAI GPT-5.5 VS OpenAI GPT-5.6 Sol

✍️ Analysis by:the whichllmmodel Editorial Team|📅 Updated: June 2026

Decision Recommendation

👑 Editorial Verdict: GPT-5.6 Sol strictly dominates GPT-5.5 across all compared dimensions. It is not only more cost-effective (blended cost of $11.25 vs $11.25 per 1M tokens) but also delivers superior coding accuracy (64.6% vs 58.6% on SWE-bench). Unless you have platform lock-in, GPT-5.6 Sol is the clear and optimal choice for all development workloads.
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Model Specs

GPT-5.5

Benchmarks & Scores

Coding (swe-bench-pro)
58.6%

excellent at multi-file repositories, autonomous agents, and industrial codebases

Reasoning (gpqa-diamond)
93.6%

graduate-level science QA

Cost & Performance

Cost (per 1M tokens)
$11.25Input: $5.00 | Output: $30.00
Context Window
1.05M tokens
Model Specs

GPT-5.6 Sol

Benchmarks & Scores

Coding (swe-bench-pro)Winner (+6.0%)
64.6%

excellent at multi-file repositories, autonomous agents, and industrial codebases

Reasoning (gpqa-diamond)Winner (+1.0%)
94.6%

graduate-level science QA

Cost & Performance

Cost (per 1M tokens)
$11.25Input: $5.00 | Output: $30.00
Context Window
1.05M tokens

Frequently Asked Questions about GPT-5.5 vs GPT-5.6 Sol comparison

Both GPT-5.5 and GPT-5.6 Sol cost the same, with a blended cost of $11.25 per 1 million tokens.

GPT-5.6 Sol is better for coding tasks on this benchmark. It scores 64.6% on swe-bench-pro (excellent at multi-file repositories, autonomous agents, and industrial codebases) compared to GPT-5.5 which scores 58.6%.