OpenAIGPT-5.6 TerraVSxAIGrok 4.20

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

Our Take

If your budget allows, GPT-5.6 Terra is the superior choice here, offering a clear benchmark advantage while carrying only a moderate price premium (1.9x). We recommend choosing Grok 4.20 only if you need to optimize costs for very high-volume pipelines.

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Model Specs

GPT-5.6 Terra

Website

Benchmarks & Scores

Coding (swe-bench-pro)Winner (+11.6%)

63.4%

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

Reasoning (gpqa-diamond)Winner (+2.9%)

92.9%

graduate-level science QA

Cost & Context

Cost (per 1M tokens)

$5.63Input: $2.50 | Output: $15.00

Context WindowLarger

1.05M tokens

Model Specs

Grok 4.20

Website

Benchmarks & Scores

Coding (swe-bench-pro)

51.8%

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

Reasoning (gpqa-diamond)

90%

graduate-level science QA

Cost & Context

Cost (per 1M tokens)1.9x cheaper

$3.00Input: $2.00 | Output: $6.00

Context Window

1.05M tokens

Read our data collection methodology

Frequently Asked Questions about GPT-5.6 Terra vs Grok 4.20

Grok 4.20 is cheaper than GPT-5.6 Terra. Grok 4.20 has a blended cost of $3.00/1M tokens, which is about 1.9x cheaper than GPT-5.6 Terra at $5.63/1M tokens.

GPT-5.6 Terra is better for coding tasks on this benchmark. It scores 63.4% on swe-bench-pro (excellent at multi-file repositories, autonomous agents, and industrial codebases) compared to Grok 4.20 which scores 51.8%.

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