GPT-6.1 Terra beats Claude Sonnet 5.5 on cost in Codex and Claude Code tests

A Linux-server test on October 28, 2026 compared GPT-6.1 Terra in Codex CLI and Claude Sonnet 5.5 in Claude Code on easy and hard task kits. Both solved every task correctly, but a GPT-6.1 Terra round cost $0.0630 versus $0.0847 for Claude Sonnet 5.5 on the easy kit and $0.0689 versus $0.1137 on the hard kit.

• Easy-kit round: $0.0630 for GPT-6.1 Terra vs $0.0847 for Claude Sonnet 5.5
• Hard-kit round: $0.0689 vs $0.1137, a 1.65x difference
• Both passed 9 of 9 hard runs and all easy-kit tasks
• Median round time: 31.5 s vs 47.1 s on the easy kit