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Home / Compare / AI models / GPT-6.1 Terra vs Claude Opus 5.5

GPT-6.1 Terra vs Claude Opus 5.5

Official OpenAI and Anthropic API prices and LMArena scores, checked 2026-10-28. Add up to 2 more models to compare 4.

Verdict

GPT-6.1 Terra costs less; Claude Opus 5.5 wins more LMArena tasks.

GPT-6.1 Terra is 4x cheaper on input and output. Claude Opus 5.5 scores 51 points higher for coding. Across 1 shared LMArena task, Claude Opus 5.5 leads 1 to 0. A medium month (20M input + 5M output tokens) costs $45 on GPT-6.1 Terra and $180 on Claude Opus 5.5.

  • Pick GPT-6.1 Terra if you want the lower bill ($45 vs $180 for a medium month) or you reuse long prompts (cached input $0.05 vs $0.20).
  • Pick Claude Opus 5.5 if you care most about coding (+51).
Sample month

Medium: 20M input + 5M output tokens a month at list price (short-context rate, no caching or batch discounts).

GPT-6.1 TerravsClaude Opus 5.5
Price per 1M tokens
Input$1 (better)$4
Cached input$0.05 (better)$0.20
Output$5 (better)$20
Sample month, medium$45 (better)$180
Context
Context window1.05M (better)1M
Quality (LMArena relative score, out of 100)
Coding49100 (better)
Chatn/a83
Creative writingn/a100
Roleplay and charactersn/a41
Reasoning and mathn/a67
Visionn/a84
Long documentsn/an/a
Cheap bulk and agentsn/a100

Marked side is better: lower for prices, higher for context and scores. Bars are scaled to the larger of the two.

Spec
GPT-6.1 Terra
Claude Opus 5.5
Price per 1M tokens
Input$1$4
Cached input$0.05$0.20
Output$5$20
Blend 3:1$2$8
Sample month, medium$45$180
Context
Context window1.05M tokens1M tokens
Quality (LMArena, out of 100)
Coding49/100 #10 of 24100/100 #1 of 24
ChatNot ranked83/100 #2 of 26
Creative writingNot ranked100/100 #1 of 26
Roleplay and charactersNot ranked41/100 #4 of 26
Reasoning and mathNot ranked67/100 #6 of 26
VisionNot ranked84/100 #3 of 22
Long documentsNot rankedNot ranked
Cheap bulk and agentsNot ranked100/100 #1 of 22
Details
ProviderOpenAIAnthropic
API model idgpt-6.1-terraclaude-opus-5.5
NotesNew Oct 26, 2026. Prompts up to 272K. Longer prompts cost $2 in, $7.50 out.5-minute cache writes $5.
Sources
Last checked2026-10-282026-10-28
Official pricingOpenAI pricingAnthropic pricing

API prices in USD per 1M tokens from each provider's official pricing page. Blend 3:1 = (3 x input + output) / 4. Sample month = stated input and output tokens at the list price, no caching. Quality: relative score out of 100 on each LMArena leaderboard (100 = top model we price on that board, n/a = not ranked there), data licensed CC BY 4.0. See how we pick.

Where each one ranks on LMArena

Relative score out of 100 on each leaderboard (100 = the top model we price there), with the rank among the models from our API price table that appear on that board.

  • Coding (Code Arena): GPT-6.1 Terra #10 of 24 (49/100), Claude Opus 5.5 #1 of 24 (100/100)
  • Chat (Text Arena): GPT-6.1 Terra not ranked, Claude Opus 5.5 #2 of 26 (83/100)
  • Creative writing (Text Arena creative writing): GPT-6.1 Terra not ranked, Claude Opus 5.5 #1 of 26 (100/100)
  • Roleplay and characters (Text Arena multi-turn): GPT-6.1 Terra not ranked, Claude Opus 5.5 #4 of 26 (41/100)
  • Reasoning and math (Text Arena math): GPT-6.1 Terra not ranked, Claude Opus 5.5 #6 of 26 (67/100)
  • Vision (Vision Arena): GPT-6.1 Terra not ranked, Claude Opus 5.5 #3 of 22 (84/100)
  • Long documents (Document Arena): GPT-6.1 Terra not ranked, Claude Opus 5.5 not ranked
  • Cheap bulk and agents (Agent Arena): GPT-6.1 Terra not ranked, Claude Opus 5.5 #1 of 22 (100/100)

Pricing details from the official pages

GPT-6.1 Terra lists $1 input, $5 output, $0.05 cached input per 1M tokens on OpenAI pricing. Claude Opus 5.5 lists $4 input, $20 output, $0.20 cached input per 1M tokens on Anthropic pricing. Prices checked 2026-10-28.

  • GPT-6.1 Terra: New Oct 26, 2026. Prompts up to 272K. Longer prompts cost $2 in, $7.50 out.
  • Claude Opus 5.5: 5-minute cache writes $5.

Sample monthly bill at list price, no caching: Light (2M input + 0.5M output tokens): $4.50 vs $18. Medium (20M input + 5M output tokens): $45 vs $180. Heavy (200M input + 50M output tokens): $450 vs $1,800.

FAQ

Is GPT-6.1 Terra cheaper than Claude Opus 5.5?

GPT-6.1 Terra costs $1 input and $5 output per 1M tokens; Claude Opus 5.5 costs $4 and $20. For a medium month (20M input + 5M output tokens) GPT-6.1 Terra is cheaper: $45 vs $180.

Which is better for coding, GPT-6.1 Terra or Claude Opus 5.5?

On LMArena's Code Arena GPT-6.1 Terra scores 49/100 (#10 of 24) and Claude Opus 5.5 100/100 (#1 of 24), so Claude Opus 5.5 is ahead by 51 points.

Which has the bigger context window?

GPT-6.1 Terra: 1.05M tokens. Claude Opus 5.5: 1M tokens. Long prompts can cost more; see the pricing notes above.

How much do GPT-6.1 Terra and Claude Opus 5.5 cost per month?

Light (2M input + 0.5M output tokens): $4.50 vs $18. Medium (20M input + 5M output tokens): $45 vs $180. Heavy (200M input + 50M output tokens): $450 vs $1,800. Pick your own token counts in the plan vs API calculator.

Where do these numbers come from?

Prices come from each provider's official pricing page, checked daily. Quality is the relative score on the LMArena leaderboard dataset, licensed CC BY 4.0. Where a model is not ranked we show n/a.

Sources

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