GPT-6.1 Terra vs Claude Sonnet 5.5
Official OpenAI and Anthropic API prices and LMArena scores, checked 2026-10-28. Add up to 2 more models to compare 4.
GPT-6.1 Terra costs less; Claude Sonnet 5.5 wins more LMArena tasks.
GPT-6.1 Terra is 2x cheaper on input and output. Claude Sonnet 5.5 scores 36 points higher for coding. Across 1 shared LMArena task, Claude Sonnet 5.5 leads 1 to 0. A medium month (20M input + 5M output tokens) costs $45 on GPT-6.1 Terra and $90 on Claude Sonnet 5.5.
- Pick GPT-6.1 Terra if you want the lower bill ($45 vs $90 for a medium month) or you reuse long prompts (cached input $0.05 vs $0.10).
- Pick Claude Sonnet 5.5 if you care most about coding (+36).
Medium: 20M input + 5M output tokens a month at list price (short-context rate, no caching or batch discounts).
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 Sonnet 5.5 |
|---|---|---|
| Price per 1M tokens | ||
| Input | $1 | $2 |
| Cached input | $0.05 | $0.10 |
| Output | $5 | $10 |
| Blend 3:1 | $2 | $4 |
| Sample month, medium | $45 | $90 |
| Context | ||
| Context window | 1.05M tokens | 1M tokens |
| Quality (LMArena, out of 100) | ||
| Coding | 49/100 #10 of 24 | 85/100 #3 of 24 |
| Chat | Not ranked | 21/100 #13 of 26 |
| Creative writing | Not ranked | 28/100 #10 of 26 |
| Roleplay and characters | Not ranked | 0/100 #15 of 26 |
| Reasoning and math | Not ranked | 48/100 #8 of 26 |
| Vision | Not ranked | 22/100 #15 of 22 |
| Long documents | Not ranked | Not ranked |
| Cheap bulk and agents | Not ranked | 83/100 #2 of 22 |
| Details | ||
| Provider | OpenAI | Anthropic |
| API model id | gpt-6.1-terra | claude-sonnet-5.5 |
| Notes | New Oct 26, 2026. Prompts up to 272K. Longer prompts cost $2 in, $7.50 out. | 5-minute cache writes $2.50. |
| Sources | ||
| Last checked | 2026-10-28 | 2026-10-28 |
| Official pricing | OpenAI pricing | Anthropic pricing |
Plans from data checked hourly against each vendor's official pricing page. Vendors state limits in different units, so we quote them as published. Team and enterprise plans are per seat.
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 Sonnet 5.5 #3 of 24 (85/100)
- Chat (Text Arena): GPT-6.1 Terra not ranked, Claude Sonnet 5.5 #13 of 26 (21/100)
- Creative writing (Text Arena creative writing): GPT-6.1 Terra not ranked, Claude Sonnet 5.5 #10 of 26 (28/100)
- Roleplay and characters (Text Arena multi-turn): GPT-6.1 Terra not ranked, Claude Sonnet 5.5 #15 of 26 (0/100)
- Reasoning and math (Text Arena math): GPT-6.1 Terra not ranked, Claude Sonnet 5.5 #8 of 26 (48/100)
- Vision (Vision Arena): GPT-6.1 Terra not ranked, Claude Sonnet 5.5 #15 of 22 (22/100)
- Long documents (Document Arena): GPT-6.1 Terra not ranked, Claude Sonnet 5.5 not ranked
- Cheap bulk and agents (Agent Arena): GPT-6.1 Terra not ranked, Claude Sonnet 5.5 #2 of 22 (83/100)
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 Sonnet 5.5 lists $2 input, $10 output, $0.10 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 Sonnet 5.5: 5-minute cache writes $2.50.
Sample monthly bill at list price, no caching: Light (2M input + 0.5M output tokens): $4.50 vs $9. Medium (20M input + 5M output tokens): $45 vs $90. Heavy (200M input + 50M output tokens): $450 vs $900.
FAQ
Is GPT-6.1 Terra cheaper than Claude Sonnet 5.5?
GPT-6.1 Terra costs $1 input and $5 output per 1M tokens; Claude Sonnet 5.5 costs $2 and $10. For a medium month (20M input + 5M output tokens) GPT-6.1 Terra is cheaper: $45 vs $90.
Which is better for coding, GPT-6.1 Terra or Claude Sonnet 5.5?
On LMArena's Code Arena GPT-6.1 Terra scores 49/100 (#10 of 24) and Claude Sonnet 5.5 85/100 (#3 of 24), so Claude Sonnet 5.5 is ahead by 36 points.
Which has the bigger context window?
GPT-6.1 Terra: 1.05M tokens. Claude Sonnet 5.5: 1M tokens. Long prompts can cost more; see the pricing notes above.
How much do GPT-6.1 Terra and Claude Sonnet 5.5 cost per month?
Light (2M input + 0.5M output tokens): $4.50 vs $9. Medium (20M input + 5M output tokens): $45 vs $90. Heavy (200M input + 50M output tokens): $450 vs $900. 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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