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ModelCap

Model decision surface

Compare AI models

Start with Claude Opus 5.5 and GPT-5.6 Terra, or choose any two current ranked language models. Compare capability evidence, price, context, provider availability, and weight access without pretending one field decides every use case.

Current public data

Claude Opus 5.5 vs GPT-5.6 Terra

Live dataset updated 9/22/2026, 10:37:09 PM UTC

Open 1200×630 evidence receipt
Factual comparison of Claude Opus 5.5 and GPT-5.6 Terra
Field
ModelCap position#1#21
Index score98.679.7
EvidenceMeasured2 public benchmark observations across 2 boardsMeasured6 public benchmark observations across 6 boards
Input / 1M$4.00$2.00
Output / 1M$20.00$12.00
Pricing statusfreshfresh
Context1M1M
Providers53
Weight accessAPI onlyAPI only

Decision facts

  • Claude Opus 5.5 is #1; GPT-5.6 Terra is #21 on the same current language board.
  • Index scores are 98.6 for Claude Opus 5.5 and 79.7 for GPT-5.6 Terra. Their published uncertainty intervals overlap, so the rank difference alone does not establish a reliable capability advantage for your workload.
  • Both positions use Measured evidence.
  • Listed output price per 1M tokens is $20.00 for Claude Opus 5.5 and $12.00 for GPT-5.6 Terra. For 1,000 requests with 2,000 input and 500 output tokens each (2M input + 0.5M output), the listed-rate estimate is $18.00 for Claude Opus 5.5 versus $10.00 for GPT-5.6 Terra. GPT-5.6 Terra costs 44.4% less in this scenario. This excludes caching, batch discounts, prompt-length tiers, tool charges and retries; verify the selected endpoint before budgeting.
  • Published context is 1,000,000 tokens for Claude Opus 5.5 and 1,050,000 for GPT-5.6 Terra.
  • ModelCap currently lists 5 providers for Claude Opus 5.5 and 3 for GPT-5.6 Terra.

These are separate published fields, not a synthetic winner. ModelCap does not collapse price, access, context, and capability evidence into a hidden recommendation score.

Each comparison page is a permanent, shareable URL with the same live figures as this tool: ModelCap Index position, API pricing, context window, provider count, weight access and every shared benchmark board.