Claude Opus 4.8 vs GPT-5.5 Instant
Pricing, benchmarks, and use case comparison
Quick take
- •Claude Opus 4.8 is meaningfully stronger at coding (96 vs 78 on our capability index).
- •GPT-5.5 Instant is meaningfully stronger at speed (92 vs 68).
Specs comparison
| Claude Opus 4.8 | GPT-5.5 Instant | |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Type | Closed source | Closed source |
| Context window | 1M | ✓1050000 |
| Input / 1M tokens | $5.00 | 5.00 |
| Output / 1M tokens | $25.00 | 30.00 |
| Release date | 2026-05 | 2026-05 |
Benchmarks
| Benchmark | Claude Opus 4.8 | GPT-5.5 Instant |
|---|---|---|
| SWE-bench Verified | 88.6% | - |
| SWE-bench Pro | 69.2% | - |
| Terminal-Bench 2.1 | 74.6% | - |
| GPQA Diamond | 93.6% | - |
| Artificial Analysis Intelligence Index | 61.4 | - |
| AIME 2025 | - | 81.2 |
| Terminal-Bench 2.0 | - | 82.7 |
| FrontierMath Tier 1–3 | - | 51.7 |
Scores sourced from official provider release posts and independent benchmark aggregators.
Which should you choose?
Choose Claude Opus 4.8 if...
- →You need top-tier autonomous coding and multi-step agentic reliability
- →You run long-horizon agent traces that previously derailed after compaction
- →You want enterprise-grade reasoning with 1M context and 128k output
- →You need throughput and are willing to pay fast-mode premium for 2.5x speed
Choose GPT-5.5 Instant if...
- →Interactive chat and everyday assistant tasks where responsiveness matters most
- →High-volume, latency-sensitive workloads that do not need deep reasoning
- →General questions, drafting, and summarization at speed