Claude Sonnet 5 vs GPT-5.5 Instant
Pricing, benchmarks, and use case comparison
Quick take
- •Claude Sonnet 5 is meaningfully stronger at cost efficiency (85 vs 70 on our capability index).
- •GPT-5.5 Instant is meaningfully stronger at speed (92 vs 82).
- •Claude Sonnet 5 is 40% cheaper on input tokens, which compounds fast on high-volume or agentic workloads.
Specs comparison
| Claude Sonnet 5 | GPT-5.5 Instant | |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Type | Closed source | Closed source |
| Context window | 1M | ✓1050000 |
| Input / 1M tokens | ✓$3.00 | 5.00 |
| Output / 1M tokens | $15.00 | 30.00 |
| Release date | 2026-06 | 2026-05 |
Benchmarks
| Benchmark | Claude Sonnet 5 | GPT-5.5 Instant |
|---|---|---|
| SWE-bench Verified | ~85.2% | - |
| Terminal-Bench 2.1 | 80.4% | - |
| SWE-bench Pro | 63.2% | - |
| OSWorld-Verified | 81.2% | - |
| 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 Sonnet 5 if...
- →You want frontier-adjacent agentic coding but need better cost-efficiency than Opus
- →You are running high-volume agent loops and want strong reasoning per dollar
- →You are already on Sonnet 4.6 and want a same-price capability upgrade
- →You need a 1M context window with fast latency
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