Claude Sonnet 4.6 vs GPT-5.5 Instant
Pricing, benchmarks, and use case comparison
Quick take
- •GPT-5.5 Instant leads on 1 of 1 shared benchmarks, including Terminal-Bench 2.0 (82.7 vs 59.1%).
- •Claude Sonnet 4.6 is meaningfully stronger at cost efficiency (84 vs 70 on our capability index).
- •Claude Sonnet 4.6 is 40% cheaper on input tokens, which compounds fast on high-volume or agentic workloads.
Specs comparison
| Claude Sonnet 4.6 | 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 | 2026-02 | 2026-05 |
Benchmarks
| Benchmark | Claude Sonnet 4.6 | GPT-5.5 Instant |
|---|---|---|
| SWE-bench Verified | 79.6% | - |
| Terminal-Bench 2.0 | 59.1% | ✓82.7 |
| OSWorld-Verified | 72.5% | - |
| GPQA | 79.7% | - |
| AIME 2025 | - | 81.2 |
| FrontierMath Tier 1–3 | - | 51.7 |
Scores sourced from official provider release posts and independent benchmark aggregators.
Which should you choose?
Choose Claude Sonnet 4.6 if...
- →You have an existing integration pinned to Sonnet 4.6 and want stability
- →You need a proven mid-tier model with 1M context at $3/$15
- →You want predictable behavior without the new-tokenizer/thinking changes in Sonnet 5
- →You are cost-sensitive and don't need Sonnet 5's incremental gains
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