Claude Sonnet 5.5 vs GPT-5.3 Codex Spark
Price and specs side by side · USD per 1M tokens · verified 2026-10-11
// side by side
| metric | Claude Sonnet 5.5 | GPT-5.3 Codex Spark |
|---|
| input / 1M | $2.00 | $1.75 |
| output / 1M | $10.00 | $14.00 |
| blended (3:1) | $4.00 | $4.8125 |
| cache read / 1M | $0.10 | $0.175 |
| context | 1M | 128K |
| max output | 128K | 32K |
| input types | text · image · pdf | text · image · pdf |
| reasoning | yes | yes |
| tool calling | yes | yes |
| structured output | yes | yes |
| open weights | no | no |
| released | 2026-09-28 | 2026-02-05 |
| knowledge cutoff | 2026-06 | 2025-08-31 |
| lab | Anthropic | OpenAI |
// monthly cost scenarios
| workload | tokens in / out | Claude Sonnet 5.5 | GPT-5.3 Codex Spark |
|---|
| Chatbot | 10M / 2M | $40.00 | $45.50 |
| RAG app | 50M / 5M | $150 | $158 |
| Coding agent | 20M / 10M | $140 | $175 |
// verdict
- Claude Sonnet 5.5 is 16.9% cheaper than GPT-5.3 Codex Spark on a blended 3:1 input/output basis.
- Claude Sonnet 5.5 has the larger context window (1M vs 128K tokens).