Simulating realistic AI coding assistant parameters (12,000 in / 2,000 out with 60% cache reuse). Claude Sonnet 5 delivers a 18% cost reduction over GPT-5.3 Codex.
| Traffic Volume Tier | GPT-5.3 Codex Monthly | Claude Sonnet 5 Monthly | Monthly Savings by picking Claude Sonnet 5 |
|---|---|---|---|
| 1,000 reqs/mo (Dev/Testing) | $37.66 | $31.04 | Save $6.62 / mo |
| 10,000 reqs/mo (Small App) | $376.60 | $310.40 | Save $66.20 / mo |
| 100,000 reqs/mo (Growth Production) | $3,766.00 | $3,104.00 | Save $662.00 / mo |
| 1,000,000 reqs/mo (Scale SaaS) | $37,660.00 | $31,040.00 | Save $6,620.00 / mo |
Claude Sonnet 5 is 18% cheaper for AI coding assistant workloads. At standard AI coding assistant parameter ratios (12,000 input tokens, 2,000 output tokens, 60% cache hit), Claude Sonnet 5 costs $0.031 per request compared to $0.0377 on GPT-5.3 Codex.
GPT-5.3 Codex offers a context window of 256,000 tokens (max output: 64,000), while Claude Sonnet 5 offers 1,000,000 tokens (max output: 128,000).
At 100,000 requests per month, using Claude Sonnet 5 saves $662.00 every month (or $7,944.00 annually) compared to GPT-5.3 Codex.
Output is the expensive side — prefer models with cheap output for autocomplete-style calls. Cache repository context between keystrokes; diffs change far less than the full file. Measure acceptance rate: paying for output users delete is pure waste.