Head-to-head showdown: GPT-5.3 Codex ($1.75 in / $14.00 out per 1M) vs Claude Fable 5 ($10.00 in / $50.00 out per 1M). GPT-5.3 Codex is 3.8× cheaper across standard token mixes, with 256K vs 1M context windows.
gpt-5.3-codex · openai
claude-fable-5 · anthropic
Benchmark
| Workload Scenario | GPT-5.3 Codex | Claude Fable 5 | Price Delta |
|---|---|---|---|
| 1M input tokens (raw text) | $1.75 | $10.00 | −$8.25 |
| 1M output tokens (generation) | $14.00 | $50.00 | −$36.00 |
| 1M tokens · 70% input / 30% output mix | $5.425 | $22.00 | −$16.575 |
| Standard chat turn (4K in / 800 out, 50% cached) | $0.0151 | $0.062 | −$0.047 |
| Monthly scale (10K requests / day) | $4,515.00 | $18,600.00 | −$14,085.00 |
Negative difference = GPT-5.3 Codex is cheaper. Positive = Claude Fable 5 is cheaper.
Scaling Curve
Total cost of a token volume at 70/30 input/output split (uncached). Log-log scale.
Verdict
GPT-5.3 Codex is cheaper on both input and output rates, so it costs less at every input/output mix. Price alone still isn't the whole decision: capability, latency and context limits (GPT-5.3 Codex: 256K, Claude Fable 5: 1M) may justify the premium for your task.
FAQ
On input, GPT-5.3 Codex is cheaper ($1.75/M vs $10.00/M). On output, GPT-5.3 Codex is cheaper ($14.00/M vs $50.00/M). The same model is cheaper on both sides, so it wins at every mix.
A chat-style request (4,000 input + 800 output tokens, 50% cached) costs $0.0151 on GPT-5.3 Codex and $0.062 on Claude Fable 5 — GPT-5.3 Codex is 4.1× cheaper for that workload.
GPT-5.3 Codex supports 256,000 tokens (64K max output); Claude Fable 5 supports 1,000,000 (128K max output). Claude Fable 5 fits 3.9× more context, which matters for long documents and agents.