GPT-5 nano vs Claude Fable 5.1: cost

For a typical support chatbot, GPT-5 nano is about 134.0× cheaper than Claude Fable 5.1 ($28.14 vs $3,770 per month). Price is only one factor: test both on your own prompts before switching.

GPT-5 nano vs Claude Fable 5.1: prices and limits
GPT-5 nanoClaude Fable 5.1
Input /1M$0.05$10.00
Output /1M$0.40$50.00
Cached input /1M$0.005$0.25
Batch input /1M$0.025$5.00
Batch output /1M$0.20$25.00
Context window400,0001,000,000
Max input272,0001,000,000
Max output128,000128,000

Monthly cost by workload

Estimated monthly cost by workload (USD)
Scenario (per month)GPT-5 nanoClaude Fable 5.1
Customer support chatbot
5,000 req/day · 1,200 in · 400 out · cache 60%
$28.14$3,770
RAG over documents
2,000 req/day · 8,000 in · 600 out · cache 30%
$31.92$5,256
Coding agent
1,500 req/day · 25,000 in · 2,000 out · cache 80%
$51.75$7,256
Deep reasoning
800 req/day · 3,000 in · 6,000 out · cache 20%
$60.55$7,780
Batch processing
50,000 req/day · 1,500 in · 150 out · batch
$101$16,875