Comparison · prices as of 2026-07-04 · re-verified 2026-08-18
Claude Haiku 4.5 vs GPT-5.1
On price alone, Claude Haiku 4.5 (Anthropic) runs about 40% cheaper than GPT-5.1 for a typical chat workload (2K input + 500 output tokens, 1,000 requests/day). Whether that's the right trade depends on the capability gap — the breakdown below shows where each one wins.
Price per million tokens
| Spec | Claude Haiku 4.5 | GPT-5.1 |
|---|---|---|
| Input / MTok | $1 | $1.25 |
| Output / MTok | $5 | $10 |
| Context window | 200K | 400K |
| Max output | 64K | 128K |
| Class | fast / lightweight | frontier |
Estimated monthly cost by workload
Same models, three realistic usage levels. The gap between them scales with volume, so the right pick can change as you grow.
| Workload | Claude Haiku 4.5 | GPT-5.1 | Cheaper |
|---|---|---|---|
| Light — chatbot 0.5K in / 0.2K out · 200 req/day | $9.00 | $15.75 | Claude Haiku 4.5 |
| Typical — assistant 2K in / 0.5K out · 1K req/day | $135 | $225 | Claude Haiku 4.5 |
| Heavy — RAG / agent 8K in / 2K out · 5K req/day | $2,700 | $4,500 | Claude Haiku 4.5 |
Which should you pick?
- Cheapest overall: Claude Haiku 4.5 — about 40% less per month on a typical assistant workload.
- Claude Haiku 4.5 is cheaper on both input and output, so it stays cheaper whether your workload is prompt-heavy or generation-heavy.
- Largest context window: GPT-5.1 at 400K tokens vs 200K — the one to pick if you feed in whole documents or codebases.
- Different classes: Claude Haiku 4.5 is a fast / lightweight model, GPT-5.1 is a frontier model — expect GPT-5.1 to be stronger on hard reasoning and Claude Haiku 4.5 to be faster and cheaper to run.
Frequently asked questions
Is Claude Haiku 4.5 or GPT-5.1 cheaper?
Claude Haiku 4.5 is cheaper — roughly 40% less per month on a typical assistant workload (2K input + 500 output tokens, 1,000 requests/day).
What do Claude Haiku 4.5 and GPT-5.1 cost per million tokens?
Claude Haiku 4.5 is $1 per million input tokens and $5 per million output. GPT-5.1 is $1.25 input and $10 output. Prices are first-party API list rates as of 2026-07-04.
Which has the larger context window, Claude Haiku 4.5 or GPT-5.1?
GPT-5.1 does, at 400K tokens versus 200K for Claude Haiku 4.5.
When should I choose GPT-5.1 over Claude Haiku 4.5?
Choose GPT-5.1 when you need the extra capability of its frontier class; drop to Claude Haiku 4.5 when speed and cost matter more than peak quality.
Related comparisons
Sources: Anthropic pricing · OpenAI pricing. Run your own numbers in the cost calculator.