Claude Haiku 4.5 vs OpenAI o4-mini
The cheaper model depends on how much output you generate: Claude Haiku 4.5 wins 1 of 3 workloads, OpenAI o4-mini takes the rest.
List prices checked
Specifications and rates
| Property | Claude Haiku 4.5 | OpenAI o4-mini |
|---|---|---|
| Input per 1M | $1.00 | $1.10 |
| Output per 1M | $5.00 | $4.40 |
| Cached input per 1M | $0.100 | $0.275 |
| Blended (3:1) | $2.00 | $1.93 |
| Context window | 200K | 200K |
| Max output | 64K | 100K |
| Inputs accepted | text, image | text, image |
Source: Anthropic pricing (August 2026) · OpenAI pricing (May 2026). Published list prices only — committed-use discounts, regional variation, and per-request charges are not included. Not yet independently re-checked against the vendor’s page.
Monthly cost by workload
Identical token volumes through both rate cards. Output-heavy profiles are where the ranking flips.
| Workload | Claude Haiku 4.5 | OpenAI o4-mini | Cheaper |
|---|---|---|---|
| In-app chat assistantA support or help assistant handling a few thousand conversations a month, with short prompts and short answers. | $45 | $44 | OpenAI o4-minisaves $1.00/mo (2%) |
| RAG over documentsRetrieval-augmented answering where each request stuffs several retrieved passages into the prompt, so input dominates. | $375 | $396 | Claude Haiku 4.5saves $21/mo (5%) |
| Coding agentAn agentic loop that reads files and writes patches, generating heavy output and re-sending large context on every turn. | $900 | $880 | OpenAI o4-minisaves $20/mo (2%) |
What each one is for
Claude Haiku 4.5
by Anthropic
The fast, cheap end of the Claude family, priced at a third of Sonnet while keeping the same context window. Suited to classification, extraction, and high-volume routing.
OpenAI o4-mini
by OpenAI
Cheap reasoning, strong on maths and code relative to its price. Same caveat as every reasoning model: budget for the thinking tokens, not just the visible answer.
Common questions
- Is Claude Haiku 4.5 or OpenAI o4-mini cheaper in 2026?
- It depends on the shape of the workload. Claude Haiku 4.5 is cheaper for 1 of the 3 profiles below and OpenAI o4-mini for the rest — the split follows how much output each workload generates.
- Which has the larger context window?
- Both accept 200K tokens.
- Which is cheaper for output-heavy work like agents?
- OpenAI o4-mini, at $4.40 per million output tokens against $5.00. Reasoning tokens bill as output, so for agentic loops this axis usually decides the invoice regardless of what the input rates look like.
- What is not included in these figures?
- Batch-processing discounts, fine-tuning, long-context surcharges above a provider's standard tier, and any enterprise agreement. These are published pay-as-you-go list prices, checked against each provider's own pricing page on the date shown.
- Is switching from Claude Haiku 4.5 to OpenAI o4-mini worth it?
- On price alone it is about 4% cheaper on a blended basis. Whether that survives contact with your workload depends on output quality and on retry rate — a cheaper model that needs two attempts is not cheaper. Model the specific volumes in the calculator before you migrate.