Side-by-side benchmark comparison across knowledge, coding, math, and reasoning.
Claude Haiku 4.5 is clearly ahead on the aggregate, 64 to 31. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.
Claude Haiku 4.5 is also the more expensive model on tokens at $0.80 input / $4.00 output per 1M tokens, versus $0.05 input / $0.40 output per 1M tokens for GPT-5 nano. That is roughly 10.0x on output cost alone. GPT-5 nano is the reasoning model in the pair, while Claude Haiku 4.5 is not. That usually helps on harder chain-of-thought-heavy tests, but it can also mean more latency and more token spend in real use. GPT-5 nano gives you the larger context window at 400K, compared with 200K for Claude Haiku 4.5.
Pick Claude Haiku 4.5 if you want the stronger benchmark profile. GPT-5 nano only becomes the better choice if mathematics is the priority or you want the cheaper token bill.
Claude Haiku 4.5
57.8
GPT-5 nano
71.2
Claude Haiku 4.5
68.8
GPT-5 nano
85.2
Claude Haiku 4.5 is ahead overall, 64 to 31. The biggest single separator in this matchup is AIME 2025, where the scores are 69 and 85.2.
GPT-5 nano has the edge for knowledge tasks in this comparison, averaging 71.2 versus 57.8. Inside this category, GPQA is the benchmark that creates the most daylight between them.
GPT-5 nano has the edge for math in this comparison, averaging 85.2 versus 68.8. Inside this category, AIME 2025 is the benchmark that creates the most daylight between them.
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