Grok 4.5 vs o3-mini

Grok 4.5 and o3-mini come from different labs, which means different tokenizers, different API shapes, and a second vendor relationship. The same English text does not produce the same token count on both, so a price-per-million comparison understates the difference — measure your own prompts on each before treating the headline rates as the full story.

Grok 4.5 and o3-mini are 18 months apart, which is more than one generation in this market. Benchmark comparisons across that gap flatter the older model: it was measured against the evaluations that existed at the time. Treat o3-mini's scores as a floor for what it does well and be sceptical of a close-looking result.

Grok 4.5 carries the larger context window at 500K tokens versus 200K for o3-mini. The gap is real but not decisive — it matters if your prompts routinely run long, and is irrelevant if they sit where most production prompts sit, well under 100K. Bear in mind that filling a large window is also what makes a request expensive.

Throughput is close enough to ignore — 89/100 versus 78/100. Neither model will feel noticeably quicker in an interactive product, so latency is not a reason to choose between them.

One practical asymmetry: o3-mini offers a batch API at 50% off standard rates, and Grok 4.5 does not. For anything that does not need an answer immediately — nightly enrichment, backfills, evaluation runs — that discount can be worth more than the difference in list price, and it is easy to overlook when comparing headline rates.