Gemini 2.5 Flash vs o3
A complete head-to-head: pricing, context window, benchmarks, modality coverage, and openness, with a programmatic verdict synthesized from the underlying data.
Updated
Gemini 2.5 Flash specs · o3 specs- PriceGemini 2.5 Flash
Gemini 2.5 Flash is roughly 26.7× cheaper on output tokens ($0.30 vs $8.00 per 1M).
- Context windowGemini 2.5 Flash
Gemini 2.5 Flash accepts 1.0M tokens vs 200K, 5.2× the room for long documents and codebases.
- BenchmarksTie
No directly comparable public benchmarks are available for both models, check the spec sheets for individual scores.
- ModalitiesGemini 2.5 Flash
Gemini 2.5 Flash supports 3 modalities (text, vision, audio) vs 2 for o3.
- OpennessTie
Both are closed-weight, API-only.
On balance Gemini 2.5 Flash edges ahead, winning 3 of 5 categories against o3's 0. Gemini 2.5 Flash is roughly 26.7× cheaper on output tokens ($0.30 vs $8.00 per 1M). Gemini 2.5 Flash accepts 1.0M tokens vs 200K, 5.2× the room for long documents and codebases.
No directly comparable public benchmarks are available for both models, check the spec sheets for individual scores. They differ in modality coverage, Gemini 2.5 Flash handles text, vision, audio while o3 handles text, vision, which can be the deciding factor before you even look at benchmarks. Both are closed-weight, API-only.
Both shipped within roughly a month of each other in 2025, so they share the same generation of training data and tooling. Gemini 2.5 Flash is usually picked for rag and long context workloads, while o3 sees more deployments in reasoning and math. If pricing matters more than every last benchmark point, run the numbers in the calculator below before committing.
Side-by-side specs
| Spec | Gemini 2.5 Flash | o3 |
|---|---|---|
| Provider | OpenAI | |
| Released | Apr 2025 | Apr 2025 |
| Modalities | text, vision, audio | text, vision |
| Context window | 1.0M tokens | 200K tokens |
| Max output | , | , |
| Input · 1M | $0.075 / 1M tokens | $2.00 / 1M tokens |
| Output · 1M | $0.30 / 1M tokens | $8.00 / 1M tokens |
| Knowledge cutoff | 2025-01 | 2024-06 |
| Open weights | No | No |
| API available | Yes | Yes |
Pricing at scale
What you'd actually pay at typical workloads. Numbers come from each model's published per-million-token rates.
- Light usage, 100k in / 50k out per day$0.675 vs $18.00
- Heavy usage, 1M in / 500k out per day$6.75 vs $180
- RAG workload, 5M in / 200k out per day$13.05 vs $348
Light usage, 100k in / 50k out per day: $0.675 vs $18.00 per month, model A comes out ahead. Heavy usage, 1M in / 500k out per day: $6.75 vs $180 per month, model A comes out ahead. RAG workload, 5M in / 200k out per day: $13.05 vs $348 per month, model A comes out ahead.
Estimated spend for the listed models at your usage. Numbers are derived from each model's published per-million-token rates.
- Gemini 2.5 Flash$0.022
- o3$0.600
Benchmarks compared
Only sourced numbers. Where a benchmark is missing for one model we show the available value rather than fabricating the other.
- HumanEval,95.0
- GPQA,87.7
Gemini 2.5 Flash fits when…
- Cheap and fast
- Long context
- Solid vision
- Cost-sensitive workloads, 26.7× cheaper than o3 on output tokens.
- Long-context tasks, handles 1.0M tokens vs 200K for o3.
o3 fits when…
- Industry-leading reasoning depth at launch
- Strong on math, science, and abstract puzzles
- Tool-use during reasoning loops
Consider Gemini 3 Pro
Google's late-2025 flagship, set new benchmarks on long-context, vision, and reasoning at competitive pricing.
Frequently asked
Is Gemini 2.5 Flash or o3 cheaper?
Gemini 2.5 Flash is cheaper at $0.30 / 1M tokens per million output tokens, vs $8.00 / 1M tokens for o3.Which has the larger context window?
Gemini 2.5 Flash accepts 1.0M tokens vs 200K for o3.Is Gemini 2.5 Flash or o3 better for coding?
Both Gemini 2.5 Flash and o3 are competitive on coding benchmarks. See each model's individual spec page for HumanEval and SWE-bench scores where published. For an opinionated pick, consult our Best LLM for Coding ranking.Are either of these models open source?
Neither model ships open weights, both are accessible only via their respective providers' APIs.When were Gemini 2.5 Flash and o3 released?
Gemini 2.5 Flash was released by Google on 2025-04-09. o3 was released by OpenAI on 2025-04-16.
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