Gemini 2.5 Flash vs o3
Google vs OpenAI · Prices checked 12 August 2026
On blended cost Gemini 2.5 Flash undercuts o3 by about 66.7×: $0.285 per million tokens versus $19.00. A single 100K-input, 10K-output job costs $0.021 on Gemini 2.5 Flash against $1.40 on o3.
Of the 6 shared benchmarks, o3 takes 6. The widest gap is on LMArena Elo, where o3 leads by 55 points. On context, Gemini 2.5 Flash is the larger at 1,000,000 tokens versus 200,000.
Pricing and capacity
| Metric | Gemini 2.5 Flash | o3 | Difference |
|---|---|---|---|
| Input / 1M tokens | $0.150 | $10.00 | 66.7× |
| Output / 1M tokens | $0.600 | $40.00 | 66.7× |
| Blended · 70/30calculated | $0.285 | $19.00 | 66.7× |
| Blended · 50/50calculated | $0.375 | $25.00 | 66.7× |
| Blended · 80/20calculated | $0.240 | $16.00 | 66.7× |
| Blended · 20/80calculated | $0.510 | $34.00 | 66.7× |
| Job cost · 100K + 10Kcalculated | $0.021 | $1.40 | 66.7× |
| Job cost · 1M + 100Kcalculated | $0.210 | $14.00 | 66.7× |
| Context window | 1,000,000 | 200,000 | 5.0× |
Input and output rates are as published by each provider. Blended and job-cost rows are calculated comparison metrics, not published prices — how they are derived.
Benchmarks
| Benchmark | Gemini 2.5 Flash | o3 | Leader |
|---|---|---|---|
| MMLU | 84% | 90% | o3 |
| GPQA Diamond | 70% | 88% | o3 |
| MATH | 87% | 96% | o3 |
| HumanEval | 87% | 95% | o3 |
| SWE-bench Verified | 48% | 71% | o3 |
| LMArena Elo | 1325 Elo | 1380 Elo | o3 |
Only suites both models report are listed, so a missing score is never shown as a loss. Figures are provider-published or from public leaderboards and are not independently re-run.
What each model is for
Gemini 2.5 Flash
Google · Balanced
Speed-optimised Gemini for high-throughput production. Same multimodal surface as Pro at a fraction of the price.
- Fast
- 1M context
- Native multimodal
- Very cheap
Frequently asked questions
Which is cheaper, Gemini 2.5 Flash or o3?
On blended cost Gemini 2.5 Flash undercuts o3 by about 66.7×: $0.285 per million tokens versus $19.00. A single 100K-input, 10K-output job costs $0.021 on Gemini 2.5 Flash against $1.40 on o3. Blended cost weights input at 70% and output at 30%; price your own token split for an exact answer, since the cheaper model on a blended basis is not always cheaper for your workload.
Which performs better, Gemini 2.5 Flash or o3?
Of the 6 shared benchmarks, o3 takes 6. The widest gap is on LMArena Elo, where o3 leads by 55 points. These are the figures each provider or public leaderboard publishes, not results we re-run, and a benchmark average can hide the specific behaviour your workload depends on.
Which has the larger context window, Gemini 2.5 Flash or o3?
On context, Gemini 2.5 Flash is the larger at 1,000,000 tokens versus 200,000. The context window caps everything in a single request: prompt, retrieved documents, conversation history and the model’s own output all share it.
Can I compare Gemini 2.5 Flash and o3 on my own numbers?
Yes. Open both in the side-by-side comparison tool to see every field at once, or use the token calculator to price your actual prompt and monthly request volume against each model. Both are free and need no sign-up.
Price it for your own workload
Related matchups
Terms used on this page
Prices and scores are recomputed on every deploy from the catalogue. Prices checked 12 August 2026.