GPT-5 vs Gemini 2.5 Flash
OpenAI vs Google · Prices checked 12 August 2026
Gemini 2.5 Flash is the cheaper of the two by a wide margin: $0.285 per million tokens blended against $3.88, roughly 13.6× less. A single 100K-input, 10K-output job costs $0.021 on Gemini 2.5 Flash against $0.225 on GPT-5.
GPT-5 leads on 6 of the 6 benchmarks both models report. The widest gap is on LMArena Elo, where GPT-5 leads by 74 points. Gemini 2.5 Flash takes a 1,000,000-token context window against 400,000, giving 2.5× more room for long documents or whole-codebase work.
Pricing and capacity
| Metric | GPT-5 | Gemini 2.5 Flash | Difference |
|---|---|---|---|
| Input / 1M tokens | $1.25 | $0.150 | 8.3× |
| Output / 1M tokens | $10.00 | $0.600 | 16.7× |
| Blended · 70/30calculated | $3.88 | $0.285 | 13.6× |
| Blended · 50/50calculated | $5.63 | $0.375 | 15.0× |
| Blended · 80/20calculated | $3.00 | $0.240 | 12.5× |
| Blended · 20/80calculated | $8.25 | $0.510 | 16.2× |
| Job cost · 100K + 10Kcalculated | $0.225 | $0.021 | 10.7× |
| Job cost · 1M + 100Kcalculated | $2.25 | $0.210 | 10.7× |
| Context window | 400,000 | 1,000,000 | 2.5× |
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 | GPT-5 | Gemini 2.5 Flash | Leader |
|---|---|---|---|
| MMLU | 91% | 84% | GPT-5 |
| GPQA Diamond | 84% | 70% | GPT-5 |
| MATH | 95% | 87% | GPT-5 |
| HumanEval | 96% | 87% | GPT-5 |
| SWE-bench Verified | 75% | 48% | GPT-5 |
| LMArena Elo | 1399 Elo | 1325 Elo | GPT-5 |
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
GPT-5
OpenAI · Frontier
OpenAI's 2025 flagship, unified reasoning + multimodal model with a 400K context. Replaces the GPT-4 line as the default ChatGPT and API model.
- Unified reasoning + chat
- 400K context
- Native vision
- Strong tool use
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, GPT-5 or Gemini 2.5 Flash?
Gemini 2.5 Flash is the cheaper of the two by a wide margin: $0.285 per million tokens blended against $3.88, roughly 13.6× less. A single 100K-input, 10K-output job costs $0.021 on Gemini 2.5 Flash against $0.225 on GPT-5. 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, GPT-5 or Gemini 2.5 Flash?
GPT-5 leads on 6 of the 6 benchmarks both models report. The widest gap is on LMArena Elo, where GPT-5 leads by 74 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, GPT-5 or Gemini 2.5 Flash?
Gemini 2.5 Flash takes a 1,000,000-token context window against 400,000, giving 2.5× more room for long documents or whole-codebase work. 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 GPT-5 and Gemini 2.5 Flash 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.