Model Comparison

Gemini 1.5 Flash vs Gemini 2.5 Flash

Gemini 2.5 Flash shows notably better performance in the majority of benchmarks. Gemini 1.5 Flash is 3.2x cheaper per token.

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Performance Benchmarks

Comparative analysis across standard metrics

4 benchmarks

Gemini 1.5 Flash outperforms in 1 benchmarks (MRCR), while Gemini 2.5 Flash is better at 3 benchmarks (GPQA, MMMU, Vibe-Eval).

Gemini 2.5 Flash shows notably better performance in the majority of benchmarks.

Thu Apr 30 2026 • llm-stats.com

Arena Performance

Human preference votes

Pricing Analysis

Price comparison per million tokens

Gemini 1.5 Flash costs less

For input processing, Gemini 1.5 Flash ($0.15/1M tokens) is 2.0x cheaper than Gemini 2.5 Flash ($0.30/1M tokens).

For output processing, Gemini 1.5 Flash ($0.60/1M tokens) is 4.2x cheaper than Gemini 2.5 Flash ($2.50/1M tokens).

In conclusion, Gemini 2.5 Flash is more expensive than Gemini 1.5 Flash.*

* Using a 3:1 ratio of input to output tokens

Lowest available price from all providers
Thu Apr 30 2026 • llm-stats.com
Google
Gemini 1.5 Flash
Input tokens$0.15
Output tokens$0.60
Best providerGoogle
Google
Gemini 2.5 Flash
Input tokens$0.30
Output tokens$2.50
Best providerGoogle
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Context Window

Maximum input and output token capacity

Both models have the same input context window of 1,048,576 tokens. Gemini 2.5 Flash can generate longer responses up to 65,536 tokens, while Gemini 1.5 Flash is limited to 8,192 tokens.

Google
Gemini 1.5 Flash
Input1,048,576 tokens
Output8,192 tokens
Google
Gemini 2.5 Flash
Input1,048,576 tokens
Output65,536 tokens
Thu Apr 30 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

Both Gemini 1.5 Flash and Gemini 2.5 Flash support multimodal inputs.

They are both capable of processing various types of data, offering versatility in application.

Gemini 1.5 Flash

Text
Images
Audio
Video

Gemini 2.5 Flash

Text
Images
Audio
Video

License

Usage and distribution terms

Both models are licensed under proprietary licenses.

Both models have usage restrictions defined by their respective organizations.

Gemini 1.5 Flash

Proprietary

Closed source

Gemini 2.5 Flash

Proprietary

Closed source

Release Timeline

When each model was launched

Gemini 1.5 Flash was released on 2024-05-01, while Gemini 2.5 Flash was released on 2025-05-20.

Gemini 2.5 Flash is 13 months newer than Gemini 1.5 Flash.

Gemini 1.5 Flash

May 1, 2024

2.0 years ago

Gemini 2.5 Flash

May 20, 2025

11 months ago

1.1yr newer

Knowledge Cutoff

When training data ends

Gemini 1.5 Flash has a knowledge cutoff of 2023-11-01, while Gemini 2.5 Flash has a cutoff of 2025-01-31.

Gemini 2.5 Flash has more recent training data (up to 2025-01-31), making it potentially better informed about events through that date compared to Gemini 1.5 Flash (2023-11-01).

Gemini 1.5 Flash

Nov 2023

Gemini 2.5 Flash

Jan 2025

1.2 yr newer

Provider Availability

Gemini 1.5 Flash is available from Google. Gemini 2.5 Flash is available from Google.

Gemini 1.5 Flash

google logo
Google
Input Price:Input: $0.15/1MOutput Price:Output: $0.60/1M

Gemini 2.5 Flash

google logo
Google
Input Price:Input: $0.30/1MOutput Price:Output: $2.50/1M
* Prices shown are per million tokens

Outputs Comparison

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Key Takeaways

Google
Less expensive input tokens
Less expensive output tokens
Higher MRCR score (71.9% vs 32.0%)
Google
Higher GPQA score (82.8% vs 51.0%)
Higher MMMU score (79.7% vs 62.3%)
Higher Vibe-Eval score (65.4% vs 48.9%)
GoogleGemini 1.5 Flash
GoogleGemini 2.5 Flash
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Detailed Comparison

AI Model Comparison Table
Feature
Google
Gemini 1.5 Flash
Google
Gemini 2.5 Flash

FAQ

Common questions about Gemini 1.5 Flash vs Gemini 2.5 Flash

Gemini 2.5 Flash shows notably better performance in the majority of benchmarks. Gemini 1.5 Flash is made by Google and Gemini 2.5 Flash is made by Google. The best choice depends on your use case — compare their benchmark scores, pricing, and capabilities above.
Gemini 1.5 Flash scores XSTest: 97.0%, HellaSwag: 86.5%, GSM8k: 86.2%, BIG-Bench Hard: 85.5%, MGSM: 82.6%. Gemini 2.5 Flash scores Global-MMLU-Lite: 88.4%, AIME 2024: 88.0%, FACTS Grounding: 85.3%, GPQA: 82.8%, MMMU: 79.7%.
Gemini 1.5 Flash is 2.0x cheaper for input tokens. Gemini 1.5 Flash costs $0.15/M input and $0.60/M output via google. Gemini 2.5 Flash costs $0.30/M input and $2.50/M output via google.
Gemini 1.5 Flash supports 1.0M tokens and Gemini 2.5 Flash supports 1.0M tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.
Key differences include input pricing ($0.15 vs $0.30/M). See the full comparison above for benchmark-by-benchmark results.