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Gemini 1.5 Pro vs Gemini 3.8 Flash

Gemini 3.8 Flash leads the LLM Stats Score 51.3 to 12.2. Gemini 3.8 Flash is 2.9x cheaper per token.

Google · Google · Updated for 2026

Which is better?

Gemini 3.8 Flash leads the overall LLM Stats Score 51.3 to 12.2, ranking #14 overall.

On price, Gemini 3.8 Flash is roughly 2.9x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.

Gemini 1.5 Pro also accepts a larger context window (2,097,152 input tokens), making it the stronger choice for long documents and large codebases.

Based on current LLM Stats indexes, shared benchmarks, pricing, and model metadata for 2026.

Choose Gemini 1.5 Pro

  • you process long inputs — it offers a 2,097,152 token context window

Choose Gemini 3.8 Flash

  • overall performance matters — it scores 51.3 and ranks #14 on LLM Stats
  • your work emphasizes reasoning and coding — it leads those capability indexes
  • cost matters — it's about 2.9x cheaper per token
  • you want the most recent training data — it shipped Sep 2026

At a glance

The differences that matter most.

Gemini 1.5 Pro
Google
Gemini 3.8 Flash
Google
Core performance indexes
LLM Stats Score
12.2
#243
51.3
#14
Reasoning
12.0
#236
47.2
#23
Coding
4.4
#200
39.9
#12
Cost, coverage & limits
Benchmark wins
—
—
Input price
$2.50 / M
$0.75 / M
Output price
$10.00 / M
$3.75 / M
Context window
2,097,152
1,048,576

Capability indexes

Additional strengths measured across groups of related public benchmarks

2 shared
Index
Gemini 1.5 Pro
Gemini 3.8 Flash
Vision
9.7#123
34.0#12
Multimodal
13.8#95
35.0#11
Conservative TrueSkill rating · higher is betterHow scores work

Individual benchmarks

23 reported for Gemini 1.5 Pro · 13 for Gemini 3.8 Flash

No common benchmarks found

Gemini 1.5 Pro and Gemini 3.8 Flashdon't have any common benchmark datasets to compare. They may have been evaluated on different testing suites.

Human preference

Blind head-to-head votes and playground preference scores

Pricing Analysis

Price comparison per million tokens

Gemini 3.8 Flash costs less

For input processing, Gemini 1.5 Pro ($2.50/1M tokens) is 3.3x more expensive than Gemini 3.8 Flash ($0.75/1M tokens).

For output processing, Gemini 1.5 Pro ($10.00/1M tokens) is 2.7x more expensive than Gemini 3.8 Flash ($3.75/1M tokens).

In conclusion, Gemini 1.5 Pro is more expensive than Gemini 3.8 Flash.*

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

Lowest available price from all providers
Thu Sep 03 2026 • llm-stats.com
Google
Gemini 1.5 Pro
Input tokens$2.50
Output tokens$10.00
Best providerGoogle
Google
Gemini 3.8 Flash
Input tokens$0.75
Output tokens$3.75
Best providerGoogle
Notice missing or incorrect data?Start an Issue→

Context Window

Maximum input and output token capacity

Gemini 1.5 Pro accepts 2,097,152 input tokens compared to Gemini 3.8 Flash's 1,048,576 tokens. Gemini 3.8 Flash can generate longer responses up to 65,536 tokens, while Gemini 1.5 Pro is limited to 8,192 tokens.

Google
Gemini 1.5 Pro
Input2,097,152 tokens
Output8,192 tokens
Google
Gemini 3.8 Flash
Input1,048,576 tokens
Output65,536 tokens
Thu Sep 03 2026 • llm-stats.com

Input capabilities

Documented input modalities across available providers

Both Gemini 1.5 Pro and Gemini 3.8 Flash support multimodal inputs.

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

Gemini 1.5 Pro

Text
Images
Audio
Video

Gemini 3.8 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 Pro

Proprietary

Closed source

Gemini 3.8 Flash

Proprietary

Closed source

Release Timeline

When each model was launched

Gemini 1.5 Pro was released on 2024-05-01, while Gemini 3.8 Flash was released on 2026-09-02.

Gemini 3.8 Flash is 28 months newer than Gemini 1.5 Pro.

Gemini 1.5 Pro

May 1, 2024

2.3 years ago

Gemini 3.8 Flash

Sep 2, 2026

0 days ago

2.3yr newer

Knowledge Cutoff

When training data ends

Gemini 1.5 Pro has a knowledge cutoff of 2023-11-01, while Gemini 3.8 Flash has a cutoff of 2026-03-31.

Gemini 3.8 Flash has more recent training data (up to 2026-03-31), making it potentially better informed about events through that date compared to Gemini 1.5 Pro (2023-11-01).

Gemini 1.5 Pro

Nov 2023

Gemini 3.8 Flash

Mar 2026

2.3 yr newer

Provider Availability

Gemini 1.5 Pro is available from Google. Gemini 3.8 Flash is available from Google.

Gemini 1.5 Pro

google logo
Google
Input Price:Input: $2.50/1MOutput Price:Output: $10.00/1M

Gemini 3.8 Flash

google logo
Google
Input Price:Input: $0.75/1MOutput Price:Output: $3.75/1M
* Prices shown are per million tokens

Outputs Comparison

Notice missing or incorrect data?Start an Issue discussion→

Judge for yourself.

Run your own prompts against Gemini 1.5 Pro and Gemini 3.8 Flash side-by-side, then vote on the output you prefer.

Gemini 1.5 Pro
✓ Preferred
Gemini 3.8 Flash
Open in Playground

FAQ

Common questions about Gemini 1.5 Pro vs Gemini 3.8 Flash.

Which is better, Gemini 1.5 Pro or Gemini 3.8 Flash?

Gemini 3.8 Flash leads the LLM Stats Score 51.3 to 12.2. Gemini 1.5 Pro is made by Google and Gemini 3.8 Flash is made by Google. The best choice depends on your use case — compare their capability indexes, individual benchmarks, pricing, and limits above.

How does Gemini 1.5 Pro compare to Gemini 3.8 Flash in benchmarks?

Gemini 1.5 Pro scores XSTest: 98.8%, FLEURS: 93.3%, HellaSwag: 93.3%, GSM8k: 90.8%, BIG-Bench Hard: 89.2%. Gemini 3.8 Flash scores Terminal-Bench 2.1: 89.4%, LVBench: 87.1%, CharXiv-R: 86.2%, LABBench2: 86.2%, DeepSWE 1.1: 73.7%.

Is Gemini 1.5 Pro cheaper than Gemini 3.8 Flash?

Gemini 3.8 Flash is 3.3x cheaper for input tokens. Gemini 1.5 Pro costs $2.50/M input and $10.00/M output via google. Gemini 3.8 Flash costs $0.75/M input and $3.75/M output via google.

What are the context window sizes for Gemini 1.5 Pro and Gemini 3.8 Flash?

Gemini 1.5 Pro supports 2.1M tokens and Gemini 3.8 Flash supports 1.0M tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.

What are the main differences between Gemini 1.5 Pro and Gemini 3.8 Flash?

Key differences include LLM Stats Score (12.2 vs 51.3), context window (2.1M vs 1.0M), input pricing ($2.50 vs $0.75/M). See the full comparison above for benchmark-by-benchmark results.

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