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AI Choice Engine

Model comparison

Gemini 2.5 Pro vs Gemini 3.1 Flash-Lite

Two Google tiers compared on the figures that decide which one a workload actually needs.

Catalog record checked September 26, 2026Individual provider fields may changeEvidence confidence: Medium — see receipts below

Google

Gemini 2.5 Pro

Balanced

vs

Google

Gemini 3.1 Flash-Lite

Budget

AI model capability comparison
SpecificationGemini 2.5 ProGemini 3.1 Flash-Lite
ProviderGoogleGoogle
TierBalancedBudget
Context window1.05M1.05M
Max output66K66K
Input / 1M tokens$1.25Winner: $0.25
Output / 1M tokens$10Winner: $1.50
WeightsClosedClosed
ParametersNot disclosedUnverifiedNot disclosedUnverified
Reasoning levelslow, medium, highNot verifiedUnverified
Modalitiestext, image, video, audio, pdftext, image, video, audio, pdf
API model idgemini-2.5-progemini-3.1-flash-lite
ReleasedJune 17, 2025May 7, 2026
Artificial Analysis Intelligence Index (2026-09-26)Winner: 16.115.6

Prices are USD per million tokens at standard rates, excluding batch and caching discounts. Bold indicates the better figure where one is objectively better. Values we could not confirm from the provider are shown as “Not verified” rather than estimated.

Benchmark receipts

Where each score comes from, and how far it can be compared across models.

  • 2026-09-26
    Artificial Analysis

    Composite index blending reasoning, knowledge, and coding evals into one 0–100 score.

    Comparable with caveatOnly same-version scores are comparable. v4.3.2 was rebaselined (the top score fell from 66 on v4.1.1 to ~58), so v4.1.1 figures must not be compared with v4.3.2 figures — check measuredAt.

Pricing tiers

Gemini 2.5 Pro: $1.25/$10 per MTok (≤200K); $2.50/$15 (>200K). Legacy but still widely listed.

Gemini 3.1 Flash-Lite: $0.25 input (text, image, video; $0.50 audio) / $1.50 output per MTok; cached input $0.025. GA 2026-05-07 after a 2026-03-03 preview; shutdown no earlier than 2027-05-07.

BalancedRecord checked September 26, 2026

Gemini 2.5 Pro

Gemini 2.5 Pro is Google's previous-generation Pro with a 1.05M-token context and strong multimodal support.

Best for

  • Long documents
  • Multimodal input
  • Google Workspace integration

Watch out

Since 2026-09-18 Google limits Gemini API access to existing 2.5 users (new projects are pointed to 3.8 Flash or 3.5 Flash-Lite); the Gemini API deprecations page shows no shutdown date — check Vertex AI's lifecycle page separately.

BudgetRecord checked September 26, 2026

Gemini 3.1 Flash-Lite

Gemini 3.1 Flash-Lite is Google's cheapest current Gemini API model for high-volume, latency-sensitive pipelines.

Best for

  • High-volume extraction
  • Classification
  • Cheap multimodal input

Watch out

Google recommends 3.5 Flash-Lite for new work, and 3.1 Flash-Lite's earliest shutdown date is 2027-05-07; well behind Flash models on reasoning.

When the cheaper one wins

Gemini 3.1 Flash-Lite is cheaper on output at $1.50 per million tokens against $10 for Gemini 2.5 Pro — about 6.7×. Use the cheaper tier for classification, extraction, summarisation, and any task where the expensive model’s extra score does not change the accepted output. The expensive one only pays if your hardest task actually fails on the cheap tier. These are standard-tier API rates, excluding batch and cache discounts.

Run the model picker

Evidence confidence: Medium

How strong and complete the evidence behind this comparison is — not a prediction of which model is better.

  • Pricing verified on both sides — Input and output rates are verified for both models.
  • 3/5 core specs verified on both sides — Not published for at least one side: parameter count, reasoning levels.
  • 1 shared named benchmark (scores match) — Measured on: Artificial Analysis Intelligence Index — scores are equivalent, so the benchmark does not separate the pair.
  • Verified within the last 90 days — Newest catalog check was 2 days ago.
  • Both models carry source citations — Each side has at least two catalog sources on record.

Source receipts

Each catalog figure was checked against the provider or an independent second source on the date shown.

Related comparisons

Diving deeper on one model? Gemini 2.5 Pro · Gemini 3.1 Flash-Lite

Common questions

Gemini 2.5 Pro vs Gemini 3.1 Flash-Lite

Answered from the verified figures on this page rather than general guidance.

Is Gemini 2.5 Pro or Gemini 3.1 Flash-Lite cheaper for input?
Gemini 3.1 Flash-Lite is cheaper at $0.25 per million input tokens, against $1.25 for Gemini 2.5 Pro — roughly 5.0× the price. Output tokens usually dominate a real bill, so weigh the output rate more heavily than the input rate. These are base rates; Gemini 2.5 Pro has tiered pricing: $1.25/$10 per MTok (≤200K); $2.50/$15 (>200K). Legacy but still widely listed. Gemini 3.1 Flash-Lite has tiered pricing: $0.25 input (text, image, video; $0.50 audio) / $1.50 output per MTok; cached input $0.025. GA 2026-05-07 after a 2026-03-03 preview; shutdown no earlier than 2027-05-07.
Is Gemini 2.5 Pro or Gemini 3.1 Flash-Lite cheaper for output?
Gemini 3.1 Flash-Lite is cheaper at $1.50 per million output tokens, against $10 for Gemini 2.5 Pro — roughly 6.7× the price. Output tokens usually dominate a real bill, so weigh the output rate more heavily than the input rate. These are base rates; Gemini 2.5 Pro has tiered pricing: $1.25/$10 per MTok (≤200K); $2.50/$15 (>200K). Legacy but still widely listed. Gemini 3.1 Flash-Lite has tiered pricing: $0.25 input (text, image, video; $0.50 audio) / $1.50 output per MTok; cached input $0.025. GA 2026-05-07 after a 2026-03-03 preview; shutdown no earlier than 2027-05-07.
Which has the larger context window, Gemini 2.5 Pro or Gemini 3.1 Flash-Lite?
Both accept about 1.05M tokens of context, so document length will not decide between them.
Should I use Gemini 2.5 Pro or Gemini 3.1 Flash-Lite?
Gemini 2.5 Pro is the balanced tier and Gemini 3.1 Flash-Lite the budget tier. The useful question is whether your hardest task actually fails on the cheaper one — most production volume such as classification, extraction and summarisation does not.

Next step

Choosing between them

The verified figures that separate this pair, computed from the catalog rather than restated boilerplate.

  • Input price: Gemini 3.1 Flash-Lite costs $0.25 per 1M tokens versus $1.25 for Gemini 2.5 Pro — a 5x difference at the headline tier.
  • Measured capability: Gemini 2.5 Pro leads Artificial Analysis Intelligence Index 16.1 to 15.6 (measured 2026-09-26).
  • Positioning: Gemini 2.5 Pro sits in the balanced tier, Gemini 3.1 Flash-Lite in the budget tier — most production volume (classification, extraction, summarisation) does not need the pricier tier.
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