Model comparison

Gemini 3.1 Flash-Lite vs Gemini 3.1 Pro

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: High — see receipts below

Google

Gemini 3.1 Flash-Lite

Budget

Google

Gemini 3.1 Pro

Frontier

AI model capability comparison
Specification	Gemini 3.1 Flash-Lite	Gemini 3.1 Pro
Provider
Provider	Google	Google
Tier
Tier	Budget	Frontier
Context window
Context window	1.05M	1.05M
Max output
Max output	66K	66K
Input / 1M tokens
Input / 1M tokens	Winner: $0.25	$2
Output / 1M tokens
Output / 1M tokens	Winner: $1.50	$12
Weights
Weights	Closed	Closed
Parameters
Parameters	Not disclosedUnverified	Not disclosedUnverified
Reasoning levels
Reasoning levels	Not verifiedUnverified	low, medium, high
Modalities
Modalities	text, image, video, audio, pdf	text, image, video, audio, pdf
API model id
API model id	gemini-3.1-flash-lite	gemini-3.1-pro-preview
Released
Released	May 7, 2026	February 19, 2026
Artificial Analysis Intelligence Index (2026-09-26)
Artificial Analysis Intelligence Index (2026-09-26)	15.6	Winner: 29.7
SWE-bench Verified (2026-02)
SWE-bench Verified (2026-02)	Not verifiedUnverified	80.6
GPQA Diamond (2026-02)
GPQA Diamond (2026-02)	Not verifiedUnverified	94.3
Humanity's Last Exam (2026-02)
Humanity's Last Exam (2026-02)	Not verifiedUnverified	44.4
Terminal-Bench 2.1 (2026-07)
Terminal-Bench 2.1 (2026-07)	Not verifiedUnverified	73.8

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.
2026-07
Google DeepMind model evaluation report (vendor, Terminus-2; own Feb report separately reported TB 2.0 = 68.5 — versions preserved)
Agentic terminal work: multi-step tasks executed in a sandboxed shell environment.
Comparable with caveatNot comparable with Terminal-Bench 3.0 or 4.0 (different task sets) or v1; harness configuration (container, time limits) also shifts results.
2026-02
Google DeepMind model evaluation report (vendor, no tools; 51.4 with search+code)
Real GitHub issue resolution: does the model's patch pass the hidden tests.
Comparable with caveatPost-audit vendor claims and pre-audit scores sit on different task trust levels; scaffolding (agent harness, compute budget) also dominates results. Never aggregate across scaffolds.

Pricing tiers

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.

Gemini 3.1 Pro: $2/$12 per MTok (≤200K); $4/$18 (>200K). Still 'Preview' as of 2026-09-26; no Gemini 3.5 Pro or Gemini 4 release yet.

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.

FrontierRecord checked September 26, 2026

Gemini 3.1 Pro

Gemini 3.1 Pro is Google's only Pro model (still in Preview), with a 1M-token context and strong multimodal reasoning.

Best for

Very long documents
Multimodal reasoning
Frontier knowledge work

Watch out

Still in Preview; Google says Gemini 4 is in post-training but unreleased as of 2026-09-26, and newer Flash models outscore it on the Artificial Analysis index.

When the cheaper one wins

Gemini 3.1 Flash-Lite is cheaper on output at $1.50 per million tokens against $12 for Gemini 3.1 Pro — about 8.0×. 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: High

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 with differing scores — Measured on: Artificial Analysis Intelligence Index.
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.

Gemini 3.1 Flash-Lite: Gemini API pricing (gemini-3.1-flash-lite $0.25/$1.50) (accessed 2026-09-26)
Gemini 3.1 Flash-Lite: Gemini API — gemini-3.1-flash-lite model card (accessed 2026-09-26)
Gemini 3.1 Flash-Lite: Gemini API deprecations (earliest shutdown 2027-05-07) (accessed 2026-09-26)
Gemini 3.1 Pro: Google Cloud — Gemini 3.1 Pro (accessed 2026-08-29)
Gemini 3.1 Pro: TechCrunch — Gemini 3.1 Pro (accessed 2026-08-29)

Related comparisons

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

Common questions

Gemini 3.1 Flash-Lite vs Gemini 3.1 Pro

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

Is Gemini 3.1 Flash-Lite or Gemini 3.1 Pro cheaper for input?

Gemini 3.1 Flash-Lite is cheaper at $0.25 per million input tokens, against $2 for Gemini 3.1 Pro — roughly 8.0× 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 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. Gemini 3.1 Pro has tiered pricing: $2/$12 per MTok (≤200K); $4/$18 (>200K). Still 'Preview' as of 2026-09-26; no Gemini 3.5 Pro or Gemini 4 release yet.

Is Gemini 3.1 Flash-Lite or Gemini 3.1 Pro cheaper for output?

Gemini 3.1 Flash-Lite is cheaper at $1.50 per million output tokens, against $12 for Gemini 3.1 Pro — roughly 8.0× 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 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. Gemini 3.1 Pro has tiered pricing: $2/$12 per MTok (≤200K); $4/$18 (>200K). Still 'Preview' as of 2026-09-26; no Gemini 3.5 Pro or Gemini 4 release yet.

Which has the larger context window, Gemini 3.1 Flash-Lite or Gemini 3.1 Pro?

Both accept about 1.05M tokens of context, so document length will not decide between them.

Should I use Gemini 3.1 Flash-Lite or Gemini 3.1 Pro?

Gemini 3.1 Flash-Lite is the budget tier and Gemini 3.1 Pro the frontier 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 $2 for Gemini 3.1 Pro — a 8x difference at the headline tier.
Measured capability: Gemini 3.1 Pro leads Artificial Analysis Intelligence Index 29.7 to 15.6 (measured 2026-09-26).
Positioning: Gemini 3.1 Flash-Lite sits in the budget tier, Gemini 3.1 Pro in the frontier tier — most production volume (classification, extraction, summarisation) does not need the pricier tier.

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