Model comparison · accepted catalogue facts 2026-10-21
Claude Fable 5 vs Gemini 3.1 Pro Preview
A quality score or a computable price is missing. This pair has no better-and-cheaper verdict.
Editorial comparison: Cross-provider head-to-head: Claude Fable 5 (Anthropic) vs Gemini 3.1 Pro Preview (Google) on intelligence, speed, and pricing Inclusion does not recommend either model.
Balanced effective USD / 1M tokens · lower is better
Unknown
In-Depth Analysis
Claude Fable 5 vs Gemini 3.1 Pro Preview: Measured Technical Breakdown
Comprehensive comparison across measured human-preference evaluation, effective production token costs, architectural limits, and migration trade-offs.
Measured Capability (LMArena)
Claude Fable 5 leads by 10.7 Elo
Claude Fable 5: 1491 ±4.3 · Gemini 3.1 Pro Preview: 1480.3 ±2.95 Statistically significant preference separation
Cost Comparison Across Canonical Production Workloads
Rates represent effective cost per 1M tokens under standard token blends. Cached prompt reads are factored according to workload context reuse.
Workload & Ratio
Claude Fable 5
Gemini 3.1 Pro Preview
Cost Difference
Advantage
Balanced3 tokens in per 1 out
$20.00/1M tokens
Separately billed reasoning tokens are not part of this token blend.
—
Custom quote needed
SummariseHuge input, tiny output
$9.44/1M tokens
Separately billed reasoning tokens are not part of this token blend.
—
Custom quote needed
ChatLong cached system prompt
$23.30/1M tokens
Separately billed reasoning tokens are not part of this token blend.
—
Custom quote needed
Code genOutput dominates
$33.28/1M tokens
Separately billed reasoning tokens are not part of this token blend.
—
Custom quote needed
AgenticContext replayed each turn
$10.65/1M tokens
Separately billed reasoning tokens are not part of this token blend.
—
Custom quote needed
Architectural & Operational Specifications
Specification
Claude Fable 5
Gemini 3.1 Pro Preview
Operational Note
Context window
1,000,000 tokens
1,048,576 tokens
—
Max output generation
128,000 tokens
65,536 tokens
Claude Fable 5 allows longer single-turn completions
Base input price
$10.00 / 1M tokens
$2.00 / 1M tokens
Gemini 3.1 Pro Preview input rate is cheaper
Base output price
$50.00 / 1M tokens
$12.00 / 1M tokens
Gemini 3.1 Pro Preview output rate is cheaper
Cached input price
$1.00 / 1M tokens
$0.200 / 1M tokens
Gemini 3.1 Pro Preview offers lower cached prompt cost
Reasoning & thinking tokens
Supported; standard rates
Supported; separately billed at $12.00/1M
—
Input modalities
text, image, file
audio, file, image, text, video
—
Tool calling / function use
Supported
Supported
—
Open weights & licence
Proprietary (proprietary)
Proprietary (proprietary)
—
Provider & reseller market
Anthropic · 6 provider offers
Google · 6 provider offers
—
When to Choose Claude Fable 5
Higher measured general capability (1491 Elo on human evaluation).
Higher maximum completion limit (128,000 tokens).
Direct integration with Anthropic tooling and API features.
Risks when moving from Gemini 3.1 Pro Preview → Claude Fable 5:
Context window: 1,048,576 → 1,000,000 tokens.
audio input is not supported by the candidate.
video input is not supported by the candidate.
When to Choose Gemini 3.1 Pro Preview
Larger context window (1,048,576 tokens) for long-document or repo-level context.
These settings are included in the share link. The fixed-request scenario and private evaluation data below are excluded.
A ↔ B
A quality score or a computable price is missing. This pair has no better-and-cheaper verdict.
Estimated blend: 75% input, 25% output; 0% cached input. Base context tier. Prompt length selects the billing tier. An unlisted cache-read rate uses that tier’s full input rate in this blend; missing required input or output rates prevent an estimate. The fixed-request estimate below validates actual context and output limits and requires a published cache-read rate when cache hits are assumed.
What changes between these models
Quality first, then estimated price. LMArena scores are human-preference measurements, not a benchmark of your application. A missing score is unrated.
Claude Fable 5 · Meets the stated model requirements
Gemini 3.1 Pro Preview · Meets the stated model requirements
Material differences and unknown evidence. Deltas compare each model with model A. Unknown facts remain visible.
Provider counts and precision flags describe catalogue offers. They do not establish the precision, availability, region, tool behaviour or limits of your chosen endpoint. Open each model’s provider table before switching.
Estimate unavailable: Separately billed reasoning tokens are not part of this token blend.
Separate reasoning: $12/1M tokens; reasoning-token counts are not modelled here. Rates below are USD per 1M tokens. A threshold selects that whole input/output rate pair.
Input-token threshold
Input
Output
Cached input
Base, up to and including first threshold
$2
$12
$0.2
> 200,000
$4
$18
$0.4
Migration preflight · compare each candidate with model A
Keeping Claude Fable 5 is a valid decision. No pairwise comparison certifies a drop-in replacement.
Claude Fable 5 → Gemini 3.1 Pro Preview
Known loss or failed requirement
Output limit: 128,000 → 65,536 tokens.
Provider endpoint, serving precision, availability and task success need your own verification. Catalogue model capabilities do not certify an endpoint.
Private to this tab unless you save locally or explicitly export private details. These are estimates, not observed invoices. Cross-model token counts and task success are assumptions.
0.1 extra attempts means 10 extra full attempts per 100 requests. Cache writes, tool charges, taxes and unlisted charges are excluded.
Claude Fable 5Estimated total: $45 1,000 full attempts · base rates
Gemini 3.1 Pro PreviewEstimated total: unknown Separately billed reasoning tokens are not part of this request shape.
Prompt and output sensitivity · sampled scenarios
Every point recalculates the entire request shape. Tier-boundary samples include one token below, at and above each threshold. Ordering between samples is not guaranteed. Lowest known cost excludes unknown estimates and is not a replacement recommendation.
Vary input; hold output, requests, cache and retries fixed.
Input tokens
Claude Fable 5
Gemini 3.1 Pro Preview
Coverage
2,000
$45Lowest known
unknownSeparately billed reasoning tokens are not part of this request shape.
Incomplete
4,096
$65.96Lowest known
unknownSeparately billed reasoning tokens are not part of this request shape.
Incomplete
32,768
$352.68Lowest known
unknownSeparately billed reasoning tokens are not part of this request shape.
Incomplete
131,072
$1,335.72Lowest known
unknownSeparately billed reasoning tokens are not part of this request shape.
Incomplete
199,999
$2,024.99Lowest known
unknownSeparately billed reasoning tokens are not part of this request shape.
Incomplete
200,000
$2,025Lowest known
unknownSeparately billed reasoning tokens are not part of this request shape.
Incomplete
200,001
$2,025.01Lowest known
unknownSeparately billed reasoning tokens are not part of this request shape.
Incomplete
Vary output; hold input, requests, cache and retries fixed.
Output tokens
Claude Fable 5
Gemini 3.1 Pro Preview
128
$26.4
unknownSeparately billed reasoning tokens are not part of this request shape.
2,048
$122.4
unknownSeparately billed reasoning tokens are not part of this request shape.
8,192
$429.6
unknownSeparately billed reasoning tokens are not part of this request shape.
Bring your observed evaluation results
JSON is parsed locally. Prompts, filenames, individual responses and extra fields are not retained. Import only aggregate measurements for selected models. Task/version labels do not establish that two evaluations used the same dataset.
Use the exact catalogue ID. Replace the example values with observed measurements. Omit costUsd or latencyMs when they are unknown. No public score is inferred from these observations.
Keep the decision and its evidence
A portable record retains selected facts, complete tier ladders, public requirements and the publication manifest. It also embeds the full permitted public catalogue to verify the input artifact checksum. Files are larger for this reason (up to 2 MB); local storage is limited to 12 records. Team review is local to this browser; there is no hosted collaboration.
Saving is opt-in and includes private review fields. Shared comparison links never include them. Version 1 Check references remain separate and are not overwritten or guessed into this format.
Saved local decisions · 0
No version 2 decision records are stored in this browser.
Questions this page answers
Is Claude Fable 5 a better-and-cheaper replacement for Gemini 3.1 Pro Preview?
A quality score or a computable price is missing. This pair has no better-and-cheaper verdict.
Which model is higher rated: Claude Fable 5 or Gemini 3.1 Pro Preview?
Claude Fable 5 scores higher on LMArena general (1491.0 ±4.3) compared to Gemini 3.1 Pro Preview (1480.3 ±3.0), a margin of 10.7 Elo points. The measured confidence intervals do not overlap, demonstrating a statistically significant preference lead on human evaluations.
Which model is more cost-effective: Claude Fable 5 or Gemini 3.1 Pro Preview?
Gemini 3.1 Pro Preview bills reasoning tokens separately. Direct pricing comparison requires evaluating your specific input/output prompt ratios and reasoning settings.
How do their context windows and generation limits compare?
Claude Fable 5 provides a 1,000,000-token context window with a maximum output limit of 128,000 tokens. Gemini 3.1 Pro Preview provides a 1,048,576-token context window with a maximum output of 65,536 tokens.
What capabilities are lost when switching between Claude Fable 5 and Gemini 3.1 Pro Preview?
Switching from Claude Fable 5 to Gemini 3.1 Pro Preview involves: Output limit: 128,000 → 65,536 tokens. Conversely, moving from Gemini 3.1 Pro Preview to Claude Fable 5 involves: Context window: 1,048,576 → 1,000,000 tokens; audio input is not supported by the candidate; video input is not supported by the candidate. Run test suites on your specific prompt templates and tool declarations before cutting over production traffic.
Can Claude Fable 5 or Gemini 3.1 Pro Preview be self-hosted or deployed privately?
Both Claude Fable 5 and Gemini 3.1 Pro Preview are proprietary cloud models offered via managed API endpoints. Claude Fable 5 is served by Anthropic and 6 catalogue offers, while Gemini 3.1 Pro Preview is served by Google and 6 catalogue offers.
What is included in this comparison?
Accepted model capabilities, context and output limits, complete price-tier ladders, independent LMArena measurements and missing evidence. Provider endpoint precision and application success still need verification.
Can I compare a different workload or keep a decision record?
Yes. Change the public workload, prompt length and requirements in the comparison workspace. Fixed-request scenarios, aggregate evaluations and review notes stay local unless explicitly exported.
