Pairwise benchmark snapshot · Aug 16, 2026noindex (thin pair)

Claude Opus 4.8 vs Google: Gemini 3.1 Pro Preview Custom Tools benchmark

Name: Claude Opus 4.8 vs Google: Gemini 3.1 Pro Preview Custom Tools AI benchmark comparison
Creator: CompareLLM
License: https://creativecommons.org/licenses/by/4.0/

This page compares Claude Opus 4.8 (Anthropic) and Google: Gemini 3.1 Pro Preview Custom Tools (Google) using the latest snapshots we have as of Aug 16, 2026. Google: Gemini 3.1 Pro Preview Custom Tools wins on output price at $12/1M. Google: Gemini 3.1 Pro Preview Custom Tools has the larger context window (1M tokens). Every cell below is a dated snapshot from a named public source — we do not invent missing scores, and we do not run SWE-bench ourselves.

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Anthropic

Claude Opus 4.8

Prior Opus generation still billed at $5/$25. Kept as a compare baseline against Opus 5.

Elo 1,598$25/1M out

Google

Google: Gemini 3.1 Pro Preview Custom Tools

Auto-discovered from OpenRouter (google/gemini-3.1-pro-preview-customtools). Preview until a second source matches.

$12/1M out

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Model B

Quick vs:vs Claude Opus 4.5 vs Claude Opus 4.6 vs Claude Sonnet 4.5 vs Claude 3.7 Sonnet

Interactive Comparison Diagram

Matchup Breakdown

Tug-of-War Matchup Matrix

Category wins across intelligence, speed, and pricing efficiency.

Claude Opus 4.8 (7)vsGoogle: Gemini 3.1 Pro Preview Custom Tools (3)

Claude Opus 4.8: 7W (70%)Overall: Claude Opus 4.8Google: Gemini 3.1 Pro Preview Custom Tools: 3W (30%)

← Claude Opus 4.8Google: Gemini 3.1 Pro Preview Custom Tools →

Claude Opus 4.8 (5/5)

Intelligence & Reasoning

Preference Elo, Coding proficiency, SWE-bench & LiveBench accuracy

Preference Elo

1,598vs—

Coding Elo

1,604vs—

SWE-bench

78.4%vs—

LiveBench

73.6%vs—

GPQA Diamond

86.2%vs—

Claude Opus 4.8: 5WGoogle: Gemini 3.1 Pro Preview Custom Tools: 0W

Claude Opus 4.8 (2/2)

Speed & Latency

Generation throughput and time to first token responsiveness

Output speed

66 tok/svs—

Time to first token

330 msvs—

Claude Opus 4.8: 2WGoogle: Gemini 3.1 Pro Preview Custom Tools: 0W

Google: Gemini 3.1 Pro Preview Custom Tools (3/3)

Pricing & Capacity

Cost per million tokens and max context window length

Output price

$25/1Mvs$12/1M

Input price

$5/1Mvs$2/1M

Context window

1Mvs1M

Claude Opus 4.8: 0WGoogle: Gemini 3.1 Pro Preview Custom Tools: 3W

Capability Matchup Radar

Multi-Dimensional Capability Radar

Each spoke is a skill. Farther from the center is better (0–100th percentile). Tap any dot to inspect details.

Tap any node to inspect

Percentile 0–100

Dimensional AdvantageClaude Opus 4.8 4/6

Preference Elo

No shared data

Throughput Speed

No shared data

Price Efficiency

Google: Gemini 3.1 Pro Preview Custom Tools

$13.00/1M cheaper

Full Benchmark Score Matrix

—

Elo

High is better

1,598

EloHigh is better

—

Code Elo

High is better

1,604

Code EloHigh is better

—

LiveBench

High is better

73.6%

LiveBenchHigh is better

—

SWE-bench

High is better

78.4%

SWE-benchHigh is better

—

GPQA

High is better

86.2%

GPQAHigh is better

—

TTFT

Low is better

330 ms

TTFTLow is better

—

Speed

High is better

66 tok/s

SpeedHigh is better

—

In $

Low is better

$5/1M

In $Low is better

$2/1M+150%

Out $

Low is better

$25/1M

Out $Low is better

$12/1M+108%

Context

High is better

ContextHigh is better

1M+5%

Interactive Simulator

Workload Cost & Savings Calculator

Simulate monthly production API costs based on published $/1M tokens.

Save up to 55% with Google: Gemini 3.1 Pro Preview Custom Tools

Monthly Volume50M tokens/mo

Quick Presets:

Token Ratio (In vs Out)70% In / 30% Out

RAG / Search (10% out)Coding / Chat (50% out)

Claude Opus 4.8$550.00 / mo

In: $175.00Out: $375.00

Google: Gemini 3.1 Pro Preview Custom Tools$250.00 / mo

In: $70.00Out: $180.00

Estimated Cost Delta

Google: Gemini 3.1 Pro Preview Custom Tools is estimated to save $300.00/month ($3,600/year).

Based on 50M tokens (30% gen)

Key Selection Recommendations

1
Google: Gemini 3.1 Pro Preview Custom Tools:Pick Google: Gemini 3.1 Pro Preview Custom Tools when you are optimizing output cost.
2
Google: Gemini 3.1 Pro Preview Custom Tools:Pick Google: Gemini 3.1 Pro Preview Custom Tools for million-token RAG or long-document jobs.

Recommended Workload Routing

Repo / coding agentsinsufficient data

Need SWE-bench on both sides.

High-volume chatGoogle: Gemini 3.1 Pro Preview Custom Tools

Lower output list price ($12/1M).

Voice / low-latency UIinsufficient data

Need TTFT on both sides.

Long-document RAGGoogle: Gemini 3.1 Pro Preview Custom Tools

Larger window (1M).

Screenshots / visionClaude Opus 4.8

Claude Opus 4.8 is the side marked multimodal in the catalog.

Target Workload	Recommended Pick	Evaluation Rationale
Repo / coding agents	insufficient data	Need SWE-bench on both sides.
High-volume chat	Google: Gemini 3.1 Pro Preview Custom Tools	Lower output list price ($12/1M).
Voice / low-latency UI	insufficient data	Need TTFT on both sides.
Long-document RAG	Google: Gemini 3.1 Pro Preview Custom Tools	Larger window (1M).
Screenshots / vision	Claude Opus 4.8	Claude Opus 4.8 is the side marked multimodal in the catalog.

Related Editorial Dispatches & Benchmark Notes

View all news

launchJun 20, 2026

Keep Opus 4.8 on the board: a baseline, not a flagship

Opus 4.8 still bills $5/$25. We keep it so Opus 5 vs 4.8 is a real generation delta, not marketing.

Community Sentiment

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LIVE

Anthropic

Claude Opus 4.8

Elo 1,598

LiveBench73.6%

SWE-bench78.4%

Speed66 tok/s

Output cost$25/1M

Google

Google: Gemini 3.1 Pro Preview Custom Tools

Elo n/a

LiveBench—

SWE-bench—

Speed—

Output cost$12/1M

Frequently Asked Questions

Which is better overall, Claude Opus 4.8 or Google: Gemini 3.1 Pro Preview Custom Tools?: We do not have preference Elo for both models, so we do not declare an overall winner. Compare the metrics that exist.
Which is better at coding, Claude Opus 4.8 or Google: Gemini 3.1 Pro Preview Custom Tools?: SWE-bench is missing for at least one model, so we do not rank coding from a single number.
Which is cheaper to run in production?: Google: Gemini 3.1 Pro Preview Custom Tools output tokens are $12/1M versus $25/1M. Input prices and retry rates still move the real bill.
Which is faster, Claude Opus 4.8 or Google: Gemini 3.1 Pro Preview Custom Tools?: We do not have TTFT for both models.
Which has the larger context window?: Google: Gemini 3.1 Pro Preview Custom Tools accepts 1M tokens versus 1M.
Can I self-host either model?: Neither model is marked open-weights here. You are comparing hosted APIs.
Are these scores from CompareLLM’s own evals?: No. V1 aggregates public leaderboards (and optional first-party latency pings). Each cell names its source and date. Read /methodology.
What does preference Elo mean on this page?: Preference Elo is a crowd vote from LMArena / Arena. People see two hidden answers and pick the one they like more. The model that wins more often gets a higher Elo. That means people preferred it — not that it passed a school test. It is not SWE-bench, not accuracy, and not a number we invent. Claude Opus 4.8 and Google: Gemini 3.1 Pro Preview Custom Tools Elo cells are dated snapshots from the named source — we do not compute Arena ourselves.

Similar Head-to-Head Comparisons

All Claude Opus 4.8 matchups →|All Google: Gemini 3.1 Pro Preview Custom Tools matchups →

Claude Opus 4.8 vs Claude Opus 4.6 (previous opus)Claude Opus 4.8 vs Claude Opus 5 (next opus)Claude Fable 5 vs Claude Opus 4.8 Gemini 3.6 Pro vs Claude Opus 4.8 Claude Opus 4.5 vs Claude Opus 4.8 Claude Sonnet 5 vs Claude Opus 4.8

Claude Opus 4.8 vs Google: Gemini 3.1 Pro Preview Custom Tools benchmark

Interactive Comparison Diagram

Matchup Breakdown

Tug-of-War Matchup Matrix

Category wins across intelligence, speed, and pricing efficiency.

Claude Opus 4.8 (7)vsGoogle: Gemini 3.1 Pro Preview Custom Tools (3)

Claude Opus 4.8: 7W (70%)Overall: Claude Opus 4.8Google: Gemini 3.1 Pro Preview Custom Tools: 3W (30%)

← Claude Opus 4.8Google: Gemini 3.1 Pro Preview Custom Tools →

Claude Opus 4.8 (5/5)

Intelligence & Reasoning

Preference Elo, Coding proficiency, SWE-bench & LiveBench accuracy

Preference Elo

1,598vs—

Coding Elo

1,604vs—

SWE-bench

78.4%vs—

LiveBench

73.6%vs—

GPQA Diamond

86.2%vs—

Claude Opus 4.8: 5WGoogle: Gemini 3.1 Pro Preview Custom Tools: 0W

Claude Opus 4.8 (2/2)

Speed & Latency

Generation throughput and time to first token responsiveness

Output speed

66 tok/svs—

Time to first token

330 msvs—

Claude Opus 4.8: 2WGoogle: Gemini 3.1 Pro Preview Custom Tools: 0W

Google: Gemini 3.1 Pro Preview Custom Tools (3/3)

Pricing & Capacity

Cost per million tokens and max context window length

Output price

$25/1Mvs$12/1M

Input price

$5/1Mvs$2/1M

Context window

1Mvs1M

Claude Opus 4.8: 0WGoogle: Gemini 3.1 Pro Preview Custom Tools: 3W

Recommended Workload Routing

Repo / coding agentsinsufficient data

Need SWE-bench on both sides.

High-volume chatGoogle: Gemini 3.1 Pro Preview Custom Tools

Lower output list price ($12/1M).

Voice / low-latency UIinsufficient data

Need TTFT on both sides.

Long-document RAGGoogle: Gemini 3.1 Pro Preview Custom Tools

Larger window (1M).

Screenshots / visionClaude Opus 4.8

Claude Opus 4.8 is the side marked multimodal in the catalog.

Target Workload	Recommended Pick	Evaluation Rationale
Repo / coding agents	insufficient data	Need SWE-bench on both sides.
High-volume chat	Google: Gemini 3.1 Pro Preview Custom Tools	Lower output list price ($12/1M).
Voice / low-latency UI	insufficient data	Need TTFT on both sides.
Long-document RAG	Google: Gemini 3.1 Pro Preview Custom Tools	Larger window (1M).
Screenshots / vision	Claude Opus 4.8	Claude Opus 4.8 is the side marked multimodal in the catalog.

Frequently Asked Questions

Which is better overall, Claude Opus 4.8 or Google: Gemini 3.1 Pro Preview Custom Tools?

We do not have preference Elo for both models, so we do not declare an overall winner. Compare the metrics that exist.

Which is better at coding, Claude Opus 4.8 or Google: Gemini 3.1 Pro Preview Custom Tools?

SWE-bench is missing for at least one model, so we do not rank coding from a single number.

Which is cheaper to run in production?

Google: Gemini 3.1 Pro Preview Custom Tools output tokens are $12/1M versus $25/1M. Input prices and retry rates still move the real bill.

Which is faster, Claude Opus 4.8 or Google: Gemini 3.1 Pro Preview Custom Tools?

We do not have TTFT for both models.

Which has the larger context window?

Google: Gemini 3.1 Pro Preview Custom Tools accepts 1M tokens versus 1M.

Can I self-host either model?

Neither model is marked open-weights here. You are comparing hosted APIs.

Are these scores from CompareLLM’s own evals?

No. V1 aggregates public leaderboards (and optional first-party latency pings). Each cell names its source and date. Read /methodology.

What does preference Elo mean on this page?

Preference Elo is a crowd vote from LMArena / Arena. People see two hidden answers and pick the one they like more. The model that wins more often gets a higher Elo. That means people preferred it — not that it passed a school test. It is not SWE-bench, not accuracy, and not a number we invent. Claude Opus 4.8 and Google: Gemini 3.1 Pro Preview Custom Tools Elo cells are dated snapshots from the named source — we do not compute Arena ourselves.

Swap or Add Any Model to this Matchup

Interactive Comparison Diagram

Tug-of-War Matchup Matrix

Intelligence & Reasoning

Speed & Latency

Pricing & Capacity

Multi-Dimensional Capability Radar

No shared data

No shared data

Google: Gemini 3.1 Pro Preview Custom Tools

Full Benchmark Score Matrix

Workload Cost & Savings Calculator

Key Selection Recommendations

Recommended Workload Routing

Related Editorial Dispatches & Benchmark Notes

Keep Opus 4.8 on the board: a baseline, not a flagship

Cast Your Matchup Vote

Community Discussions (0)

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CompareLLM Matrix

Claude Opus 4.8

Google: Gemini 3.1 Pro Preview Custom Tools

Frequently Asked Questions

Related news

Similar Head-to-Head Comparisons

Swap or Add Any Model to this Matchup

Interactive Comparison Diagram

Tug-of-War Matchup Matrix

Intelligence & Reasoning

Speed & Latency

Pricing & Capacity

Multi-Dimensional Capability Radar

No shared data

No shared data

Google: Gemini 3.1 Pro Preview Custom Tools

Full Benchmark Score Matrix

Workload Cost & Savings Calculator

Key Selection Recommendations

Recommended Workload Routing

Related Editorial Dispatches & Benchmark Notes

Keep Opus 4.8 on the board: a baseline, not a flagship

Cast Your Matchup Vote

Community Discussions (0)

Share card

CompareLLM Matrix

Claude Opus 4.8

Google: Gemini 3.1 Pro Preview Custom Tools

Frequently Asked Questions

Related news

Similar Head-to-Head Comparisons