Pairwise benchmark snapshot · Aug 16, 2026

Gemini 1.5 Pro vs Gemini 3 Flash benchmark

Name: Gemini 1.5 Pro vs Gemini 3 Flash AI benchmark comparison
Creator: CompareLLM
License: https://creativecommons.org/licenses/by/4.0/

This page compares Gemini 1.5 Pro (Google) and Gemini 3 Flash (Google) using the latest snapshots we have as of Aug 16, 2026. On preference Elo, Gemini 3 Flash is ahead by 235 points (1,495 vs 1,260; seed-bootstrap (Aug 1, 2026)). On SWE-bench coding, Gemini 3 Flash resolves 75.8% versus 38% (seed-bootstrap (Aug 1, 2026)). Gemini 3 Flash streams faster (190 tok/s) while Gemini 3 Flash is the cheaper output token ($3/1M). Gemini 1.5 Pro has the larger context window (2M 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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Google

Gemini 1.5 Pro

First million-token Gemini Pro. Baseline for 1.5 vs 2.5 vs 3.x Pro.

Elo 1,260$5/1M out

Google

Gemini 3 Flash

Fast Google frontier-adjacent model. Near-top official SWE-bench at a fraction of Opus price.

Elo 1,495$3/1M out

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Model A

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.

Gemini 1.5 Pro (1)vsGemini 3 Flash (9)

Gemini 1.5 Pro: 1W (10%)Overall: Gemini 3 FlashGemini 3 Flash: 9W (90%)

← Gemini 1.5 ProGemini 3 Flash →

Gemini 3 Flash (5/5)

Intelligence & Reasoning

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

Preference Elo

1,260vs1,495

Coding Elo

—vs1,510

SWE-bench

38%vs75.8%

LiveBench

49.2%vs66.8%

GPQA Diamond

58%vs78.4%

Gemini 1.5 Pro: 0WGemini 3 Flash: 5W

Gemini 3 Flash (2/2)

Speed & Latency

Generation throughput and time to first token responsiveness

Output speed

70 tok/svs190 tok/s

Time to first token

240 msvs95 ms

Gemini 1.5 Pro: 0WGemini 3 Flash: 2W

Gemini 3 Flash (2/3)

Pricing & Capacity

Cost per million tokens and max context window length

Output price

$5/1Mvs$3/1M

Input price

$1.25/1Mvs$0.5/1M

Context window

2Mvs1M

Gemini 1.5 Pro: 1WGemini 3 Flash: 2W

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 AdvantageGemini 3 Flash 5/6

Preference Elo

Gemini 3 Flash

235 pts advantage

Throughput Speed

Gemini 3 Flash

120 tok/s faster

Price Efficiency

Gemini 3 Flash

$2.00/1M cheaper

Full Benchmark Score Matrix

—

Elo

High is better

1,260

EloHigh is better

1,495+19%

Code Elo

High is better

—

Code EloHigh is better

1,510

LiveBench

High is better

49.2%

LiveBenchHigh is better

66.8%+36%

SWE-bench

High is better

38%

SWE-benchHigh is better

75.8%+99%

GPQA

High is better

58%

GPQAHigh is better

78.4%+35%

TTFT

Low is better

240 ms

TTFTLow is better

95 ms+153%

Speed

High is better

70 tok/s

SpeedHigh is better

190 tok/s+171%

In $

Low is better

$1.25/1M

In $Low is better

$0.5/1M+150%

Out $

Low is better

$5/1M

Out $Low is better

$3/1M+67%

Context

High is better

+91%2M

ContextHigh is better

Interactive Simulator

Workload Cost & Savings Calculator

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

Save up to 47% with Gemini 3 Flash

Monthly Volume50M tokens/mo

Quick Presets:

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

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

Gemini 1.5 Pro$118.75 / mo

In: $43.75Out: $75.00

Gemini 3 Flash$62.50 / mo

In: $17.50Out: $45.00

Estimated Cost Delta

Gemini 3 Flash is estimated to save $56.25/month ($675/year).

Based on 50M tokens (30% gen)

Key Selection Recommendations

1
Gemini 3 Flash:Pick Gemini 3 Flash when repo-level coding accuracy is the constraint.
2
Gemini 3 Flash:Pick Gemini 3 Flash when time-to-first-token matters more than peak Elo.
3
Gemini 1.5 Pro:Pick Gemini 1.5 Pro for million-token RAG or long-document jobs.

Recommended Workload Routing

Repo / coding agentsGemini 3 Flash

Higher SWE-bench (75.8%).

High-volume chatGemini 3 Flash

Lower output list price ($3/1M).

Voice / low-latency UIGemini 3 Flash

Lower TTFT (95 ms).

Long-document RAGGemini 1.5 Pro

Larger window (2M).

Screenshots / visionGemini 3 Flash

Both accept images. Defaulting to the higher-Elo side (Gemini 3 Flash).

Target Workload	Recommended Pick	Evaluation Rationale
Repo / coding agents	Gemini 3 Flash	Higher SWE-bench (75.8%).
High-volume chat	Gemini 3 Flash	Lower output list price ($3/1M).
Voice / low-latency UI	Gemini 3 Flash	Lower TTFT (95 ms).
Long-document RAG	Gemini 1.5 Pro	Larger window (2M).
Screenshots / vision	Gemini 3 Flash	Both accept images. Defaulting to the higher-Elo side (Gemini 3 Flash).

Related Editorial Dispatches & Benchmark Notes

View all news

launchMar 16, 2026

Gemini 3 Flash: near-top official SWE-bench at a fraction of Opus

March 2026 speed SKU. Still a useful cheap-coding compare even after 3.6/3.7 Flash.

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LIVE

Google

Gemini 1.5 Pro

Elo 1,260

LiveBench49.2%

SWE-bench38%

Speed70 tok/s

Output cost$5/1M

Google

Gemini 3 Flash

Elo 1,495

LiveBench66.8%

SWE-bench75.8%

Speed190 tok/s

Output cost$3/1M

Frequently Asked Questions

Which is better overall, Gemini 1.5 Pro or Gemini 3 Flash?: Gemini 3 Flash has the higher preference Elo in our latest snapshot (1,495). “Better” still depends on coding, price, and latency — see the table.
Which is better at coding, Gemini 1.5 Pro or Gemini 3 Flash?: Gemini 3 Flash leads SWE-bench at 75.8% vs 38%. SWE-bench is one harness, not your repo.
Which is cheaper to run in production?: Gemini 3 Flash output tokens are $3/1M versus $5/1M. Input prices and retry rates still move the real bill.
Which is faster, Gemini 1.5 Pro or Gemini 3 Flash?: Gemini 3 Flash has the lower time-to-first-token (95 ms vs 240 ms). Tokens/sec is a separate column if you care about long completions.
Which has the larger context window?: Gemini 1.5 Pro accepts 2M 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. Gemini 1.5 Pro and Gemini 3 Flash Elo cells are dated snapshots from the named source — we do not compute Arena ourselves.

Similar Head-to-Head Comparisons

All Gemini 1.5 Pro matchups →|All Gemini 3 Flash matchups →

Gemini 1.5 Pro vs Gemini 2.5 Pro (next gemini-pro)Gemini 3 Flash vs Gemini 2.5 Flash (previous gemini-flash)Gemini 3 Flash vs Gemini 3.6 Flash (next gemini-flash)Gemini 3 Pro vs Gemini 3 Flash Gemini 2.0 Flash Thinking vs Gemini 3 Flash Gemini 3.6 Pro vs Gemini 3 Flash

Gemini 1.5 Pro vs Gemini 3 Flash benchmark

Interactive Comparison Diagram

Matchup Breakdown

Tug-of-War Matchup Matrix

Category wins across intelligence, speed, and pricing efficiency.

Gemini 1.5 Pro (1)vsGemini 3 Flash (9)

Gemini 1.5 Pro: 1W (10%)Overall: Gemini 3 FlashGemini 3 Flash: 9W (90%)

← Gemini 1.5 ProGemini 3 Flash →

Gemini 3 Flash (5/5)

Intelligence & Reasoning

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

Preference Elo

1,260vs1,495

Coding Elo

—vs1,510

SWE-bench

38%vs75.8%

LiveBench

49.2%vs66.8%

GPQA Diamond

58%vs78.4%

Gemini 1.5 Pro: 0WGemini 3 Flash: 5W

Gemini 3 Flash (2/2)

Speed & Latency

Generation throughput and time to first token responsiveness

Output speed

70 tok/svs190 tok/s

Time to first token

240 msvs95 ms

Gemini 1.5 Pro: 0WGemini 3 Flash: 2W

Gemini 3 Flash (2/3)

Pricing & Capacity

Cost per million tokens and max context window length

Output price

$5/1Mvs$3/1M

Input price

$1.25/1Mvs$0.5/1M

Context window

2Mvs1M

Gemini 1.5 Pro: 1WGemini 3 Flash: 2W

Recommended Workload Routing

Repo / coding agentsGemini 3 Flash

Higher SWE-bench (75.8%).

High-volume chatGemini 3 Flash

Lower output list price ($3/1M).

Voice / low-latency UIGemini 3 Flash

Lower TTFT (95 ms).

Long-document RAGGemini 1.5 Pro

Larger window (2M).

Screenshots / visionGemini 3 Flash

Both accept images. Defaulting to the higher-Elo side (Gemini 3 Flash).

Target Workload	Recommended Pick	Evaluation Rationale
Repo / coding agents	Gemini 3 Flash	Higher SWE-bench (75.8%).
High-volume chat	Gemini 3 Flash	Lower output list price ($3/1M).
Voice / low-latency UI	Gemini 3 Flash	Lower TTFT (95 ms).
Long-document RAG	Gemini 1.5 Pro	Larger window (2M).
Screenshots / vision	Gemini 3 Flash	Both accept images. Defaulting to the higher-Elo side (Gemini 3 Flash).

Frequently Asked Questions

Which is better overall, Gemini 1.5 Pro or Gemini 3 Flash?

Gemini 3 Flash has the higher preference Elo in our latest snapshot (1,495). “Better” still depends on coding, price, and latency — see the table.

Which is better at coding, Gemini 1.5 Pro or Gemini 3 Flash?

Gemini 3 Flash leads SWE-bench at 75.8% vs 38%. SWE-bench is one harness, not your repo.

Which is cheaper to run in production?

Gemini 3 Flash output tokens are $3/1M versus $5/1M. Input prices and retry rates still move the real bill.

Which is faster, Gemini 1.5 Pro or Gemini 3 Flash?

Gemini 3 Flash has the lower time-to-first-token (95 ms vs 240 ms). Tokens/sec is a separate column if you care about long completions.

Which has the larger context window?

Gemini 1.5 Pro accepts 2M 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. Gemini 1.5 Pro and Gemini 3 Flash 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

Gemini 3 Flash

Gemini 3 Flash

Gemini 3 Flash

Full Benchmark Score Matrix

Workload Cost & Savings Calculator

Key Selection Recommendations

Recommended Workload Routing

Related Editorial Dispatches & Benchmark Notes

Gemini 3 Flash: near-top official SWE-bench at a fraction of Opus

Cast Your Matchup Vote

Community Discussions (0)

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CompareLLM Matrix

Gemini 1.5 Pro

Gemini 3 Flash

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

Gemini 3 Flash

Gemini 3 Flash

Gemini 3 Flash

Full Benchmark Score Matrix

Workload Cost & Savings Calculator

Key Selection Recommendations

Recommended Workload Routing

Related Editorial Dispatches & Benchmark Notes

Gemini 3 Flash: near-top official SWE-bench at a fraction of Opus

Cast Your Matchup Vote

Community Discussions (0)

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CompareLLM Matrix

Gemini 1.5 Pro

Gemini 3 Flash

Frequently Asked Questions

Related news

Similar Head-to-Head Comparisons