Claude Opus 5 vs Gemini 3.6 Flash

Anthropic · US  |  Google · US · Updated June 2026

Quick verdict

Pick Claude Opus 5 for frontier reasoning at lower cost per task — anthropic reports it more than doubling opus 4.8 on frontier-bench v0.1 or agentic coding — within 0.5% of fable 5's peak cursorbench 3.2 score at half the cost per task (anthropic's figures). Pick Gemini 3.6 Flash for high-volume, cost-sensitive work — google says it uses about 17% fewer output tokens than 3.5 flash or multimodal input across text, image and video at a 1m-token window. On a tight budget at scale, Gemini 3.6 Flash is the value pick.

Claude Opus 5 (Anthropic) and Gemini 3.6 Flash (Google) are two of the models people most often weigh against each other in 2026. Claude Opus 5 is anthropic's July 2026 flagship at $5/$25 with a 1M window and an effort dial — near-frontier quality pitched on cost per task, not raw peak. Gemini 3.6 Flash is google's July 2026 workhorse Flash model at $1.50/$7.50 with a 1M window — tuned for cheap, high-volume multimodal work over benchmark peaks. They diverge most on price and context window — each quantified below from the models' real specs.

Key differences at a glance

Side-by-side specs

SpecClaude Opus 5Gemini 3.6 Flash
ProviderAnthropic (US) Google (US)
ReleasedJuly 24, 2026 July 21, 2026
Context window1M (~1,500 pages) 1M (~1,573 pages)
Price (in/out)$5/$25 per 1M tokens $1.5/$7.5 per 1M tokens
Open weight?No — API only No — API only
Modalitiestext, image, code text, image, video, code
SWE-Bench VerifiedNot published Not published
MRCR v2 @ 1MNot published Not published

Who wins what

Frontier reasoning at lower cost per task — Anthropic reports it more than doubling Opus 4.8 on Frontier-Bench v0.1

Claude Opus 5

Gemini 3.6 Flash is comparatively weak here — a Flash-tier model — not built to top reasoning or coding leaderboards against flagships

Agentic coding — within 0.5% of Fable 5's peak CursorBench 3.2 score at half the cost per task (Anthropic's figures)

Claude Opus 5

Anthropic's July 2026 flagship at $5/$25 with a 1M window and an effort dial — near-frontier quality pitched on cost per task, not raw peak — and it is the newer of the two.

Computer use — surpasses Fable 5's best OSWorld 2.0 result at just over a third of the cost

Claude Opus 5

Claude Opus 5 lists computer use — surpasses Fable 5's best OSWorld 2.0 result at just over a third of the cost among its strengths; Gemini 3.6 Flash does not.

High-volume, cost-sensitive work — Google says it uses about 17% fewer output tokens than 3.5 Flash

Gemini 3.6 Flash

At $1.5/$7.5 per 1M tokens it undercuts Claude Opus 5 ($5/$25 per 1M tokens), and that gap compounds at volume.

Multimodal input across text, image and video at a 1M-token window

Gemini 3.6 Flash

Google's July 2026 workhorse Flash model at $1.50/$7.50 with a 1M window — tuned for cheap, high-volume multimodal work over benchmark peaks — and it runs cheaper at $1.5/$7.5 per 1M tokens.

Fast, cheap general assistance — the model behind much of Gemini's billion-plus Search reach

Gemini 3.6 Flash

Claude Opus 5 is comparatively weak here — behind Mythos 5 on cybersecurity exploitation and biology research, by Anthropic's own account

Lowest cost at scale

Gemini 3.6 Flash

At $1.5/$7.5 per 1M tokens, it is the cheaper of the two — the gap dominates the bill on high-volume workloads.

Which should you pick?

A cost-sensitive startup shipping high volume

Gemini 3.6 Flash

At $1.5/$7.5 per 1M tokens it undercuts Claude Opus 5, and on millions of tokens that margin decides the monthly bill.

Someone analysing very long documents or codebases

Gemini 3.6 Flash

Larger 1M window fits more in one prompt.

Anyone whose priority is frontier reasoning at lower cost per task — anthropic reports it more than doubling opus 4.8 on frontier-bench v0.1

Claude Opus 5

It is specifically built for that.

Anyone whose priority is high-volume, cost-sensitive work — google says it uses about 17% fewer output tokens than 3.5 flash

Gemini 3.6 Flash

That is its strongest area.

Claude Opus 5: where it fits

Anthropic's July 2026 flagship at $5/$25 with a 1M window and an effort dial — near-frontier quality pitched on cost per task, not raw peak. Released July 24, 2026 by Anthropic, it is built for frontier reasoning at lower cost per task — Anthropic reports it more than doubling Opus 4.8 on Frontier-Bench v0.1, agentic coding — within 0.5% of Fable 5's peak CursorBench 3.2 score at half the cost per task (Anthropic's figures), computer use — surpasses Fable 5's best OSWorld 2.0 result at just over a third of the cost, and a native effort setting (low, medium, high, xhigh, max) that trades token cost against capability on a single model.

Its trade-offs are real: behind Mythos 5 on cybersecurity exploitation and biology research, by Anthropic's own account, all launch benchmarks are Anthropic-reported and not yet independently reproduced, no published SWE-Bench Verified score, so head-to-head coding comparisons rely on Anthropic's own benchmark suite, and fast mode's throughput costs double the base price ($10/$50 per 1M). At $5 in / $25 out per million tokens, it sits in the premium price band.

Gemini 3.6 Flash: where it fits

Google's July 2026 workhorse Flash model at $1.50/$7.50 with a 1M window — tuned for cheap, high-volume multimodal work over benchmark peaks. Released July 21, 2026 by Google, it is built for high-volume, cost-sensitive work — Google says it uses about 17% fewer output tokens than 3.5 Flash, multimodal input across text, image and video at a 1M-token window, fast, cheap general assistance — the model behind much of Gemini's billion-plus Search reach, and strong price-to-capability for everyday tasks rather than frontier reasoning.

Its trade-offs: a Flash-tier model — not built to top reasoning or coding leaderboards against flagships, google reports SWE-Bench Pro rather than SWE-Bench Verified, so coding comparisons are not apples-to-apples, cheaper 3.5 Flash-Lite undercuts it when you do not need the extra capability, and google held its 3.5 Pro flagship back as not ready, so the Flash line is carrying the release. At $1.5 in / $7.5 out per million tokens, it sits in the mid price band.

The bottom line for this matchup

Claude Opus 5 and Gemini 3.6 Flash overlap enough that the right pick depends on your specific job. Gemini 3.6 Flash costs less per token; Gemini 3.6 Flash holds the larger context; and each leads in its own area — Claude Opus 5 for frontier reasoning at lower cost per task — anthropic reports it more than doubling opus 4.8 on frontier-bench v0.1, Gemini 3.6 Flash for high-volume, cost-sensitive work — google says it uses about 17% fewer output tokens than 3.5 flash. Rather than crowning one, run the same hard task through both once and let the results decide.

Want both Claude Opus 5 and Gemini 3.6 Flash without two subscriptions? LumiChats gives you these plus 40+ models under one ₹69/day pass (about $1/day) — draft with one, cross-check with the other.

See pricing

Frequently asked questions

Is Claude Opus 5 or Gemini 3.6 Flash better for coding?

Public SWE-Bench figures are not available for either model, so the honest test is your own repository — run an identical real bug through both. By design, Claude Opus 5 leans toward frontier reasoning at lower cost per task — anthropic reports it more than doubling opus 4.8 on frontier-bench v0.1 while Gemini 3.6 Flash leans toward high-volume, cost-sensitive work — google says it uses about 17% fewer output tokens than 3.5 flash, and that positioning usually predicts which feels better on your codebase.

Which is cheaper, Claude Opus 5 or Gemini 3.6 Flash?

Gemini 3.6 Flash is cheaper — $5/$25 per 1M tokens vs $1.5/$7.5 per 1M tokens, roughly 3.3× apart on input.

Which has the bigger context window?

Effectively neither — 1M vs 1M is a difference of a few percent. Remember advertised ≠ usable: recall typically degrades before the ceiling.

Can I use both Claude Opus 5 and Gemini 3.6 Flash together?

Yes — a multi-model platform like LumiChats gives you Claude Opus 5, Gemini 3.6 Flash and 40+ others under one ₹69/day pass (about $1/day), so you can draft with one and cross-check with the other instead of buying two subscriptions.

Which is newer, Claude Opus 5 or Gemini 3.6 Flash?

Claude Opus 5 — released July 24, 2026, about 3 days after Gemini 3.6 Flash.

Related comparisons

Specifications and benchmarks reflect publicly reported figures as of June 2026 and may change as providers release updates. Always verify on your own workload.