Last verified 2026-02-11 (left) · 2025-12-18 (right)

Claude Opus 4.5 (Legacy) vs Gemini 3 Flash — Pricing & Capability Comparison

Claude Opus 4.5 (Legacy) charges $5.00 per million input tokens and $25.00 per million output tokens. Gemini 3 Flash comes in at $0.50 / $3.00. Context windows span 200K vs 1M tokens respectively.

TL;DR — Quick Comparison

✓Gemini 3 Flash is cheaper overall: $3.50 per 1M tokens (in+out) vs $30.00 for Claude Opus 4.5 (Legacy) — saves $26.50 per 1M tokens
✓Input pricing: Claude Opus 4.5 (Legacy) $5.00/1M vs Gemini 3 Flash $0.50/1M
✓Output pricing: Claude Opus 4.5 (Legacy) $25.00/1M vs Gemini 3 Flash $3.00/1M
✓Context window: Gemini 3 Flash offers more (1M vs 200K)
✓Use our calculator below to estimate costs for your specific usage pattern

Input price (per 1M)

Claude Opus 4.5 (Legacy)

$5.00

Gemini 3 Flash

$0.50

Gemini 3 Flash leads here

Output price (per 1M)

Claude Opus 4.5 (Legacy)

$25.00

Gemini 3 Flash

$3.00

Gemini 3 Flash leads here

Context window

Claude Opus 4.5 (Legacy)

200,000 tokens

Gemini 3 Flash

1,000,000 tokens

Gemini 3 Flash leads here

Cached input

Claude Opus 4.5 (Legacy)

$0.500

Gemini 3 Flash

$0.050

Gemini 3 Flash leads here

Which one should you choose?

Skip the spreadsheet if you just need the practical takeaway. Use these rules when deciding between Claude Opus 4.5 (Legacy) and Gemini 3 Flash.

Choose Gemini 3 Flash if input tokens dominate your bill

Gemini 3 Flash has the lower input rate, which usually matters most for chat, RAG, classification, and long-prompt workflows where prompt volume stays much larger than generated output.

Choose Gemini 3 Flash if you generate long answers

Gemini 3 Flash is cheaper on output tokens, so it tends to win for report generation, coding assistance, reasoning traces, and any workflow where completions are long.

Choose Gemini 3 Flash if context size is the blocker

Gemini 3 Flash offers the larger published context window, which is more important than small pricing differences when you need to fit large files, long chats, or multi-document prompts into one request.

Cost comparison for 10K-token workloads

Side-by-side pricing for identical workloads (10,000 total tokens per request) across different distributions.

Scenario	Claude Opus 4.5 (Legacy)	Gemini 3 Flash	Claude Opus 4.5 (Legacy) cached	Gemini 3 Flash cached
Balanced conversation 50% input · 50% output	$0.150	$0.0175	$0.128	$0.0152
Input-heavy workflow 80% input · 20% output	$0.0900	$0.0100	$0.0540	$0.0064
Generation heavy 30% input · 70% output	$0.190	$0.0225	$0.177	$0.0212
Cached system prompt 90% cached input · 10% fresh output	$0.0700	$0.0075	$0.0295	$0.0034

Frequently asked questions

Which is cheaper: Claude Opus 4.5 (Legacy) or Gemini 3 Flash?

Gemini 3 Flash is cheaper for input tokens at $0.50 per 1M tokens compared to $5.00. For output, Gemini 3 Flash costs $3.00 per 1M tokens versus $25.00 for Claude Opus 4.5 (Legacy).

What is the cost per 1M tokens for Claude Opus 4.5 (Legacy)?

Claude Opus 4.5 (Legacy) pricing: $5.00 per 1M input tokens and $25.00 per 1M output tokens. Context window: 200,000 tokens.

What is the cost per 1M tokens for Gemini 3 Flash?

Gemini 3 Flash pricing: $0.50 per 1M input tokens and $3.00 per 1M output tokens. Context window: 1,000,000 tokens.

How much does it cost per 1K tokens?

Per 1K tokens: Claude Opus 4.5 (Legacy) costs $0.0050 input / $0.0250 output. Gemini 3 Flash costs $0.0005 input / $0.0030 output. This is useful for calculating small-scale usage costs.

Which model supports a larger context window?

Gemini 3 Flash offers 1,000,000 tokens (1M) versus 200K for Claude Opus 4.5 (Legacy).

What is the estimated monthly cost for typical usage?

For a typical workload of 10M input + 2M output tokens per month: Claude Opus 4.5 (Legacy) would cost approximately $100.00, while Gemini 3 Flash would cost $11.00. Gemini 3 Flash is more economical for this usage pattern.

Do these models support prompt caching?

Claude Opus 4.5 (Legacy) supports prompt caching at $0.500 per 1M cached tokens, reducing costs for repeated context by up to 90%. Gemini 3 Flash supports caching at $0.050 per 1M tokens, saving up to 90%.

Which model is best for my use case?

Choose Gemini 3 Flash for cost-sensitive applications with high input volume. Choose Gemini 3 Flash if you need 1M context for long documents or conversations. Consider prompt caching if you have repeated context. Use our token calculator to model your specific usage pattern.