Claude Opus 5 vs Gemini 3.1 Flash-Lite
Anthropic's Claude Opus 5 and Google's Gemini 3.1 Flash-Lite both target production language workloads, but they price and behave differently. Here is the side-by-side.
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The short answer
Gemini 3.1 Flash-Lite is the cheaper option — roughly 17.8x less on a blended workload, and it suits ultra-cheap high-volume tasks. Claude Opus 5 justifies its premium when you need most teams' best claude starting point. Only Claude Opus 5 does native reasoning, which matters for multi-step tasks but adds billable thinking tokens.
Anthropic • Claude 5
$5.00 / $25.00
/ 1M tokens (input / output)
A step change over Opus 4.8 on deep reasoning and long-horizon agentic work, at half Fable 5's price and with the freshest knowledge cutoff in the Claude line. Anthropic's own guidance is that most teams should benchmark Opus 5 before paying for Fable 5.
Google • Gemini 3.1
$0.25 / $1.50
/ 1M tokens (input / output)
Google's efficiency tier and a long-term stable target, priced for workloads measured in millions of calls rather than thousands. It gives up the deeper reasoning of 3.5 Flash, so it suits mechanical tasks — classification, extraction, moderation — where a million tokens of context still helps but chain-of-thought does not.
Input price
Gemini 3.1 Flash-Lite is 95% cheaper than Claude Opus 5 on input tokens.
Output price
Gemini 3.1 Flash-Lite is 94% cheaper than Claude Opus 5 on output tokens — usually the side that dominates the bill.
Monthly cost at three workload sizes
Standard (non-batch, non-cached) rates. Reasoning models will exceed these figures because thinking tokens bill as output.
| Workload | Claude Opus 5 | Gemini 3.1 Flash-Lite | Difference |
|---|---|---|---|
| Light — 1M in / 200K out | $10 | $1 | $9 |
| Moderate — 10M in / 2M out | $100 | $6 | $95 |
| Heavy — 100M in / 20M out | $1,000 | $55 | $945 |
Specification comparison
| Attribute | Claude Opus 5 | Gemini 3.1 Flash-Lite |
|---|---|---|
| Input (/ 1M tokens) | $5.00 | $0.25 |
| Output (/ 1M tokens) | $25.00 | $1.50 |
| Cached input | $0.50 | — |
| Context window | 1,000,000 tokens | 1,048,576 tokens |
| Max output | 128,000 tokens | 65,536 tokens |
| Native reasoning | Yes | No |
| Knowledge cutoff | 2026-05 | 2025-01 |
| Relative latency | medium | low |
| Open weights | No | No |
| API model ID | claude-opus-5 | gemini-3.1-flash-lite |
| Status | stable | stable |
Choose Claude Opus 5 if…
- Agentic engineering with a cost ceiling
- Deep research and analysis
- Test-time compute scaling
- Production assistants needing recent knowledge
Choose Gemini 3.1 Flash-Lite if…
- Content moderation at volume
- Classification and routing
- Lightweight summarization
- Cheap long-context retrieval
Frequently asked
Is Claude Opus 5 or Gemini 3.1 Flash-Lite cheaper?
Gemini 3.1 Flash-Lite is cheaper. On a blended 3:1 input-to-output workload it costs about 17.8x less than Claude Opus 5.
Which has the larger context window, Claude Opus 5 or Gemini 3.1 Flash-Lite?
Gemini 3.1 Flash-Lite has the larger window at 1.05M tokens versus 1M.
Should I use Claude Opus 5 or Gemini 3.1 Flash-Lite?
Pick Claude Opus 5 for most teams' best claude starting point. Pick Gemini 3.1 Flash-Lite for ultra-cheap high-volume tasks. If cost dominates the decision, Gemini 3.1 Flash-Lite wins; if you need the capability ceiling, benchmark both on your own evals before committing.