Claude Opus 5 vs Kimi K3
Anthropic's Claude Opus 5 and Moonshot AI's Kimi K3 both target production language workloads, but they price and behave differently. Here is the side-by-side.
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The short answer
Kimi K3 is the cheaper option — roughly 1.7x less on a blended workload, and it suits natively multimodal long-horizon agents. Claude Opus 5 justifies its premium when you need most teams' best claude starting point.
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.
Moonshot AI • Kimi K
$3.00 / $15.00
/ 1M tokens (input / output)
At 2.8T total parameters with 104B active, Kimi K3 is the largest open-weight model in general circulation and the only one here that ingests video natively. Reasoning is always on with configurable effort. The licence is the catch: it is not a standard open licence, and organisations above $20M in revenue need a separate commercial agreement.
Input price
Kimi K3 is 40% cheaper than Claude Opus 5 on input tokens.
Output price
Kimi K3 is 40% 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 | Kimi K3 | Difference |
|---|---|---|---|
| Light — 1M in / 200K out | $10 | $6 | $4 |
| Moderate — 10M in / 2M out | $100 | $60 | $40 |
| Heavy — 100M in / 20M out | $1,000 | $600 | $400 |
Specification comparison
| Attribute | Claude Opus 5 | Kimi K3 |
|---|---|---|
| Input (/ 1M tokens) | $5.00 | $3.00 |
| Output (/ 1M tokens) | $25.00 | $15.00 |
| Cached input | $0.50 | $0.30 |
| Context window | 1,000,000 tokens | 1,048,576 tokens |
| Max output | 128,000 tokens | 131,072 tokens |
| Native reasoning | Yes | Yes |
| Knowledge cutoff | 2026-05 | 2026-02 |
| Relative latency | medium | high |
| Open weights | No | Kimi K3 License (commercial terms above $20M revenue) |
| API model ID | claude-opus-5 | kimi-k3 |
| Status | stable | stable |
Kimi K3: The custom licence requires a separate commercial agreement once the licensee and its affiliates exceed $20M revenue over any consecutive 12 months.
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 Kimi K3 if…
- Multimodal agent workflows
- Video and image understanding at length
- Ambitious long-horizon automation
- Research requiring open weights at scale
Frequently asked
Is Claude Opus 5 or Kimi K3 cheaper?
Kimi K3 is cheaper. On a blended 3:1 input-to-output workload it costs about 1.7x less than Claude Opus 5.
Which has the larger context window, Claude Opus 5 or Kimi K3?
Kimi K3 has the larger window at 1.05M tokens versus 1M.
Should I use Claude Opus 5 or Kimi K3?
Pick Claude Opus 5 for most teams' best claude starting point. Pick Kimi K3 for natively multimodal long-horizon agents. If cost dominates the decision, Kimi K3 wins; if you need the capability ceiling, benchmark both on your own evals before committing.