Claude Sonnet 5 vs Kimi K3
Anthropic's Claude Sonnet 5 and Moonshot AI's Kimi K3 both target production language workloads, but they price and behave differently. Here is the side-by-side.
Pricing checked against provider documentation on . How we verify
The short answer
Claude Sonnet 5 is the cheaper option — roughly 1.5x less on a blended workload, and it suits fast claude-quality reasoning at scale. Kimi K3 justifies its premium when you need natively multimodal long-horizon agents.
Anthropic • Claude 5
$2.00 / $10.00
/ 1M tokens (input / output)
The workhorse Claude tier: a full million tokens of context and adaptive thinking at $2/$10, which undercuts the previous Sonnet 4.6 generation by a third on input while raising the context ceiling fivefold. The default pick for latency-sensitive products that still want Claude's writing and tool-use behaviour.
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 50% more expensive than Claude Sonnet 5 on input tokens.
Output price
Kimi K3 is 50% more expensive than Claude Sonnet 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 Sonnet 5 | Kimi K3 | Difference |
|---|---|---|---|
| Light — 1M in / 200K out | $4 | $6 | $2 |
| Moderate — 10M in / 2M out | $40 | $60 | $20 |
| Heavy — 100M in / 20M out | $400 | $600 | $200 |
Specification comparison
| Attribute | Claude Sonnet 5 | Kimi K3 |
|---|---|---|
| Input (/ 1M tokens) | $2.00 | $3.00 |
| Output (/ 1M tokens) | $10.00 | $15.00 |
| Cached input | $0.20 | $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 | 2026-01 | 2026-02 |
| Relative latency | low | high |
| Open weights | No | Kimi K3 License (commercial terms above $20M revenue) |
| API model ID | claude-sonnet-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 Sonnet 5 if…
- Production chat and copilots
- Long-document analysis
- Tool-heavy agents needing fast turns
- Code review and PR automation
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 Sonnet 5 or Kimi K3 cheaper?
Claude Sonnet 5 is cheaper. On a blended 3:1 input-to-output workload it costs about 1.5x less than Kimi K3.
Which has the larger context window, Claude Sonnet 5 or Kimi K3?
Kimi K3 has the larger window at 1.05M tokens versus 1M.
Should I use Claude Sonnet 5 or Kimi K3?
Pick Claude Sonnet 5 for fast claude-quality reasoning at scale. Pick Kimi K3 for natively multimodal long-horizon agents. If cost dominates the decision, Claude Sonnet 5 wins; if you need the capability ceiling, benchmark both on your own evals before committing.