GPT-5.6 Sol vs Kimi K3
OpenAI's GPT-5.6 Sol 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
Kimi K3 is the cheaper option — roughly 1.3x less on a blended workload, and it suits natively multimodal long-horizon agents. GPT-5.6 Sol justifies its premium when you need frontier coding and long-horizon agents.
OpenAI • GPT-5.6
$4.00 / $20.00
/ 1M tokens (input / output)
OpenAI's flagship tier and the current state of the art on agentic coding benchmarks. Reasoning effort is tunable from none through max, and an `ultra` setting coordinates parallel subagents across workstreams. Sol reaches near-Fable-5 intelligence while spending markedly fewer output tokens, which is why its cost per finished task lands well below its sticker price.
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 25% cheaper than GPT-5.6 Sol on input tokens.
Output price
Kimi K3 is 25% cheaper than GPT-5.6 Sol 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 | GPT-5.6 Sol | Kimi K3 | Difference |
|---|---|---|---|
| Light — 1M in / 200K out | $8 | $6 | $2 |
| Moderate — 10M in / 2M out | $80 | $60 | $20 |
| Heavy — 100M in / 20M out | $800 | $600 | $200 |
Specification comparison
| Attribute | GPT-5.6 Sol | Kimi K3 |
|---|---|---|
| Input (/ 1M tokens) | $4.00 | $3.00 |
| Output (/ 1M tokens) | $20.00 | $15.00 |
| Cached input | $0.40 | $0.30 |
| Context window | 1,048,576 tokens | 1,048,576 tokens |
| Max output | 128,000 tokens | 131,072 tokens |
| Native reasoning | Yes | Yes |
| Knowledge cutoff | 2026-02 | 2026-02 |
| Relative latency | high | high |
| Open weights | No | Kimi K3 License (commercial terms above $20M revenue) |
| API model ID | gpt-5.6-sol | kimi-k3 |
| Status | stable | stable |
GPT-5.6 Sol: Promotional pricing (down from $5/$30) held at least through 2026-11-21. Prompts above 272K input tokens bill at higher rates; 'fast' processing is 2x.
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 GPT-5.6 Sol if…
- Long-running autonomous coding agents
- Large-scale refactors and migrations
- Agentic browsing and computer use
- Scientific and financial analysis
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 GPT-5.6 Sol or Kimi K3 cheaper?
Kimi K3 is cheaper. On a blended 3:1 input-to-output workload it costs about 1.3x less than GPT-5.6 Sol.
Which has the larger context window, GPT-5.6 Sol or Kimi K3?
Both accept up to 1.05M tokens, so context is not a differentiator here.
Should I use GPT-5.6 Sol or Kimi K3?
Pick GPT-5.6 Sol for frontier coding and long-horizon agents. 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.