Which is cheaper, Kimi K3 and GPT-5.5?

Kimi K3 has the lowest input price. Per 1M input tokens: Kimi K3 from $2.70 and GPT-5.5 from $5.00.

Which has the larger context window, Kimi K3 and GPT-5.5?

GPT-5.5 has the largest context window: Kimi K3 1,048,576 tokens and GPT-5.5 1,050,000 tokens.

Which is better for coding, Kimi K3 and GPT-5.5?

Kimi K3 scores highest on the Artificial Analysis Coding Index: Kimi K3 76.2 and GPT-5.5 74.9.

Which is faster, Kimi K3 and GPT-5.5?

Kimi K3 has the highest median throughput on FastRouter: Kimi K3 <1 t/s and GPT-5.5 <1 t/s.

Can I switch between Kimi K3 and GPT-5.5 without changing my code?

Yes. All of them are served through FastRouter's OpenAI-compatible API, so switching is a change of the model parameter (moonshotai/kimi-k3, openai/gpt-5.5).

Kimi K3 vs GPT-5.5

Side-by-side pricing per provider, context window, benchmark scores and speed, all on one OpenAI-compatible API.

Kimi K3 MoonshotAImoonshotai/kimi-k3

GPT-5.5 OpenAIopenai/gpt-5.5

Creator

MoonshotAI

OpenAI

Released

Jul 16, 2026

Apr 24, 2026

Context window

1.05M

Max output

1.05M

128K

Input / 1MLowest provider price

$2.70$2.70–$3.00 across 4

$5.00$5.00–$5.50 across 2

Output / 1MLowest provider price

$13.50$13.50–$15.00 across 4

$30.00$30.00–$33.00 across 2

Providers

IntelligenceArtificial Analysis index

43.6

38.4

CodingArtificial Analysis index

76.2

74.9

LatencyMedian time to first token

7.4s

6.1s

ThroughputMedian tokens per second

<1 t/s

Accepts

Text, Image

Files, Image, Text

Produces

Text

Tool calling

Yes

Structured output

Yes

Reasoning

Yes

Kimi K3 vs GPT-5.5: summary

Kimi K3 and GPT-5.5 are both available through FastRouter's OpenAI-compatible API, so switching between them is a change of model id, not a new integration.

Kimi K3, from MoonshotAI, has a 1,048,576-token context window, costs from $2.70/1M input and $13.50/1M output tokens across 4 providers and scores 43.6 on the Artificial Analysis Intelligence Index.

GPT-5.5, from OpenAI, has a 1,050,000-token context window, costs from $5.00/1M input and $30.00/1M output tokens across 2 providers and scores 38.4 on the Artificial Analysis Intelligence Index.

Kimi K3 is the cheapest on input, 1.9× cheaper than the next model, GPT-5.5 has the largest context window, Kimi K3 scores highest for intelligence, Kimi K3 leads on coding and Kimi K3 has the highest throughput.

Switch with one line

client = OpenAI(base_url="https://api.fastrouter.ai/api/v1", api_key="<FASTROUTER_API_KEY>") client.chat.completions.create(model="moonshotai/kimi-k3", messages=[...]) # or client.chat.completions.create(model="openai/gpt-5.5", messages=[...])

Full API docs

Frequently asked questions

More comparisons

Benchmark scores sourced from ArtificialAnalysis