GPT-OSS 20B vs Kimi K3
Benchmarks, API Token Pricing, Context Window & Speed Comparison
Related topics (4)
Compare GPT-OSS 20B by OpenAI against Kimi K3 by Moonshot AI across real-world coding, reasoning, token economics, and latency.
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GPT-OSS 20B
Open ReasoningAn open-weight GPT reasoning model for self-hosted agents and controllable deployments.
$0.10 / 1M
$0.50 / 1M
131.1K tokens
32.5%
Kimi K3
2.8T Open ReasonerMonumental 2.8-trillion parameter open-weights multimodal frontier model featuring 1M context window and toggleable max-effort thinking.
$0.00 / 1M
$0.00 / 1M
1.05M tokens
74.5%
Key Differences at a Glance
- Kimi K3 is 1.0x cheaper for API usage (input + output tokens combined).
- Kimi K3 has a larger context window (1M vs 131K tokens).
- GPT-OSS 20B is faster at 160 tok/s vs 58 tok/s.
- Kimi K3 leads on SWE-bench coding (74.5% vs 32.5%).
| Feature | GPT-OSS 20B | Kimi K3 |
|---|---|---|
Intelligence Index Composite reasoning & knowledge score (0-100) | 46 | 93 |
Provider | OpenAI | Moonshot AI |
Input Price Cost per million input tokens | $0.10 / 1M | $0.00 / 1M |
Output Price Cost per million output tokens | $0.50 / 1M | $0.00 / 1M |
Blended Price Weighted 7:2:1 cache:input:output per 1M | $0.08 / 1M | $0.00 / 1M |
Context Window Maximum input + output tokens | 131.1K tokens~197 A4 pages of text | 1.05M tokens~1,573 A4 pages of text |
Max Output Tokens Per single request | 33K | 131K |
Throughput Speed Tokens generated per second | 160 tok/s | 58 tok/s |
SWE-bench Verified Real-world software engineering | 32.5% | 74.5% |
GPQA Diamond Graduate-level reasoning | 55% | 79% |
Cached Input Price Prompt caching discount per 1M tokens | $0.01 / 1M | $0.00 / 1M |
Who Wins Where?
At-a-glance decision frameworkEmpirical Head-to-Head Benchmark Scores
Official evaluation metrics verified by independent third-party research labs.
Industry benchmark evaluating real-world GitHub issue resolution and multi-file debugging.
Challenging questions created by domain experts to test complex PhD-level reasoning.
Hardened reasoning and academic knowledge benchmark with reduced lucky-guess probability.
Crowdsourced human preference evaluation based on blind, head-to-head model battles.
Extremely difficult, closed-ended questions spanning the frontier of human expert knowledge.
Autonomous multi-step tasks executed inside a real command-line terminal environment.
Research-grade coding problems drawn from real scientific and numerical workloads.
Contamination-free competitive programming problems collected continuously over time.
American Invitational Mathematics Examination — multi-step Olympiad-level reasoning.
Accuracy when reasoning over very large inputs that fill the model context window.
Tokens emitted per second during active generation streaming.
Latency & Response Time
Time to first token (TTFT) and estimated end-to-end response time for a typical 500-token response.
Real-Time Interactive Token Cost Simulator
Adjust sliders to calculate projected monthly cloud API spending with prompt caching discounts.
GPT-OSS 20B · Strengths & Key Advantages
- Open weights — run it fully on your own hardware
- Small enough for a laptop or single consumer GPU
- Cheap on hosted providers and supports tool calling
- Runs comfortably on consumer hardware
Considerations & Trade-offs
- Clearly weaker than frontier models on hard reasoning
- Text-only — no vision or audio input
- Needs careful prompt tuning to reach its best output
Kimi K3 · Strengths & Key Advantages
- Largest open-weights foundation model in existence (2.8T parameters)
- 1480 LMSYS Chatbot Arena Elo rivaling proprietary closed frontier leaders
- Full 1M token context window paired with massive 131K max output tokens
Considerations & Trade-offs
- Extreme hardware prerequisites (distributed multi-node cluster deployment)
- Generates extensive reasoning traces that demand careful token budget management
Token Use & Task Economics
Estimated cost and token consumption to complete one representative agentic task.
| Metric | GPT-OSS 20B | Kimi K3 |
|---|---|---|
Cost per Task Estimated USD to finish one task | $0.09 | $2.00 |
Output Tokens / Task Tokens generated per task | 40K | 35K |
Reasoning Tokens / Task Thinking tokens burned per task | 18K | 18K |
Technical Specifications
Architecture, release timeline, capabilities, and modalities.
| Feature | GPT-OSS 20B | Kimi K3 |
|---|---|---|
| Official API Model ID (SDK) | gpt-oss-20b | kimi-k3 |
| API Protocol | OpenAI Responses API & Chat Completions v1 | OpenAI-Compatible REST / vLLM / SGLang / HuggingFace TGI |
| Release Date | 2025-08 | 2026-07 |
| Knowledge Cutoff | June 2024 | March 2026 |
| Architecture | Sparse MoE transformer with reasoning | Colossus-Scale Multimodal Sparse Mixture-of-Experts |
| Parameters | 21B (3.6B active MoE) | 2.8T total (MoE) |
| Enterprise Rate Limits (RPM / TPM) | Unlimited (Hardware-bound on self-hosted GPU) / 10,000 RPM Cloud · Unlimited local throughput / 10M+ TPM Managed Cloud | Unlimited (Hardware-bound on self-hosted GPU) / 10,000 RPM Cloud · Unlimited local throughput / 10M+ TPM Managed Cloud |
| Long-Context Tier (>128K/200K) | Flat rate ($0.1/1M in) across full 131K window | Free across full context window (only KV-cache VRAM scales) |
| Prompt Cache Policy & TTL | Automatic prefix caching at $0.01/1M (no extra cache-write fee) | Automatic prefix KV-caching in vLLM / SGLang (0 cost) |
| Computer Use / GUI Agent | API / CLI Tool-Use & DOM Agent ready (no raw pixel desktop click loop) | Supported (Screen coordinate grounding, browser & desktop GUI action loops) |
| MCP & Parallel Tool Calling | Native MCP Client/Server ready · Parallel function calling · 100% Strict JSON Schema | Native MCP Client/Server ready · Parallel function calling · 100% Strict JSON Schema |
| Web Search Grounding & Sandbox | Native Web Search tool + Hosted Code Interpreter & File Search RAG | Supported via external Tavily/Exa Search & E2B/Docker Sandbox tools |
| Official Fine-Tuning Support | Full Weights SFT, LoRA, QLoRA, DPO & GRPO RL (Unsloth / Axolotl / Llama-Factory) | Full Weights SFT, LoRA, QLoRA, DPO & GRPO RL (Unsloth / Axolotl / Llama-Factory) |
| Multimodal Token Billing | Text BPE (~4 chars/token) | Text BPE (~4 chars/token) · Vision (~258–765 tokens per image tile) |
| Quantization & Min GPU VRAM | BF16 / FP16, FP8 Dynamic, INT4 AWQ / GPTQ, GGUF (Q4_K_M / Q8_0) · 13 GB VRAM (4-bit Quantized) · 45 GB VRAM (Native BF16) | BF16 / FP16, FP8 Dynamic, INT4 AWQ / GPTQ, GGUF (Q4_K_M / Q8_0) · 1736 GB VRAM (4-bit Quantized) · 6020 GB VRAM (Native BF16) |
| Safety & Frontier Classification | OpenAI Preparedness Framework Audited & System Card Published | Open-Weights System Card + Customizable Guardrail Layer (Llama Guard / ShieldGemma) |
| Enterprise Compliance (ZDR/HIPAA/SOC2) | 100% Air-Gapped On-Premises / Private VPC · Full HIPAA, GDPR & SOC2 Control | 100% Air-Gapped On-Premises / Private VPC · Full HIPAA, GDPR & SOC2 Control |
| Input Modalities | text | text, vision |
| Output Modalities | text | text |
GPT-OSS 20B vs Kimi K3: Quick Answers
Which is more intelligent, GPT-OSS 20B or Kimi K3?
Kimi K3 is more intelligent. It scores 93 compared with 46 on the composite Intelligence Index.
Which model is faster?
GPT-OSS 20B is faster, generating 160 tokens per second compared with 58 tokens per second.
Which model is cheaper to run?
Kimi K3 is cheaper at $0.00 per 1M tokens blended, compared with $0.08 (7:2:1 cache:input:output ratio).
Which model has lower latency?
GPT-OSS 20B has lower latency, with a time to first token of 0.26s compared with 0.72s.
Which model has a larger context window?
Kimi K3 has a larger context window, supporting 1.05M tokens compared with 131.1K tokens.
Verdict
Choose GPT-OSS 20B for self-hosted agents, on-premise deployments and privacy-sensitive work, or choose Kimi K3 for national ai research facilities, sovereign enterprise clouds, and frontier stem reasoning.
Frequently asked questions
Which is cheaper: GPT-OSS 20B or Kimi K3?+
GPT-OSS 20B costs $0.1/1M input and $0.5/1M output tokens, while Kimi K3 costs $0/1M input and $0/1M output tokens.
Which model has a larger context window: GPT-OSS 20B or Kimi K3?+
GPT-OSS 20B supports 131K tokens whereas Kimi K3 supports 1.0M tokens.
Understand key metrics like context window, token pricing, reasoning mode, and SWE-bench scores in our comprehensive AI glossary.
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Benchmark scores, token prices, and rate limits evolve rapidly as AI labs release model updates. Always verify current specifications and pricing on the official provider documentation.
Sources: OpenAI & Moonshot AI Official Documentation