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gpt-oss-20b vs GPT-4o-mini

Detailed technical comparison between gpt-oss-20b (OpenAI) and GPT-4o-mini (OpenAI). Review live API token pricing, context window capabilities, time-to-first-token latency, and verified benchmark scores side-by-side.

⚡ Executive Summary & Verdict

Comparison Snapshot

gpt-oss-20b: 0 WinsvsGPT-4o-mini: 6 Wins
Context Leader

gpt-oss-20b

131,072 tokens
Agentic Tool-Calling

Tie

Equal Capability
Lowest Latency (TTFT)

Tie

Equal Speed
Input Price Leader

gpt-oss-20b

$0.03 / MTok
OpenAIactive

gpt-oss-20b

gpt-oss-20b is an open-weight 21B parameter model released by OpenAI under the Apache 2.0 license. It uses a Mixture-of-Experts (MoE) architecture with 3.6B active parameters per forward pass, optimized for...

View gpt-oss-20b Full Specs →
OpenAIactive

GPT-4o-mini

GPT-4o mini is OpenAI's newest model after [GPT-4 Omni](/models/openai/gpt-4o), supporting both text and image inputs with text outputs. As their most advanced small model, it is many multiples more affordable...

View GPT-4o-mini Full Specs →

Technical Specifications

🏆 = Superior Spec
Specificationgpt-oss-20bGPT-4o-mini
ProviderOpenAIOpenAI
Context Window131,072 tokens🏆128,000 tokens
Agent SuitabilityN/A82/100
Time to First Token (TTFT)N/A150 ms
Deployment Modelmanaged apimanaged api
Production Stabilitystablestable
API AvailableYesYes
Released Date2025-08-052024-07-18

API Pricing Comparison

Input Price per Million Tokens

gpt-oss-20b

$0.03

GPT-4o-mini

$0.15

Output Price per Million Tokens

gpt-oss-20b

$0.13

GPT-4o-mini

$0.60

💡 Cost Ratio: gpt-oss-20b is 5.0x cheaper per input token than GPT-4o-mini.

Want to test both models live?

Run side-by-side prompt benchmarks in our dynamic multi-model Sandbox. Compare execution speeds, latency metrics, and compute actual costs in real-time.

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Benchmark Performance Metrics

Standardized Scores (0–100%)

Scores show verified raw accuracy percentages across standardized AI evaluation suites. Higher bars indicate superior performance in that domain.

MMLUGeneral knowledge & multi-task understanding
79.8%vs82.0%+2.2% GPT-4o-mini
gpt-oss-20b
GPT-4o-mini 🏆
HumanEvalPython coding & logic synthesis
78.0%vs84.0%+6.0% GPT-4o-mini
gpt-oss-20b
GPT-4o-mini 🏆
MATHComplex mathematical problem solving
55.2%vs70.2%+15.0% GPT-4o-mini
gpt-oss-20b
GPT-4o-mini 🏆
GPQAGraduate-level expert reasoning
40.6%vs45.0%+4.4% GPT-4o-mini
gpt-oss-20b
GPT-4o-mini 🏆
HellaSwagCommonsense reasoning and inference
82.8%vs84.7%+1.9% GPT-4o-mini
gpt-oss-20b
GPT-4o-mini 🏆
MT-BenchMulti-turn conversation flow quality
8.5%vs8.6%+0.1% GPT-4o-mini
gpt-oss-20b
GPT-4o-mini 🏆

gpt-oss-20b Quirks & Gotchas

No developer gotchas reported.

GPT-4o-mini Quirks & Gotchas

  • ▸Ultra-low latency — best TTFT in the OpenAI lineup
  • ▸Tool calling limited to single-step — not suitable for complex agentic pipelines

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