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Claude Haiku 4.5 vs gpt-oss-20b

How do these models stack up? Below is an expert side-by-side comparison of specifications, context window capacity, live pricing per million tokens, and standardized benchmark scores for Claude Haiku 4.5 and gpt-oss-20b.

Anthropic

Claude Haiku 4.5

Claude Haiku 4.5 is Anthropic’s fastest and most efficient model, delivering near-frontier intelligence at a fraction of the cost and latency of larger Claude models. Matching Claude Sonnet 4’s performance...

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OpenAI

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...

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Technical Specifications

SpecificationClaude Haiku 4.5gpt-oss-20b
ProviderAnthropicOpenAI
Context Window200,000 tokens131,072 tokens
Agent Suitability87/100N/A
Time to First Token (TTFT)180 msN/A
Deployment Modelmanaged apimanaged api
Production Stabilitystablestable
API AvailableYesYes
Released Date2025-10-152025-08-05

API Pricing Comparison

Input Price per Million Tokens

Claude Haiku 4.5

$1.00

gpt-oss-20b

$0.03

Output Price per Million Tokens

Claude Haiku 4.5

$5.00

gpt-oss-20b

$0.14

Want to test both models live?

Run side-by-side prompt prompts in our dynamic Sandbox. Check execution speeds, latency metrics, and compute actual costs in real-time.

Benchmark Performance Metrics

Scores show the raw performance percentages verified across key evaluation suites. Higher bars indicate superior accuracy and capability in that domain.

MMLUGeneral knowledge & multi-task understanding
8480.0%vsN/A
Claude Haiku 4.5
gpt-oss-20b
HumanEvalPython coding & logic synthesis
8600.0%vsN/A
Claude Haiku 4.5
gpt-oss-20b
MATHComplex mathematical problem solving
7500.0%vsN/A
Claude Haiku 4.5
gpt-oss-20b
GPQAGraduate-level expert reasoning
5500.0%vsN/A
Claude Haiku 4.5
gpt-oss-20b
HellaSwagCommonsense reasoning and inference
9350.0%vsN/A
Claude Haiku 4.5
gpt-oss-20b
MT-BenchMulti-turn conversation flow quality
890.0%vsN/A
Claude Haiku 4.5
gpt-oss-20b

Claude Haiku 4.5 Quirks & Gotchas

  • Fastest TTFT in the Claude lineup — ideal for real-time chat
  • Tool calling limited compared to Sonnet — best for simple classification and routing

gpt-oss-20b Quirks & Gotchas

No developer gotchas reported.