CtrlAltDebrief

GPT-4o vs GPT-5.1

API pricing, context window and capabilities for GPT-4o and GPT-5.1, side by side. Prices are the cheapest serving route per 1M tokens, verified against LiteLLM and OpenRouter.

Verdict

computed from the published numbers

GPT-5.1 wins on price, on intelligence and on context window. Benchmark data is unavailable for one or both models.

Price
GPT-5.1
Coding
Not called
Intelligence
GPT-5.1
Context window
GPT-5.1

Key takeaways

who wins on what, from the published numbers

GPT-4o wins

  • More serving providers (6 vs 4)
  • Supports audio

GPT-5.1 wins

  • Cheaper input ($2.50 vs $1.25 /1M)
  • Larger context window (131K vs 410K)
  • Higher max output (16K vs 128K)
  • Has reasoning mode
  • Has web search
Cheaper overall
GPT-5.1
$1.25 + $10.00 /1M
Larger context
GPT-5.1
410K
More providers
GPT-4o
6 providers

Pricing & specs

cheapest serving route · per 1M tokens
GPT-4oGPT-5.1
Input $/1M$2.50 $1.25 best
Output $/1M$10.00 $10.00
Context window131K 410K best
Max output16K 128K best
Serving providers6 best4
Released2024-05-13 2025-11-13

Benchmarks

Artificial Analysis indices, side by side
GPT-4oGPT-5.1
Intelligence11.2 36.9 best
CodingNot available 49.4
GPQA Diamond54% 87% best
Output speed99 t/s best90 t/s
Latency (TTFT)5.19s best37.50s

Cost calculator

choose a serving route for each side
Input tokens / month
Output tokens / month
GPT-4o
via Azure
$23
GPT-5.1
via Databricks
$16

Capabilities

feature support, side by side
FeatureGPT-4oGPT-5.1
Vision✓✓
Tool use✓✓
Reasoning—✓
Audio✓—
Prompt caching✓✓
Structured output✓✓
Web search—✓

Related comparisons

Frequently asked questions

Which is cheaper, GPT-4o or GPT-5.1?
GPT-5.1 is cheaper for input ($2.50 vs $1.25 per 1M tokens).
What is the context window difference between GPT-4o and GPT-5.1?
GPT-4o has a 131K-token context window and GPT-5.1 has 410K tokens, so GPT-5.1 can take a larger prompt.
How do GPT-4o and GPT-5.1 compare on benchmarks?
On the tracked Artificial Analysis indices, GPT-5.1 leads on intelligence.
Pricing verified against LiteLLM + OpenRouter + provider pages · refreshed daily

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