GPT 5.1 vs GPT 4.1 (2025-04-14)

GPT 5.1 vs GPT 4.1 (2025-04-14): GPT 4.1 (2025-04-14) is cheaper by 43% on average. GPT 5.1 from Azure OpenAI (272,000-token context, reasoning, tool calls) vs. GPT 4.1 (2025-04-14) from Azure OpenAI (1,047,576-token context, tool calls). Use Agent Command Center to A/B both in shadow mode and pick the winner per workload.

Side-by-side cost

Live workload comparison

Same workload run through both models. The cheaper one is highlighted.

3,000
01,047,576
400
0128,000
5,000
01,000,000
GPT 5.1Cheaper
Azure OpenAI
$1,179/mo
Input $1.25/M · Output $10.00/M
Azure OpenAI
$1,540/mo
Input $2.20/M · Output $8.80/M
At this workload, GPT 5.1 is 23% cheaper than GPT 4.1 (2025-04-14) — a savings of $361/month ($4,328/year).
Crossover: GPT 5.1 is cheaper when output/input ≤ 0.79 (input-heavy workloads — RAG, retrieval). GPT 4.1 (2025-04-14) wins above (long-form generation).
Current workload ratio: 0.13 (400/3000)
Production recipe — Agent Command Center
strategy: cost-optimized
primary:
  model: gpt-5-1
  provider: azure-openai
fallback:
  model: us-gpt-4-1-2025-04-14
  provider: azure-openai
shadow: { sample_rate: 0.05 }   # mirror 5% of traffic to compare quality live
GPT 5.1 GPT 4.1 (2025-04-14)
Input price $1.25/M $2.20/M
Output price $10.00/M $8.80/M
Context window 272,000 1,047,576
Max output 128,000 32,768
Function calling
Vision
Audio input
Reasoning
Prompt caching
Structured output
Pricing verified May 12, 2026 May 12, 2026
Cheaper option
~43% cheaper than GPT 5.1
Larger context
1,047,576 tokens
More capabilities
5 of 6 capability flags advertised

Benchmark comparison

Side-by-side public benchmark scores. Greener bar = winner.

Chatbot Arena ELOgeneral
GPT 5.1
1,455
GPT 4.1 (2025-04-14)
AIME 2025math
GPT 5.1
94.0%
GPT 4.1 (2025-04-14)
GPQA Diamondreasoning
GPT 5.1
88.1%
GPT 4.1 (2025-04-14)
MMMUmultimodal
GPT 5.1
85.4%
GPT 4.1 (2025-04-14)
τ-bench (retail)agent
GPT 5.1
77.9%
GPT 4.1 (2025-04-14)
SWE-bench Verifiedagent
GPT 5.1
76.3%
GPT 4.1 (2025-04-14)
τ-bench (airline)agent
GPT 5.1
67.0%
GPT 4.1 (2025-04-14)
FrontierMathmath
GPT 5.1
26.7%
GPT 4.1 (2025-04-14)