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GPT-4.1 vs GPT-4o: What Changed, What It Costs, and How to Migrate

OpenAI deprecated GPT-4o in April 2025 and replaced it with the GPT-4.1 family. If you're still calling gpt-4o in production, here's why you should switch: GPT-4.1 is 20% cheaper, has an 8× larger context window (1M vs 128K tokens), and supports up to 32K output tokens. The migration takes about 5 minutes.

Pricing Comparison

GPT-4.1 undercuts GPT-4o on every metric that matters — price per token and context capacity:

Context Window: 1M vs 128K

The biggest upgrade isn't price — it's context. GPT-4.1's 1M token context window is 8× larger than GPT-4o's 128K. In practical terms:

• Entire codebases — Upload a 50K-line repo and ask questions about it in one request
• Long documents — Process 800+ page PDFs without chunking
• Full conversation history — No more summarizing or truncating old messages
• Multi-file analysis — Compare 20+ files side by side in a single prompt

With GPT-4o's 128K limit, you'd hit the ceiling on many real-world tasks. GPT-4.1 eliminates that constraint entirely.

Real Cost Breakdowns

Let's see what this means for actual workloads:

Chatbot (100K daily messages)

Code Review (10K daily reviews)

Document Analysis (1K daily queries)

How to Migrate

The migration is minimal. Here's what to change:

1. Update your model parameter

Change model: "gpt-4o" to model: "gpt-4.1" in your API calls. That's it for basic usage.

2. Check your max_tokens

GPT-4.1 supports up to 32K output tokens (vs GPT-4o's 16K). If you were hitting output limits, you can increase max_tokens now.

3. Test with a few requests

GPT-4.1 may produce slightly different outputs for the same prompts. Run a small test batch before switching production traffic. Most developers report identical or better quality.

4. Update your budget model too

If you're using GPT-4o mini, consider switching to GPT-4.1 mini ($0.40/$1.60) for the 8× context boost, or GPT-4.1 nano ($0.10/$0.40) for the cheapest option with 1M context.

When to Stick with Alternatives

GPT-4.1 isn't always the right choice. Consider these alternatives:

• Claude Sonnet 5 ($2/$10 intro) — better for long-form writing and analysis, same price tier
• DeepSeek V4 Pro ($0.27/$1.10) — 7× cheaper for code tasks if you don't need OpenAI's ecosystem
• Gemini 2.5 Pro ($1.25/$10) — 2M context window, best for extremely long documents
• Mistral Small 4 ($0.15/$0.60) — ultra-budget with 128K context

Related Guides

• Claude Sonnet 5 vs GPT-5.5 — flagship comparison
• Top 10 Cheapest AI APIs in 2026 — budget options ranked
• How to Switch LLM Providers — step-by-step migration guide
• Full model comparison tool — all 58 models side by side