Model comparison · Updated May 2026
DeepSeek R1 vs GPT-5.5 Pro: Price, Context, Benchmarks (2026)
A direct, dated comparison of DeepSeek R1 (DeepSeek) and GPT-5.5 Pro (OpenAI). Every number below is sourced from official provider docs and public benchmarks. If you need to make this decision today, the verdict is at the top.
30-second verdict
- Cheaper: DeepSeek R1 (input $0.55 vs $30.00 per 1M tokens).
- Longer context: GPT-5.5 Pro at 1.1M vs 128K.
- Stronger on SWE-bench Verified: GPT-5.5 Pro (~70% vs ~52%).
- Higher LMArena: GPT-5.5 Pro (1465 vs 1418).
- Open weights: DeepSeek R1 can be self-hosted.
Specs side-by-side
| Spec | DeepSeek R1 | GPT-5.5 Pro |
|---|---|---|
| Vendor | DeepSeek | OpenAI |
| Input price (per 1M tokens) | $0.55 | $30.00 |
| Output price | $2.19 | $180.00 |
| Context window | 128K | 1.1M |
| Release date | 2025-01-20 | 2026-04-23 |
| SWE-bench Verified | ~52% | ~70% |
| HumanEval | ~93% | ~97% |
| LMArena (approx) | 1418 | 1465 |
| Open weights | Yes | No |
| Capabilities | reasoning, code, cheap | reasoning, code, vision |
Pricing from official DeepSeek and OpenAI docs. Benchmark numbers from SWE-bench Verified, HumanEval, and LMArena public leaderboards as of May 2026.
DeepSeek R1 — strengths and weaknesses
Strengths. Best price-to-quality, open weights, strong math + code, self-hostable.
Weaknesses. Weaker tool calling, smaller context, China-hosted official API.
Best for. Cost-sensitive production, batch jobs, self-hosted privacy use.
GPT-5.5 Pro — strengths and weaknesses
Strengths. Top-tier reasoning, asks better clarifying questions, deepest analysis.
Weaknesses. 6× the price of GPT-5.5 standard, slower.
Best for. High-stakes one-off problems, system design, math research.
Which one should you pick?
Pick DeepSeek R1 if: cost-sensitive production, batch jobs, self-hosted privacy use.
Pick GPT-5.5 Pro if: high-stakes one-off problems, system design, math research.
Use both if: you're building an agent or content pipeline. Route the high-stakes / hard-reasoning calls to whichever scores higher on the axis you care about, and the bulk / cheap calls to the other. Most production AI products run a 2-3 model router rather than betting on one.
Try them side-by-side
The Check.AI comparison tool lets you put both models in one table with all the numbers, switch capability filters, and share the resulting URL with your team.