DeepSeek V3 vs GPT-5.5 Instant
Pricing, benchmarks, and use case comparison
Quick take
- •DeepSeek V3 is meaningfully stronger at cost efficiency (92 vs 70 on our capability index).
- •GPT-5.5 Instant is meaningfully stronger at multimodal (82 vs 10).
- •DeepSeek V3 is open-weights (free to self-host); GPT-5.5 Instant is paid API only.
- •GPT-5.5 Instant has a 1050000 context window vs 128K tokens - better for whole-repo or long-document work.
Specs comparison
| DeepSeek V3 | GPT-5.5 Instant | |
|---|---|---|
| Provider | DeepSeek | OpenAI |
| Type | Open source | Closed source |
| Context window | 128K tokens | ✓1050000 |
| Input / 1M tokens | ✓Free (self-host) | 5.00 |
| Output / 1M tokens | Free (self-host) | 30.00 |
| Release date | 2024-12 | 2026-05 |
Benchmarks
| Benchmark | DeepSeek V3 | GPT-5.5 Instant |
|---|---|---|
| Pre-training scale | ~15T tokens | - |
| AIME 2025 | - | 81.2 |
| Terminal-Bench 2.0 | - | 82.7 |
| FrontierMath Tier 1–3 | - | 51.7 |
Scores sourced from official provider release posts and independent benchmark aggregators.
Which should you choose?
Choose DeepSeek V3 if...
- →You want a proven, stable open model with broad ecosystem support
- →You need to self-host or fine-tune without licensing friction
- →Cost is critical and you don't need V4's 1M context or top scores
- →You want reproducible open-weight behavior pinned to a known version
Choose GPT-5.5 Instant if...
- →Interactive chat and everyday assistant tasks where responsiveness matters most
- →High-volume, latency-sensitive workloads that do not need deep reasoning
- →General questions, drafting, and summarization at speed