DeepSeek V4 Flash vs GPT-5.6
Pricing, benchmarks, and use case comparison
Quick take
- •DeepSeek V4 Flash is meaningfully stronger at cost efficiency (95 vs 70 on our capability index).
- •GPT-5.6 is meaningfully stronger at multimodal (87 vs 10).
- •DeepSeek V4 Flash is open-weights (free to self-host); GPT-5.6 is paid API only.
Specs comparison
| DeepSeek V4 Flash | GPT-5.6 | |
|---|---|---|
| Provider | DeepSeek | OpenAI |
| Type | Open source | Closed source |
| Context window | ✓1M tokens | Not announced |
| Input / 1M tokens | ✓Free (self-host) | 5 |
| Output / 1M tokens | Free (self-host) | 30 |
| Release date | 2026-04 | 2026-06 |
Benchmarks
| Benchmark | DeepSeek V4 Flash | GPT-5.6 |
|---|---|---|
| Reasoning (vs V4 Pro) | Closely approaches V4 Pro | - |
| Terminal-Bench 2.1 (Sol) | - | 88.8% |
| Terminal-Bench 2.1 (Terra) | - | 82.5% |
| Terminal-Bench 2.1 (Luna) | - | 84.3% |
| Terminal-Bench 2.1 | - | 88.8 |
| ExploitBench | - | Competitive with Anthropic Mythos Preview |
| ExploitGym | - | Significant improvements |
| GeneBench v1 | - | Not announced |
Scores sourced from official provider release posts and independent benchmark aggregators.
Which should you choose?
Choose DeepSeek V4 Flash if...
- →You want most of V4 Pro's capability at a lower price and higher throughput
- →You need long context but on a tighter compute or cost budget
- →You are serving high request volumes where per-token cost dominates
- →You want an open model small enough to self-host on modest multi-GPU setups
Choose GPT-5.6 if...
- →You want to standardize on one model generation but route requests across cost/quality tiers
- →You are an approved preview partner exploring the newest OpenAI capabilities
- →Workloads spanning agentic coding, knowledge work, and research where tier flexibility helps