DeepSeek V4 Flash vs GPT-5.6 Sol
Pricing, benchmarks, and use case comparison
Quick take
- •DeepSeek V4 Flash is meaningfully stronger at cost efficiency (95 vs 55 on our capability index).
- •GPT-5.6 Sol is meaningfully stronger at multimodal (88 vs 10).
- •DeepSeek V4 Flash is open-weights (free to self-host); GPT-5.6 Sol is paid API only.
Specs comparison
| DeepSeek V4 Flash | GPT-5.6 Sol | |
|---|---|---|
| Provider | DeepSeek | OpenAI |
| Type | Open source | Closed source |
| Context window | ✓1M tokens | Not announced |
| Input / 1M tokens | ✓Free (self-host) | $5.00 |
| Output / 1M tokens | Free (self-host) | $30.00 |
| Release date | 2026-04 | 2026-06 |
Benchmarks
| Benchmark | DeepSeek V4 Flash | GPT-5.6 Sol |
|---|---|---|
| Reasoning (vs V4 Pro) | Closely approaches V4 Pro | - |
| Terminal-Bench 2.1 | - | 88.8% |
| Terminal-Bench 2.1 (Ultra) | - | 91.9% |
| ExploitBench | - | competitive with Mythos Preview |
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 Sol if...
- →You are an approved preview partner needing the most capable model for agentic software engineering
- →Complex multi-step tasks that benefit from subagent orchestration (Ultra) or maximum reasoning depth (max)
- →Frontier scientific research, professional knowledge work, or security-sensitive workloads