GPT-5.6 Sol vs DeepSeek V4 Pro
DeepSeek V4 Pro is the cheaper of the two across every workload shape tested below. Headline rates are $5 in / $30 out for GPT-5.6 Sol versus $1.32 in / $3.96 out for DeepSeek V4 Pro, per million tokens.
Real monthly cost, three workloads
| Workload | GPT-5.6 Sol | DeepSeek V4 Pro | Cheaper |
|---|---|---|---|
| Support chatbot 1.5k in / 400 out · 100k req/mo · 30% cached | $1,748 | $298.98 | DeepSeek V4 Pro (5.8× cheaper) |
| RAG / doc Q&A 12k in / 700 out · 50k req/mo · 60% cached | $2,430 | $471.24 | DeepSeek V4 Pro (5.2× cheaper) |
| Coding agent 25k in / 2.5k out · 20k req/mo · 80% cached | $2,200 | $347.60 | DeepSeek V4 Pro (6.3× cheaper) |
Costs include prompt caching at the stated hit rate and per-model tokenizer correction. Adjust for your own traffic →
Specifications side by side
| GPT-5.6 Sol | DeepSeek V4 Pro | |
|---|---|---|
| Provider | OpenAI | DeepSeek |
| Input / M tokens | $5 | $1.32 |
| Output / M tokens | $30 | $3.96 |
| Cached input | $0.5 | $0.044 |
| Context window | 1050K | 1000K |
| Batch discount | −50% | — |
| Tokenizer factor | ×1 | ×1 |
| Min prefix to cache | — | — |
| Announced retirement | — | — |
Which should you pick?
On cost alone, DeepSeek V4 Pro wins every workload shape above.
Full detail: GPT-5.6 Sol · DeepSeek V4 Pro
All figures verified 2026-08-18 against official provider documentation. Fields a provider does not publish are shown as “—” rather than estimated.