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GPT-5.6 Sol vs GPT-5.4
A straight cost comparison of GPT-5.6 Sol (OpenAI) and GPT-5.4 (OpenAI), per 1,000,000 tokens, verified October 2026.
Rate-by-rate comparison
| Metric | GPT-5.6 Sol | GPT-5.4 | Winner |
|---|---|---|---|
| Input / 1M | $4 | $2.50 | GPT-5.4 |
| Cached input / 1M | $0.40 | $0.25 | GPT-5.4 |
| Cache write / 1M | $5 | — | GPT-5.4 |
| Output / 1M | $20 | $15 | GPT-5.4 |
| Context window | 1,050,000 | 1,050,000 | Tie |
| Batch API | Yes | Yes | Tie |
| Long-context tier | > 272,000 | > 272,000 | — |
For per-token metrics, the lower number wins. For context window and batch support, the higher or broader option wins. A dash means the provider does not publish that rate: a missing cache-write fee means writes are not billed per token, while a missing cached-input rate means cache hits bill at the full input rate.
Blended cost: 1M input + 250K output
| Model | Blended cost | Difference |
|---|---|---|
| GPT-5.6 Sol | $9 | +$2.75 |
| GPT-5.4 | $6.25 | Cheaper |
Three workloads, two bills
| Workload | GPT-5.6 Sol | GPT-5.4 | Winner |
|---|---|---|---|
| Support chat 1,000 requests · 4K input / 600 output | $28 | $19 | GPT-5.4 |
| RAG with caching 1,000 requests · 50K input (45K cached) / 1K output | $58.21 | $38.85 | GPT-5.4 |
| Nightly batch job 10,000 requests · 10K input / 2K output | $400 | $275 | GPT-5.4 |
Which one should you pick?
GPT-5.6 Sol wins on none of the three workloads above, while GPT-5.4 wins on support chat, cached RAG, nightly batch job.
Beyond price, the two differ on input rate ($4 vs $2.50); output rate ($20 vs $15); cached-input rate ($0.40 vs $0.25); cache-write rate ($5 vs —).
Batch mode is available on GPT-5.6 Sol and GPT-5.4, which halves the nightly job. Both publish cached-input discounts, so a stable system prompt is worth caching on either.
FAQ
Is GPT-5.6 Sol cheaper than GPT-5.4?
On a blended 1M-input-plus-250K-output workload, GPT-5.4 is cheaper by 31% ($6.25 vs $9). The gap changes for cache-heavy prompts and for batch jobs, as the workload table shows.
Which handles longer prompts, GPT-5.6 Sol or GPT-5.4?
Both models share the same 1,050,000-token context window. Watch the long-context threshold on GPT-5.6 Sol and GPT-5.4: rates rise once input passes it.
Do both models support prompt caching?
GPT-5.6 Sol bills cached reads at $0.40 per 1M; GPT-5.4 at $0.25.