GPT-5.6 Sol API Pricing
GPT-5.6 Sol is OpenAI's highest-accuracy GPT-5.6 tier for hard reasoning, coding and senior-agent workloads, and it has now had a cut of its own: $4/M input, $20/M output and $0.40/M cached input, against $5 / $30 / $0.50 before. Input-side rates fell to 0.8x and output to two thirds, taking the effective agentic rate from $3.81 to $2.73/M. OpenAI labels the new card promotional and guarantees it at least through November 21, 2026 without publishing what comes after. Sol sat out the July 30 cut that took Luna down 80% and Terra 20% - this one is its own, and it is the only GPT-5 row that moved: Terra, Luna, 5.5, 5.4 and both -pro tiers read unchanged on the same page.
Run the numbers.
Live calculator pre-loaded with current GPT-5.6 Sol standard short-context rates. Tweak spend, output mix, or cache hit rate; share the URL to share the calculation.
Real-world presets.
Repo-wide architecture migration
Multi-step diligence brief
Reading 150-page contracts
Executive workflow turn
Paste text. See tokens. See cost.
Counted with the o200k_base BPE encoding — the same tokenizer the API uses — entirely in your browser. The encoder loads on your first keystroke (~1 MB, one time); your text never leaves this page.
| Model | Input /M | Output /M | Effective blended | Context | Best for |
|---|---|---|---|---|---|
| GPT-5.6 Sol Current | $4.00 cache $0.40 | $20.00 | $2.73 agentic 92/8 | 1.05M | Highest-accuracy GPT-5.6 preview |
| GPT-5.6 Terra | $2.00 cache $0.20 | $12.00 | $1.52 same blend | 1.05M | Balanced GPT-5.6 preview agents |
| GPT-5.6 Luna | $0.20 cache $0.02 | $1.20 | $0.152 same blend | 1.05M | Cheapest GPT-5.6 preview routing |
| GPT-5.5 | $5.00 cache $0.50 | $30.00 | $3.61 same blend | 1M | Current broadly available OpenAI flagship |
| GPT-5.4 | $2.50 cache $0.25 | $15.00 | $1.80 same blend | 1.05M | Broadly available balanced OpenAI tier |
| GPT-5.4 mini | $0.75 cache $0.075 | $4.50 | $0.541 same blend | 400K | Lower-cost OpenAI subagents |
| Claude Opus 4.8 | $5.00 cache $0.50 | $25.00 | $3.41 same blend | 1M | Anthropic Opus frontier alternative |
| Gemini 3.5 Flash | $1.50 cache $0.15 | $9.00 | $1.08 same blend | 1M | Google multimodal context alternative |
Compare siblings
Frequently asked.
Practical GPT-5.6 Sol pricing questions, with OpenAI's published rates separated from workload assumptions.
Q · 01 How much does GPT-5.6 Sol cost? +
Q · 02 Is GPT-5.6 Sol generally available? +
Q · 03 What is the context window? +
1.05M-token context window and 128K max output for GPT-5.6 Sol, with a stated knowledge cutoff of February 16, 2026.Q · 04 How much cheaper are Batch and Flex? +
$2/M input, $0.20/M cached input, $2.50/M cache writes and $10/M output. Fast mode - the tier renamed from Priority on July 30, 2026 - is double standard: $8/M input, $0.80/M cached input, $10/M cache writes and $40/M output.Q · 05 When does long-context pricing apply? +
272K input tokens, GPT-5.6 Sol uses the long-context tier: $8/M input, $0.80/M cached input, $10/M cache writes and $30/M output — double the standard input rate and 1.5x the standard output rate, the same multipliers as before the cut. The calculator on this page uses the standard short-context tier.Q · 06 Which GPT-5.6 tier should I choose? +
$2.73/M, Terra near $1.52/M, and Luna near $0.15/M. The August cut narrowed the family: Luna is 17.9x cheaper than Sol, down from 25x, and Sol is only 1.8x Terra rather than 2.5x - which is exactly the sort of change that makes an old routing rule wrong.Q · 07 Did Sol get cheaper in the 2026 price cuts? +
$4 / $0.40 / $5 / $20 - which brings the blended agentic rate to $2.73/M and narrows the gap to Luna to 17.9x. Unlike July, this one comes labelled promotional, guaranteed at least through November 21, 2026, with no published rate for what follows.