Processing or generating 500,000 words (approximately 640,000 tokens) with o3-pro (Frontier Reasoning) ranges from $1.28 (cached input) to $51.20 (full generation).
Quick answer
For 500,000 words, o3-pro (Frontier Reasoning) processes approximately 640,000 tokens. That costs $12.80 as uncached input, $1.28 with the modeled cache discount, or $51.20 when generated as output.
Method & trust
The estimate converts the selected English word count with the model tokenizer family, then applies the published input/output price per million tokens. Real prompts vary with code, formatting, language, and system instructions.
You send 500,000 words as prompt context, documentation, or background knowledge.
o3-pro (Frontier Reasoning) drafts a complete 500,000 words article, chapter, or code module.
400,000 words input prompt + 100,000 words output reply.
| Model | Provider | Input Cost (500,000 words) | Cached Input Cost | Output Cost (500,000 words) | Context Limit |
|---|---|---|---|---|---|
| o3-pro (Frontier Reasoning) (Current) | openai | $12.80 | $1.28 | $51.20 | 1,000,000 |
| GPT-5.6 Sol | openai | $3.20 | $0.32 | $19.20 | 1,050,000 |
| GPT-5.6 Cyber | openai | $8.00 | $0.80 | $48.00 | 1,050,000 |
| GPT-5.5 Standard | openai | $3.20 | $0.32 | $19.20 | 512,000 |
| GPT-5.5 Pro | openai | $19.20 | $1.92 | $115.20 | 512,000 |
| o3 (Reasoning Frontier) | openai | $6.40 | $0.64 | $25.60 | 1,050,000 |
For o3-pro (Frontier Reasoning) (o200k_base tokenizer), 500,000 words is approximately 640,000 tokens (an average ratio of 1.28 tokens per word in English). Code, technical vocabulary, and non-English scripts will have higher token densities.
Sending 500,000 words as input costs $12.80 (or $1.28 with prompt caching). Generating 500,000 words as output costs $51.20. Output tokens are more expensive because autoregressive token generation requires significantly more computation per token.
Yes! If your input text is part of a repeated context, prompt caching saves 50% to 90% (costing $1.28). For non-urgent asynchronous batch processing, 24-hour batch queues provide a flat 50% discount across all tokens (costing $6.40 for input, $25.60 for output).
At an average human reading speed of 250 words per minute, 500,000 words takes approximately 2000 minutes to read. In contrast, o3-pro (Frontier Reasoning) can process or generate this text in seconds.