DeepSeek V4 Flash vs GPT-5.5 — Side-by-side pricing
Side-by-side API pricing and tokenizer details for DeepSeek V4 Flash (DeepSeek) and GPT-5.5 (OpenAI).
Side-by-side pricing
| Feature | DeepSeek V4 Flash | GPT-5.5 |
|---|---|---|
| Provider | DeepSeek | OpenAI |
| Input (per 1M tokens) | $0.140 | $5.00 |
| Output (per 1M tokens) | $0.280 | $30.00 |
| Long-context pricing | Flat rate at any prompt size | Over 272K tokens: $10.00 in / $45.00 out |
| Context caching | Yes — 98% off cached tokens | Yes — 90% off cached tokens |
| Batch API discount | Not available | 50% off |
| Context window | 1M tokens | 1.1M tokens |
| Tokenizer | SentencePiece (Llama) | o200k_base (tiktoken) |
Real-world cost example
1,000 API requests per month, each with 500 input tokens and 200 output tokens (500K input + 200K output total).
DeepSeek V4 Flash
$0.1260
Input: $0.0700 +Output: $0.0560
GPT-5.5
$8.5000
Input: $2.5000 +Output: $6.0000
DeepSeek V4 Flash is 99% cheaper for this workload — saving $8.3740 per month at this volume.
Frequently asked questions
Yes, DeepSeek V4 Flash is cheaper for the typical workload above. At $0.140/1M input and $0.280/1M output tokens, it costs $0.1260 versus $8.5000 for GPT-5.5 — a 99% difference. Note that GPT-5.5 switches to long-context pricing above 272K prompt tokens, so for very long prompts this gap does not scale linearly.
DeepSeek V4 Flash supports a 1M token context window. GPT-5.5 supports a 1.1M token context window. A larger context window lets you include more text — documents, conversation history, or code — in a single API call.
DeepSeek V4 Flash supports context caching (98% off repeated tokens). It does not offer a batch API discount. GPT-5.5 supports context caching (90% off repeated tokens). It offers a 50% Batch API discount.
No, they use different tokenizers. DeepSeek V4 Flash uses the SentencePiece (Llama), while GPT-5.5 uses o200k_base (tiktoken). Different tokenizers split text differently, so the same prompt will produce different token counts on each model — the effective cost difference may be larger or smaller than the per-token price difference alone suggests.
DeepSeek V4 Flash (DeepSeek): $0.14 input / $0.28 output per 1M tokens. GPT-5.5 (OpenAI): $5 input / $30 output per 1M tokens. Rates shown before caching or batch discounts.
For an 80% output / 20% input workload — typical for code generation or long-form writing — DeepSeek V4 Flash costs $0.2520 per 1M total tokens and GPT-5.5 costs $25.0000. DeepSeek V4 Flash is 99% cheaper for this pattern. For your exact ratio, paste a real prompt into the calculator above.
DeepSeek V4 Flash has a 1M-token context window — approximately 750K words or ~3K pages of standard text. GPT-5.5 has a 1.1M-token context window — approximately 788K words or ~3K pages. (Estimates assume ~0.75 words per token.)
Calculate costs for your actual prompt
Paste your prompt into the calculator and get exact token counts using each model's real tokenizer — all in your browser.
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