DeepSeek V4 Flash is $29.9 cheaper per 1M input tokens (99.7% lower; 300x difference).
API cost decision in 10 seconds
🔥DeepSeek V4 Flash vs GPT-5.5 Pro
Pick DeepSeek V4 Flash for lower cost; pick GPT-5.5 Pro only if the larger context window matters more.
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Data confirmed:
Prices normalized to USD per 1M tokens
Sample workload: 1M input + 500K output
Budget verdict
Pick DeepSeek V4 Flash for lower cost; pick GPT-5.5 Pro only if the larger context window matters more.
On the standard 1M input plus 500K output workload, DeepSeek V4 Flash is estimated at $0.2 vs $120 for GPT-5.5 Pro, saving $119.8 (99.8% lower).
Cost-first pickDeepSeek V4 Flash
Context-first pickGPT-5.5 Pro
Sample savings$119.899.8%
10x traffic gap$1198
GPT-5.5 Pro has more context, but DeepSeek V4 Flash saves $119.8 on the standard workload. At 10x that traffic, the same price gap is about $1198. Use the calculator below to replace the sample workload with your own token volume.
Cost sensitivity
Workload Sensitivity
DeepSeek V4 Flash stays cheaper across input-heavy, balanced, and output-heavy sample workloads.
| Workload shape | Token mix | Better pick | DeepSeek V4 Flash | GPT-5.5 Pro |
|---|---|---|---|---|
| Input-heavy / RAG | 5M input + 500K output | DeepSeek V4 Flash | $0.6 | $240 |
| Balanced workload | 1M input + 1M output | DeepSeek V4 Flash | $0.3 | $210 |
| Output-heavy chatbot | 1M input + 5M output | DeepSeek V4 Flash | $1.1 | $930 |
DeepSeek V4 Flash is $179.8 cheaper per 1M output tokens (99.9% lower; 900x difference).
GPT-5.5 Pro has 1.42K more context (1x larger).
DeepSeek V4 Flash is $119.8 cheaper on the standard workload (99.8% lower).
Estimate your workload cost
Your Workload Cost
This estimate uses normalized public API pricing per 1M tokens. It is a planning aid, not a billing quote. Verify provider pricing, limits, and terms before production use.
Quick Decision
DeepSeek V4 Flash has the lower input price; DeepSeek V4 Flash has the lower output price; GPT-5.5 Pro offers the larger context window. For the 1M input plus 500K output sample, DeepSeek V4 Flash is cheaper for the standard workload.
For a 1M input token plus 500K output token workload, the estimated API cost is $0.2 for DeepSeek V4 Flash and $120 for GPT-5.5 Pro.
Choose DeepSeek V4 Flash when you care most about lower input-token price, and lower output-token price.
Choose GPT-5.5 Pro when you care most about larger context window.
- On the standard 1M input plus 500K output workload, DeepSeek V4 Flash is estimated at $0.2 vs $120 for GPT-5.5 Pro, saving $119.8 (99.8% lower).
- DeepSeek V4 Flash is $119.8 cheaper on the standard workload (99.8% lower).
- DeepSeek V4 Flash is $29.9 cheaper per 1M input tokens (99.7% lower; 300x difference).
- DeepSeek V4 Flash is $179.8 cheaper per 1M output tokens (99.9% lower; 900x difference).
- GPT-5.5 Pro has 1.42K more context (1x larger).
| Feature | 🔥DeepSeek V4 Flash (DeepSeek) | GPT-5.5 Pro (OpenAI) |
|---|---|---|
| Input Price prompt tokens per 1M | $0.1 | $30 |
| Completion Price per 1M tokens | $0.2 | $180 |
| Sample Workload Cost 1M input + 500K output | $0.2 | $120 |
| Context Window | 1.05M | 1.05M |
| Release Date | ||
| Popularity | #1 |
Use-Case Decision Matrix
| Use case | Better pick | Why |
|---|---|---|
| Budget-constrained production | DeepSeek V4 Flash | On the standard 1M input plus 500K output workload, DeepSeek V4 Flash is estimated at $0.2 vs $120 for GPT-5.5 Pro, saving $119.8 (99.8% lower). |
| High-volume input processing | DeepSeek V4 Flash | Lower prompt-token price matters most when prompts, retrieved passages, or documents dominate the bill. |
| Long responses and chatbots | DeepSeek V4 Flash | Lower output-token price matters most when assistants generate many completion tokens. |
| RAG or long-document work | GPT-5.5 Pro | A larger context window leaves more room for retrieved passages, conversation history, or source files. |
Related Alternatives
- DeepSeek V4 Flash (free) can replace DeepSeek V4 Flash when lower sample workload cost matters most: $0.
- gpt-oss-120b (free) can replace GPT-5.5 Pro when lower sample workload cost matters most: $0.
- gpt-oss-20b (free) can replace GPT-5.5 Pro when lower sample workload cost matters most: $0.
- gpt-oss-20b can replace GPT-5.5 Pro when lower sample workload cost matters most: $0.1.
- Llama 4 Scout offers 10M context with $0.23 sample workload cost.
- Grok 4.20 Multi-Agent offers 2M context with $5 sample workload cost.
- Grok 4.20 offers 2M context with $2.5 sample workload cost.
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Open OpenAI modelsDeepSeek V4 Flash is an efficiency-optimized Mixture-of-Experts model from DeepSeek with 284B total parameters and 13B activated parameters, supporting a 1M-token context window. It is designed for fast inference and...
GPT-5.5 Pro is OpenAI’s high-capability model optimized for deep reasoning and accuracy on complex, high-stakes workloads. It features a 1M+ token context window (922K input, 128K output) with support for...