DeepSeek: DeepSeek V3.1 Terminus vs OpenAI: GPT-5 Nano
Head-to-head API pricing and cost comparison between DeepSeek’s DeepSeek: DeepSeek V3.1 Terminus and OpenAI’s OpenAI: GPT-5 Nano. Prices auto-refresh daily from OpenRouter.
OpenAI: GPT-5 Nano is 76% cheaper for input tokens; OpenAI: GPT-5 Nano also wins on output tokens.
Side-by-side comparison
| Spec | DeepSeek: DeepSeek V3.1 Terminus | OpenAI: GPT-5 Nano |
|---|---|---|
| Input price (per 1M) | $0.21 | $0.05 |
| Cached input (per 1M) | $0.13 | $0.01 |
| Output price (per 1M) | $0.79 | $0.40 |
| Batch input (per 1M) | — | $0.02 |
| Batch output (per 1M) | — | $0.20 |
| Reasoning price (per 1M) | — | — |
| Context window | 164K | 400K |
| Vision support | No | Yes |
| Caching support | Yes | Yes |
| Batch API | No | Yes |
| Reasoning capability | No | No |
Monthly cost at volume
Estimated monthly API spend at common production traffic levels (input/output tokens per request shown).
| Volume | DeepSeek: DeepSeek V3.1 Terminus | OpenAI: GPT-5 Nano | Savings |
|---|---|---|---|
1K req/day 500in / 200out tokens | $7.89 | $3.15 | $4.74 OpenAI: GPT-5 Nano wins |
10K req/day 1500in / 500out tokens | $213.00 | $82.50 | $130.50 OpenAI: GPT-5 Nano wins |
100K req/day 3000in / 800out tokens | $3,786 | $1,410 | $2,376 OpenAI: GPT-5 Nano wins |
1M req/day 8000in / 2000out tokens | $97,800 | $36,000 | $61,800 OpenAI: GPT-5 Nano wins |
Adjust input/output token counts, request volume, batch & cached pricing.
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Frequently asked questions
Which is cheaper, DeepSeek: DeepSeek V3.1 Terminus or OpenAI: GPT-5 Nano?
For input tokens, OpenAI: GPT-5 Nano is roughly 76% cheaper at $0.05/1M vs $0.21/1M. For output tokens, OpenAI: GPT-5 Nano wins at $0.40/1M. Real-world cost depends on your input/output ratio — use the calculator to model your actual workload.
What’s the context window difference?
DeepSeek: DeepSeek V3.1 Terminus has a context window of 164K tokens. OpenAI: GPT-5 Nano offers 400K tokens. Larger context windows are valuable for long documents, RAG pipelines, and multi-turn conversations — but they come with higher input-token bills if you fill them every request.
Should I use DeepSeek: DeepSeek V3.1 Terminus or OpenAI: GPT-5 Nano?
Choose DeepSeek: DeepSeek V3.1 Terminus if you’re already on the DeepSeek stack, want broad ecosystem support, or prefer its feature set. Choose OpenAI: GPT-5 Nano for OpenAI’s ecosystem, native vision input, or its cheaper input tokens. Run a small benchmark on your own prompts before committing — price is only one axis.
How are these prices kept current?
Prices are pulled directly from OpenRouter’s public models API once every 24 hours via a Convex cron job, then normalized to per-1M-token figures. Last refresh: Apr 21, 2026.