Capability · Comparison
GPT-5 Nano vs GPT-5 Mini
Both sit under GPT-5 proper as cost-optimised tiers, but they target different workloads. Nano is the 'touch every row in the database' tier — classification, extraction, simple answers at massive scale. Mini is the general-purpose workhorse most GPT-5 pipelines actually run on.
Side-by-side
| Criterion | GPT-5 Mini | GPT-5 Nano |
|---|---|---|
| Tier within GPT-5 family | Mid | Smallest |
| Latency on short prompts | Fast | Fastest |
| Reasoning capability | Strong — close to GPT-4o class | Deliberately limited, GPT-4o-mini class |
| Tool-call reliability | Good | Basic — plan tool use upstream |
| Context window | 400,000 tokens | 400,000 tokens |
| Pricing ($/M input) | $2 | $0.40 |
| Pricing ($/M output) | $8 | $1.60 |
| Best fit | General chat, RAG, agents | Classification, extraction, router models |
Verdict
If you're building an actual product on GPT-5, Mini is almost always the right default — it's closer to flagship behaviour than to Nano, and its cost is still modest. Nano wins only when volume is huge and every prompt is trivially simple (routing, classification, tagging, sentiment). A common pattern is Nano as a first-stage router and Mini (or GPT-5 full) as the follow-on worker.
When to choose each
Choose GPT-5 Mini if…
- You're building a chat assistant, RAG stack, or agent.
- You need tool-use, JSON outputs, or multi-turn reasoning.
- You want a clear quality upgrade path to GPT-5 flagship.
- Prompt length is moderate and cost isn't the single constraint.
Choose GPT-5 Nano if…
- You're doing classification, extraction, routing, or tagging at scale.
- You can prompt away most reasoning requirements.
- You want the cheapest GPT-5-family call possible.
- You're stacking Nano as a cheap first pass in front of Mini / GPT-5.
Frequently asked questions
How small is GPT-5 Nano compared to GPT-5?
OpenAI doesn't publish parameters, but Nano behaves as a much smaller, faster, and cheaper model. Expect roughly GPT-4o-mini-class reasoning with GPT-5 API behaviour.
Can GPT-5 Nano do tool calling?
Yes, but with noticeably less reliability than Mini. For agent-style loops, prefer Mini; use Nano for single-shot classification plus routing.
How should students split workloads between them?
A typical pattern: Nano tags and routes incoming requests; Mini handles normal reasoning; GPT-5 flagship only handles escalated hard cases. That tier-down pattern keeps costs sane at demo scale.
Sources
- OpenAI — GPT-5 family pricing — accessed 2026-04-20
- OpenAI — Models — accessed 2026-04-20