AI model comparison
Mercury 2 vs GPT-5 Nano
Pricing, context window, benchmarks, and features compared side by side. Or skip the guesswork and send one prompt to both.
Inception
Mercury 2
Mercury 2 is an extremely fast reasoning LLM, and the first reasoning diffusion LLM (dLLM).
- Input / 1M
- $0.25
- Output / 1M
- $0.75
- Context
- 128K
OpenAI
GPT-5 Nano
GPT-5-Nano is the smallest and fastest variant in the GPT-5 system, optimized for developer tools, rapid interactions, and ultra-low latency environments.
- Input / 1M
- $0.05
- Output / 1M
- $0.40
- Context
- 400K
At a glance
Quick verdict
How the two models stack up on the things people ask about most.
Lower price
GPT-5 Nano
2.9x cheaper for a typical chat
Higher intelligence score
Mercury 2
13.8 vs 13 on Artificial Analysis
Larger context window
GPT-5 Nano
400K vs 128K tokens
Newer release
Mercury 2
Released March 4, 2026
Benchmarks
Benchmark scores
Independent scores from Artificial Analysis. Higher is better.
Intelligence index
Mercury 213.8GPT-5 Nano13Coding index
Mercury 231.1GPT-5 NanoNot availableAgentic index
Mercury 21.6GPT-5 NanoNot availablePricing
Mercury 2 vs GPT-5 Nano API pricing
Per-token API rates. Cheaper option highlighted.
| Metric | Mercury 2 | GPT-5 Nano |
|---|---|---|
| Input tokensPer 1M tokens | $0.25 | $0.05 |
| Output tokensPer 1M tokens | $0.75 | $0.40 |
| Cached input (read)Per 1M tokens | $0.03 | $0.01 |
| Cache writePer 1M tokens | Not available | Not available |
| Web searchPer request | Not available | $0.01 |
What it costs in practice
Estimated cost per 1,000 requests at standard rates. Coding and long-document figures also show the cost when the input is already cached.
Chat message
2K in, 500 out
Mercury 2$0.88GPT-5 Nano$0.30Coding task
30K in, 4K out
Mercury 2$10.50$3.75 cachedGPT-5 Nano$3.10$1.75 cachedLong document summary
150K in, 2K out
Mercury 2$39$5.25 cachedGPT-5 Nano$8.30$1.55 cachedSpecs
Context window and capabilities
How much each model can read, how much it can write, and what it accepts as input.
| Metric | Mercury 2 | GPT-5 Nano |
|---|---|---|
| Context window | 128K tokens | 400K tokens |
| Max output | 50K tokens | 128K tokens |
| Input types | Text | File, Image, Text |
| Output types | Text | Text |
| Reasoning effort levels | High, Medium, Low, None | High, Medium, Low, Minimal |
| Default reasoning effort | Medium | Medium |
| Release date | March 4, 2026 | August 7, 2025 |
Features
Supported features
API features available for each model.
| Metric | Mercury 2 | GPT-5 Nano |
|---|---|---|
| Tool calling | Supported | Supported |
| Structured outputs | Supported | Supported |
| JSON mode | Supported | Supported |
| Reasoning | Supported | Supported |
| Temperature | Supported | Not supported |
| Stop sequences | Supported | Not supported |
| Deterministic seed | Not supported | Supported |
| Verbosity control | Not supported | Supported |
Keep exploring
More on these models
Other head-to-heads, the full model page, and the alternatives list for each model.
GPT-5 NanoView full model details- GPT-5 Nano vs Gemini 2.5 Flash Lite
- GPT-5 Nano vs GPT-6 Luna Pro
- GPT-5 Nano vs gpt-oss-120b
- GPT-5 Nano vs Gemma 4 31B
- GPT-5 Nano vs Gemma 4 26B A4B
- GPT-5 Nano vs gpt-oss-20b
- GPT-5 Nano vs GPT-4o-mini
- GPT-5 Nano vs Qwen3 235B A22B Instruct 2507
- GPT-5 Nano vs DeepSeek V3.1
- GPT-5 Nano vs Mercury 2.5
- GPT-5 Nano vs Qwen3.5-9B
- GPT-5 Nano vs Nemotron 3.5 Lightning
- GPT-5 Nano vs GPT-4.1 Nano
- GPT-5 Nano vs Granite 4.2 8B
- GPT-5 Nano vs GLM 4.7 Flash
- GPT-5 Nano vs DeepSeek V3.2 Exp
- GPT-5 Nano vs Nemotron 3 Super
- GPT-5 Nano vs Mistral Small 4
- GPT-5 Nano vs Step 3.5 Flash
Our take
GPT-5 Nano is 2.9x cheaper for a typical chat. Mercury 2 scores higher on the Artificial Analysis Intelligence Index (13.8 vs 13). GPT-5 Nano has the larger context window (400K vs 128K tokens). The right pick depends on your workload, so the quickest way to settle it is to send the same prompt to both and compare.
FAQ
Frequently asked questions
Is Mercury 2 or GPT-5 Nano cheaper?
GPT-5 Nano is cheaper for a typical chat (2K input tokens and 500 output tokens). GPT-5 Nano costs $0.05 per 1M input tokens and $0.40 per 1M output tokens, while Mercury 2 costs $0.25 per 1M input tokens and $0.75 per 1M output tokens.
Which has a bigger context window, Mercury 2 or GPT-5 Nano?
GPT-5 Nano supports up to 400K tokens of context, compared with 128K for Mercury 2.
Is Mercury 2 smarter than GPT-5 Nano?
On the Artificial Analysis Intelligence Index, Mercury 2 scores 13.8 and GPT-5 Nano scores 13, putting Mercury 2 ahead. Benchmarks don't capture everything, so the best test is running your own prompts through both.
Can I use Mercury 2 and GPT-5 Nano at the same time?
Yes. Shortcut Chat sends one prompt to multiple models at once, so you can see Mercury 2 and GPT-5 Nano answer side by side and keep the better response.
Why choose? Ask both.
Send one prompt to Mercury 2 and GPT-5 Nano at the same time. Compare the answers side by side and keep the best one.