What is ERNIE 5.1?
ERNIE 5.1 is Baidu's flagship language model, officially released on 9 May 2026 after a preview topped the Chinese entries on LMArena's text leaderboard. Rather than training it from scratch, Baidu extracted it from ERNIE 5.0: Baidu says it has about a third of ERNIE 5.0's total parameters and half its active ones, and cost about 6% of the pre-training budget of comparable models. Baidu has not published parameter counts or weights.
It powers Baidu's ERNIE chat assistant and is sold through Baidu's Qianfan cloud platform, where the mainland catalogue lists it as a text-generation model with a 128K context and up to 65,536 output tokens. Although ERNIE 5.0 was built to handle images, audio and video, the 5.1 API is listed as text only.
Qianfan prices it in yuan: ¥0.004 per thousand input tokens and ¥0.018 per thousand output tokens for prompts up to 32K, about ¥4 and ¥18 per million, rising to ¥0.006 and ¥0.022 for longer prompts. Baidu publishes no dollar price, and as of late summer its international catalogue still listed only ERNIE 5.0.
How much does ERNIE 5.1 cost?
| Plan | Price | What you get |
|---|---|---|
| Prompts up to 32K | ¥0.004 in / ¥0.018 out per 1,000 tokens | Qianfan, mainland China |
| Prompts 32K to 128K | ¥0.006 in / ¥0.022 out per 1,000 tokens | |
| ERNIE 5.0 (international Qianfan) | $1.40 in / $5.60 out per 1M tokens | ERNIE 5.1 not yet in the international catalogue |
Qianfan (mainland China): ¥0.004 input / ¥0.018 output per 1,000 tokens up to 32K, ¥0.006 / ¥0.022 from 32K to 128K. No official dollar price; the international catalogue lists ERNIE 5.0 at $1.40 / $5.60 per 1M tokens. Free in the ERNIE assistant.
Is ERNIE 5.1 worth it?
ERNIE 5.1 is Baidu's answer to the cost race rather than a new frontier. Its headline claim is efficiency: distilled from ERNIE 5.0, it cost Baidu about 6% of a comparable model's pre-training budget. Its best independent result is search. On LMArena's Search Arena it scored 1,223 in May, fourth worldwide behind two Claude Opus versions and GPT-5.5 Search and first among Chinese models, though newer entries have since pushed it down.
Baidu's own claims are strongest in maths and agent tasks: 99.6 on the AIME26 competition with tools, second only to Gemini 3.1 Pro, and results above DeepSeek-V4-Pro on the τ³-bench and spreadsheet tests, for which the blog gives no figures. Independent reviewers have been less kind about coding and broad knowledge, and none of Baidu's numbers can be checked against open weights, because there are none.
The practical obstacles are access and terms. The API is listed as text only with a 128K context, smaller than the 1M windows of Kimi, MiMo and Qwen's flagships. It is priced in yuan on the mainland platform, missing from the international catalogue, and sign-up can require a Chinese phone number or business licence. Baidu's public pages also do not say whether Qianfan inputs are used for training.
For a team serving Chinese users through Baidu's ecosystem, it is a capable and cheap model. For everyone else, the open Chinese models do as much with fewer hurdles.
Where it earns its place
A Chinese consumer app adding an AI assistant
Answer questions with up-to-date, search-grounded responses
ERNIE 5.1's Search Arena result is its strongest independent score, and it runs inside Baidu's search and cloud ecosystem. On Qianfan, 100,000 answers of 2K input and 500 output tokens cost about ¥1,700.
An education company building maths tutoring for Chinese students
Solve and explain competition-level problems
Baidu reports 99.6 on AIME26 with tool use. Test it against your own problem set first, since the figure is Baidu's and the weights cannot be checked.
A multinational with a China subsidiary
Use a domestic model that meets mainland rules
Run it through the mainland Qianfan platform, where it is listed with a 128K context. Get a written data processing agreement covering training and retention first.
Before you commit
- Setup
- Chat with it free in Baidu's ERNIE assistant, try it in the AI Studio playground, or call ernie-5.1 through Qianfan's OpenAI-compatible API on the mainland platform. Default limits are 60 requests and 150,000 tokens a minute.
- Integrations
- Baidu Qianfan API (OpenAI-compatible), ERNIE assistant, Baidu AI Studio, and creative agent platforms that Baidu says are adding it.
- Data and privacy
- Closed weights. Baidu's international cloud privacy policy treats Baidu as a processor acting for the customer, but no public Qianfan page states whether API inputs train ERNIE, and no zero-retention option is published. Mainland traffic is processed in China under Chinese content rules.
- Cost at scale
- About ¥4 input and ¥18 output per million tokens up to 32K prompts. A million requests of 2K input and 500 output tokens cost about ¥17,000; on the international platform, ERNIE 5.0 is $1.40/$5.60 per million.
- Limits
- 128K context with up to 119K input and 65,536 output tokens; text only on the API. Not yet in the international Qianfan catalogue; sign-up may need a Chinese phone number.
What's good
- Fourth worldwide on LMArena's Search Arena at launch, first among Chinese models
- 99.6 on AIME26 with tools, per Baidu
- About ¥4 per million input tokens on Qianfan
- Free to use in Baidu's ERNIE assistant
What's not
- Closed weights and no published parameter counts
- API is text only with a 128K context
- Priced in yuan and not yet in Qianfan's international catalogue
- No public statement on whether API inputs are used for training
Best for
Teams building for Chinese-language users on Baidu's cloud who want strong search-grounded answers at a low token price.
ERNIE 5.1 alternatives
ERNIE 5.1: common questions
- Is ERNIE 5.1 worth it?
- Cheap to train and good at search-backed answers and maths, but closed, text-only on the API and still hard to buy outside China. We rate it 3.7 out of 5.
- How much does ERNIE 5.1 cost?
- Qianfan (mainland China): ¥0.004 input / ¥0.018 output per 1,000 tokens up to 32K, ¥0.006 / ¥0.022 from 32K to 128K. No official dollar price; the international catalogue lists ERNIE 5.0 at $1.40 / $5.60 per 1M tokens. Free in the ERNIE assistant.
- What are the downsides of ERNIE 5.1?
- Closed weights and no published parameter counts; aPI is text only with a 128K context; priced in yuan and not yet in Qianfan's international catalogue; no public statement on whether API inputs are used for training.
- Who is ERNIE 5.1 best for?
- Teams building for Chinese-language users on Baidu's cloud who want strong search-grounded answers at a low token price.
- How much does ERNIE 5.1 cost for a team or in production?
- About ¥4 input and ¥18 output per million tokens up to 32K prompts. A million requests of 2K input and 500 output tokens cost about ¥17,000; on the international platform, ERNIE 5.0 is $1.40/$5.60 per million.
- Is ERNIE 5.1 safe for company data?
- Closed weights. Baidu's international cloud privacy policy treats Baidu as a processor acting for the customer, but no public Qianfan page states whether API inputs train ERNIE, and no zero-retention option is published. Mainland traffic is processed in China under Chinese content rules.
- What are the best ERNIE 5.1 alternatives?
- The closest alternatives we have reviewed are Qwen3.8-Max, DeepSeek-V4-Pro, GLM-5.3 and MiMo-V2.6-Pro.
Answers checked Oct 25, 2026.