GPT-5 Medium vs Mercury 3
GPT-5 Medium and Mercury 3 are closely matched at 29.3 and 36.1 on the LLM Stats Score. Mercury 3 is 21.2x cheaper per token.
OpenAI · Inception · Updated for 2026
Which is better?
GPT-5 Medium and Mercury 3 are closely matched on the overall LLM Stats Score at 29.3 and 36.1.
In the 1 individual benchmarks reported for both models, Mercury 3 wins 1; this is a narrower head-to-head signal than the composite indexes.
On price, Mercury 3 is roughly 21.2x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.
Mercury 3 also accepts a larger context window (1,000,000 input tokens), making it the stronger choice for long documents and large codebases.
Based on current LLM Stats indexes, shared benchmarks, pricing, and model metadata for 2026.
Choose GPT-5 Medium
- you want predictable pricing at $1.25/M input and $10.00/M output
Choose Mercury 3
- you value its reported benchmark strengths — it wins 1 of 1 exact shared results
- cost matters — it's about 21.2x cheaper per token
- you process long inputs — it offers a 1,000,000 token context window
- you want the most recent training data — it shipped Oct 2026
At a glance
The differences that matter most.
Individual benchmarks
2 reported for GPT-5 Medium · 12 for Mercury 3
GPT-5 Medium outperforms in 0 benchmarks, while Mercury 3 is better at 1 benchmark (GPQA).
Mercury 3 significantly outperforms across most benchmarks.
Human preference
Blind head-to-head votes and playground preference scores
Pricing Analysis
Price comparison per million tokens
For input processing, GPT-5 Medium ($1.25/1M tokens) is 12.5x more expensive than Mercury 3 ($0.10/1M tokens).
For output processing, GPT-5 Medium ($10.00/1M tokens) is 28.6x more expensive than Mercury 3 ($0.35/1M tokens).
In conclusion, GPT-5 Medium is more expensive than Mercury 3.*
* Using a 3:1 ratio of input to output tokens
Context Window
Maximum input and output token capacity
Mercury 3 accepts 1,000,000 input tokens compared to GPT-5 Medium's 400,000 tokens. Mercury 3 can generate longer responses up to 131,072 tokens, while GPT-5 Medium is limited to 128,000 tokens.
Input capabilities
Documented input modalities across available providers
GPT-5 Medium supports multimodal inputs, whereas Mercury 3 does not.
GPT-5 Medium can handle both text and other forms of data like images, making it suitable for multimodal applications.
GPT-5 Medium
Mercury 3
License
Usage and distribution terms
Both models are licensed under proprietary licenses.
Both models have usage restrictions defined by their respective organizations.
Proprietary
Closed source
Proprietary
Closed source
Release Timeline
When each model was launched
GPT-5 Medium was released on 2025-08-07, while Mercury 3 was released on 2026-10-19.
Mercury 3 is 15 months newer than GPT-5 Medium.
Aug 7, 2025
1.2 years ago
Oct 19, 2026
0 days ago
1.2yr newerKnowledge Cutoff
When training data ends
GPT-5 Medium has a documented knowledge cutoff of 2024-09-30, while Mercury 3's cutoff date is not specified.
We can confirm GPT-5 Medium's training data extends to 2024-09-30, but cannot make a direct comparison without Mercury 3's cutoff date.
Sep 2024
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Provider Availability
GPT-5 Medium is available from OpenAI. Mercury 3 is available from Inception.
GPT-5 Medium
Mercury 3
Outputs Comparison
Judge for yourself.
Run your own prompts against GPT-5 Medium and Mercury 3 side-by-side, then vote on the output you prefer.
FAQ
Common questions about GPT-5 Medium vs Mercury 3.