Experience stronger Korean fluency in the new Solar Pro & Mini

Upstage has released new versions of Solar Pro and Solar Mini, delivering major upgrades for smoother, clearer, and more natural Korean—ideal for Korean-first AI services.

Lucy Park

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Products

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April 28, 2025

At Upstage, we're dedicated to building AI models that truly understand and communicate in multiple languages, and Korean is one of the most important languages we consider. With the recent update of Solar Pro and Solar Mini (released Apr 22), we're excited to introduce major improvements in Korean fluency, across a wide range of use cases.

A leap forward in Korean fluency

Korean fluency is more than just grammar—it's about sounding natural, clear, and aligned with the user's intent. Our internal metric, ko-fluency tracks exactly that—and both Solar Pro and Mini saw significant upgrades in this release.

Solar Pro: Increased from 74.4 to 82.0 by +7.6 points, resulting in smoother, more natural conversations.
Solar Mini: Increased from 81.2 to 82.1 by +0.9 points, a meaningful gain at this scale.

An example of improvement in Korean fluency.

Solar Pro: Even stronger for Korean use cases

Comparison between Solar Pro, Exaone and HCX. Note that Ko-MT-Bench and Ko-MMLU are not publicly available. Ko-MT-Bench measures an LLM’s Korean conversational ability through multi-turn dialogues covering topics like coding, reasoning, mathematics, knowledge, and role-playing. Ko-MMLU is a Korean multitask benchmark designed to evaluate expert-level knowledge, and also one of the key datasets used in the Open Ko-LLM Leaderboard.

Solar Pro continues to be our top-tier model for enterprise-grade reasoning and structured output. This update makes it even more powerful for Korean users, including:

Major benchmark improvements, including Ko-MT-Bench from 71.8 → 81.0 (+9.2)
Sharper and cleaner outputs: Better summaries, clearer writing, and a more confident tone.