A micro-influencer is an influencer with roughly 10,000 to 50,000 followers. This tier sits between nano-influencers and mid-tier influencers, and is often the entry point for brands running their first paid influencer campaigns.

The 10,000–50,000 range is a general industry convention rather than a fixed rule, and it can shift depending on platform and category. What defines the tier in practice is the combination of a large enough audience to reach beyond the influencer's immediate circle, while remaining small enough that engagement rates typically stay higher than on larger accounts.

Compared to nano-influencers, micro-influencers offer more reach per post but usually at a somewhat lower engagement rate. Compared to mid-tier and macro-influencers, they cost less per post and tend to have a more clearly defined niche audience, at the cost of lower overall reach.

Micro-influencers let brands run campaigns across many creators for a similar budget to one macro-influencer post, spreading risk across multiple audiences instead of relying on a single partnership. They're also a common fit for niche products, since micro-influencers often build their following around a specific topic — fitness, skincare, personal finance that lines up closely with a brand's target customer.