How long should an average blog be?

There is no universal correct blog length. The right answer comes from one place: the average length of the pages currently ranking in the top 10 for your target keyword. Google has already told you what works for that query, and the SERP is the answer key.

Rough guidance by content type, based on what ranks today:

• -Definitional or FAQ-style ("What is X?"): 600-1,200 words. Short, direct, optimized for featured snippets.
• -Listicles ("10 best X tools"): 1,500-2,500 words. Each item gets 100-200 words of substance.
• -How-to guides and tutorials: 2,000-3,000 words. Steps need depth and screenshots.
• -Pillar pages and topic-cluster hubs: 3,000-5,000 words. Comprehensive coverage of a subtopic family.
• -Opinion or thought-leadership: whatever it takes. Length matters less than originality of argument.

Two failure modes to avoid: padding a 600-word answer to 2,000 words to hit a number (Google detects fluff), and crunching a 3,000-word topic into 800 words to save time (the SERP eats you). Match the length of the top 5 results, then add one thing they all miss. That is the formula.