The short answer
For most accounts in 2025, the highest-reach windows are:
- Tuesday–Thursday, 11 AM – 1 PM (lunch scroll)
- Sunday evenings, 7 PM – 9 PM (week-prep scroll)
Why "best time" depends on your audience
Your audience timezone matters more than any global average. Open Instagram Insights → Audience → Most Active Times. Post 30 minutes before that peak.
Combine with a free engagement boost
Posting at the right time + a small free likes boost in the first hour signals to the algorithm that this post deserves wider reach.