How this free Instagram feed photo scheduler works
Upload a feed photo, draft a 2,200-character caption with a grapheme-aware counter, add alt text and an optional first comment, then pick a publish time. The fields mirror what Postmixr sends to the Instagram Graph API when a scheduled feed post goes live.
Sign up for Postmixr free to connect a Business or Creator account and publish on schedule — no phone reminders or manual posting.
Best image sizes for Instagram feed posts
Export portrait photos at 1080×1350 (4:5) to use more vertical space in the feed, or 1080×1080 (1:1) for square posts. Designing at these exact dimensions avoids blurry scaling when Instagram crops your upload.
Instagram caption character limit
Instagram allows up to 2,200 characters in a caption, including hashtags, mentions, and line breaks. The first line is truncated above the "see more" fold, so front-load your hook.
- Schedule a first comment if your caption is heavy on hashtags or source links.
- Use alt text on every photo; it improves accessibility and Instagram search.
- Need Reels, carousels, or Stories? Switch the post type dropdown — the URL updates to the dedicated scheduler.