We recommend 2-3 days for most Instagram giveaway campaigns. If you boost the Instagram post for longer, sustained engagement a longer campaign (e.g. up to 7 days) may attract more entries.
How long your Instagram giveaway should last depends on multiple factors, but most giveaways on Instagram should be 48-72 hours up to 1 week. If your goal is to generate urgency and create a spike in engagement, 24hrs may work better for you. For more extensive collaborations where it takes more time to mobilize audiences, you can use extended giveaway periods (e.g., 1 week). These generally also have more expensive prizes.
Remember to include your giveaway's start and end date and time (including time zone) in your giveaway caption.
Another factor in choosing your giveaway length is the size of your audience. For example, small followings may want to run 1-week-long giveaways to maximize reach. Larger followings can do either long or short giveaways due to their bigger audience.