The rules for a minimum daily budget are set by Facebook.
They require a minimum budget to strive for consistent delivery of your ads. Minimum budgets are calculated as a daily amount and apply whether an ad set is using a daily or lifetime budget and to both types of bidding.
Ad sets with budgets in these currencies (USD, AUD, CAD, SGD, JPY, NZD, TWD, EUR, CHF, SEK, HKD, GBP, ILS, NOK, KRW, DKK) must follow these requirements:
- When optimising for impressions, the budget should be at least $1 a day.
- When optimising for Clicks, Likes, Video views, or Post engagement, the budget should be at least $5 a day.
- When optimising for low frequency events like offer claims or app installs, the budget should be at least $40 a day.
Important: When using manual bidding in combination with a daily budget, the ad set is required to meet all of the above minimums, and its budget must be at least five times bigger than its bid. For example, if your ad set gets charged for app installs and has a manual bid of $10, its daily budget must be at least $50. An ad set that is identical, but uses automatic bidding, would have to have a daily budget of at least $40.
It's also possible to use a spend cap when building your campaign. This means that, although your campaign budget might need to be higher than your actual budget, you can still put a cap on your spend, which can be lower than the minimum budget as decided by Facebook.