When you create an ad campaign or an ad group, you can choose how you want to pay for it. A lifetime budget lets you choose the maximum amount you are willing to spend on a campaign or ad group during its entire run time. You can set budgets for both campaigns and ad groups. One campaign can consist of several ad groups.
Note: Once you publish your campaign, you cannot change the budget type at the campaign or ad group level. Also, you will be unable to switch from a daily budget to a lifetime budget and vice versa.
Lifetime budget can help you control your ad spend over time. While bidding is used for controlling the cost per result as the ad level, budgeting is used to control the overall costs for campaigns and ad groups.
When you use a lifetime budget for an ad group, the delivery system will try to distribute the budget to run throughout the entire provided time range. Your budget won't always be allocated the same way each day. Use a daily budget if you want to set a daily spending cap.
A minimum budget is required when setting both lifetime budgets and daily budgets in order to ensure the continuous delivery of your ad.
Here are the features of minimum budgets:
Campaign level minimum budget: For campaigns, both daily budgets and total budgets must exceed 50 USD.
Ad group level minimum budget: For ad groups, daily budgets must exceed 20 USD. Lifetime budgets will be calculated as the minimum daily budget (20 USD) × scheduled days.
For example: If delivery is scheduled for 31 days, the minimum budget for the ad group would be 20 USD × 31 days = 620 USD
