In marketing terms, a daily budget is used in regards to Google AdWords and similar pay-per-click campaigns. This type of budget refers to the average maximum amount of money that will be spent on a given day for a particular campaign. Custom budgets will need to be set for any additional campaigns. The budget sets a limit on what you can spend on bids per day as to reconcile your AdWords account to your overall marketing budget. The daily budget will affect the performance of a campaign. The budget that is set does not mean you will spend that exact amount each day. The daily budget is not a fixed cost, rather it is a variable cost; it is dependent on campaign performance and bidding strategy.
A daily budget can be exceeded by 20% on any given day, however, the exceeded cost will be compensated for throughout the month by other days cost falling below the daily budget. It is more practical to look at the daily budget in terms of a monthly budget by calculating the daily budget by the average number of days in a month which is 30.4. Below is an example.
Company XYZ has a daily budget of $50.
Though Company XYZ will spend upwards of $60 ($50*1.20) on any given day, however, they will never spend more than $1520 per month given their daily budget of $50.