Daily budget fluctuations
User traffic fluctuates from day to day. To make up for these fluctuations and to ensure that your campaigns reach their potential, Google may allow up to 20% more impressions in one day than your daily budget specifies.
However, our system makes sure that in a given billing period, you're never charged more than the number of days in that billing period times your daily budget. For example, if you budget US$10 per day, and you're charged for a 30-day billing period, the maximum you would pay is US$300.
If Google overdelivers your ads too much, and you accrue more costs in a billing period than your budget allows, a credit will automatically be applied to your account. For instance, if you receive a credit for $5, and you've accrued $30 in costs in a given billing period, you'll only be charged for $25.
To see if you've received any overdelivery credits:
- Sign in to your Ad Exchange account at https://www.google.com/adxbuyer.
- Select the My Account tab.
- Make sure Billing Summary is selected in the shaded bar beneath the tabs.
- Click Campaign activity.
- To see activity for a particular month, click Campaign activity in the shaded section above the desired calendar month.
- To see activity for a particular day, click Campaign activity in the Description column next to the desired day.
- Any credits for excess activity will appear in the Overdelivery credit field.