How Budget Allocation redistributes campaign budgets
Budget Allocation recalculates each included campaign’s daily budget once per day. It starts with campaign spend, adjusts the budget to match the allocation group’s total daily budget, then shifts a limited amount toward better-performing campaigns.
This process applies to both daily-cap and monthly-cap allocation groups.
When budgets are recalculated
Budgets are recalculated once per day, and the calculation usually runs at 00:00 in the campaign group’s timezone. In rare cases where this is not possible, UTC is used instead. The same timezone is used for performance lookback periods, including the previous day’s spend.
Budget Allocation normally keeps the allocation group’s total daily budget fixed. It changes how that amount is divided across the included campaigns.
For cases where bid safeguards can increase the final allocated total, see About minimum daily budgets and bid safeguards.
The daily calculation process
The calculation follows these main steps:
- Start with each campaign’s previous-day spend.
- Apply a 40% floor to low-spending campaigns.
- Distribute any remaining budget or remove any excess spend.
- Shift a limited amount toward better-performing campaigns.
- Apply campaign bid safeguards.
The first three steps depend on whether the campaigns spent less or more than the allocation group’s total daily budget.
How under-spend is handled
Under-spend occurs when the included campaigns spent less than the total daily budget during the previous day.
In this case, Budget Allocation distributes the remaining amount.
Example
Assume an allocation group has a total daily budget of $300 across three campaigns.
|
Campaign |
Previous budget |
Previous-day spend |
Budget spent |
|
A |
$150 |
$135 |
90% |
|
B |
$100 |
$20 |
20% |
|
C |
$50 |
$45 |
90% |
The campaigns spent $200 in total. This leaves $100 to redistribute.
Step 1: Start with previous-day spend
Each campaign is initially assigned what it spent:
|
Campaign |
Initial amount |
|
A |
$135 |
|
B |
$20 |
|
C |
$45 |
Step 2: Apply the 40% floor
A campaign’s amount is not reduced below 40% of its previous budget. This prevents a low-spending campaign from having its budget reduced to near zero based on one day of limited activity.
Campaign B spent 20% of its previous budget. Its amount is therefore raised to 40% of $100, which is $40.
The updated amounts are:
|
Campaign |
Amount after the floor |
|
A |
$135 |
|
B |
$40 |
|
C |
$45 |
The total is now $220, leaving $80 to distribute.
Step 3: Distribute the remaining budget
Budget Allocation uses the following order:
- If one or more campaigns spent at least 90% of their budgets, the remaining amount goes to those campaigns first.
- If no campaign reached 90%, but one or more spent at least 40%, the amount goes to those campaigns.
- If no campaign reached 40%, the amount is distributed across all campaigns.
The amount is distributed in proportion to campaign spend.
In this example, campaigns A and C both spent 90% of their budgets. Their previous-day spend was $135 and $45, which is a 3-to-1 ratio.
The remaining $80 is divided as follows:
- Campaign A receives $60.
- Campaign C receives $20.
The result before the KPI-based adjustment is:
|
Campaign |
New amount |
|
A |
$195 |
|
B |
$40 |
|
C |
$65 |
|
Total |
$300 |
How over-spend is handled
Over-spend occurs when the included campaigns spend more than the total daily budget during the previous day. This can happen because of how Apple Ads paces daily budgets.
In this case, Budget Allocation removes the excess amount in proportion to campaign spend.
Example
Assume the same $300 total daily budget.
|
Campaign |
Previous budget |
Previous-day spend |
|
A |
$150 |
$180 |
|
B |
$100 |
$120 |
|
C |
$50 |
$60 |
The campaigns spent $360 in total. This is $60 above the allocation group’s daily budget.
Step 1: Start with previous-day spend
The initial amounts are:
|
Campaign |
Initial amount |
|
A |
$180 |
|
B |
$120 |
|
C |
$60 |
Step 2: Apply the 40% floor
No campaign falls below 40% of its previous budget, so no adjustment is needed.
Step 3: Remove the excess
The $60 excess is removed in proportion to each campaign’s share of total spend:
- Campaign A contributed 50% of spend and is reduced by $30.
- Campaign B contributed about 33% of spend and is reduced by $20.
- Campaign C contributed about 17% of spend and is reduced by $10.
The result before the KPI-based adjustment is:
|
Campaign |
New amount |
|
A |
$150 |
|
B |
$100 |
|
C |
$50 |
|
Total |
$300 |
What happens after the initial distribution
After the under-spend or over-spend adjustment, Budget Allocation makes two more checks.
KPI-based adjustment
Campaigns are ranked using the KPI selected for the allocation group:
- CPA uses cost per install.
- CPI uses cost per attributed install.
- CPG uses cost per the selected goal.
Budget Allocation then moves a limited amount from weaker-performing campaigns to better-performing campaigns. For the complete ranking and transfer process, see How KPI performance affects budget distribution.
Bid safeguards
The final amount for each campaign is checked against its required bid minimum.
If a calculated campaign budget is below its highest Keyword bid or Ad Group Default CPT bid, the campaign budget is raised to meet the higher value.
For the minimum calculation and possible budget overages, see About minimum daily budgets and bid safeguards.
Related links
- How KPI performance affects budget distribution
- About minimum daily budgets and bid safeguards
- About daily and monthly caps
- About Budget Allocation KPIs, goals, and attribution settings
Need more help?
If you have further questions on the process, contact your dedicated Customer Success Manager or contact the support team via live chat.