# How budget changes take effect

When you change your average daily budget, you'll see these adjustments immediately in your account. Changing your average daily budget can impact how frequently your ads are shown, as well as how much you can be charged.

Google optimises your campaign spend for days of the month when you’re more likely to get clicks and conversions. When you change your average daily budget, Google will start serving your ads taking into account your recently changed budget. An increase in budget may be followed by an increase in spend, while a decrease may have the opposite effect.

## Budget changes can impact how much you can be charged

### Impact on daily spending limit

On the day that you make a change (or more than one change) to your average daily budget, your daily spending limit will be based on the highest average daily budget that you chose for that day. This means that for most campaigns you'll never be charged more than twice your highest average daily budget on that day.

#### Example

Let’s say that you have a campaign with an average daily budget of £10. On the same day, you first increase your budget to £50, and then lower it to £5. The daily spending limit for the day is going to be the highest of your average daily budgets multiplied by two, therefore £50 * 2 = £100.

### Impact on monthly spending limit

When you change your budget, your spend for the rest of the month won’t exceed your new average daily budget multiplied by the remaining days in the month.

#### Example

Let’s look at a monthly spending limit for November, which spans from 1 November to 30 November. On 1 November, you set an average daily budget of £5, for a monthly spending limit of £152 (£5 * 30.4). Then assume that, on 24 November, you’ve only spent £103 and you decide to increase your average daily budget for the remaining days of the month. You then change your average daily budget to £10. The maximum that you’ll be charged for the month of November will be:

£103 spent so far + (£10/day * 7 days remaining in November) = £173 monthly spending limit

## Putting everything together

When you change an average daily budget, two things are going to happen:

2. Your daily spending limit and your monthly spending limit are going to be updated accordingly.

### Single budget increase

Assume that you have a campaign that has been running since the beginning of September. At the beginning of September:

• Average daily budget: £10
• Daily spending limit = £10 * 2 = £20
• Monthly spending limit = £10 * 30.4 = £304

With five days left in the month (including the day the budget is edited) and £270 total spent, the average daily budget is increased to £50. This will result in:

• Average daily budget: £50
• Daily spending limit: £50 * 2 = £100
• Monthly spending limit = £270 + (£50/day * 5 remaining days in September) = £520

### Single budget decrease

Assume that you have a campaign that has been running since the beginning of September. At the beginning of September:

• Average daily budget: £10
• Daily spending limit = £10 * 2 = £20
• Monthly spending limit = £10 * 30.4 = £304

With 5 days left in the month (including the day the budget is edited) and £270 total spent, the average daily budget is decreased to £5. This will result in:

• Average daily budget: £5
• Daily spending limit for the day with the edit: £10 * 2 = £20

This is because we pick the highest daily budget for the day.

• Daily spending limit for remaining days of the month: £5 * 2 = £10
• Monthly spending limit = £270 + (£5/day * 5 remaining days in September) = £295
Note: The daily spending limit is updated keeping the highest average daily budget for the day, whereas the monthly spending limit only considers the latest average daily budget.

### Multiple edits on the same day

Assume that you have a campaign that has been running since the beginning of September. At the beginning of September:

• Average daily budget: £10
• Daily spending limit = £10 * 2 = £20
• Monthly spending limit = £10 * 30.4 = £304

With five days left in the month (including the day the budget is edited) and £270 total spent, the average daily budget is increased to £50. This will result in:

• Average daily budget: £50
• Daily spending limit: £50 * 2 = £100
• Monthly spending limit = £270 + (£50/day * 5 remaining days in September) = £520

On the same day, a few hours after the first edit and now £280 total spent, the average daily budget is decreased to £30. This will result in:

• Average daily budget: £30
• Daily spending limit for the day with the edit: £50 * 2 = £100

This is because we pick the highest daily budget for the day.

• Daily spending limit for remaining days of the month: £30 * 2 = £60
• Monthly spending limit = £280 + (£30/day * 5 remaining days in September) = £420

Note: Even if you don't deliberately change the average daily budget in your campaign, the following actions are considered budget changes (for computing the maximum amount you'll pay within a calendar month):

• Changing your campaign end date.

Find out how to select a time zone, and how it affects your budget cycle.