Explain the primary difference in how Meta delivers ads with a daily budget versus a lifetime budget, specifically regarding pacing and spend consistency throughout the campaign duration.

When delivering ads, Meta’s primary difference between a daily budget and a lifetime budget lies in their pacing strategy and the resulting spend consistency throughout the campaign duration. "Pacing" refers to how Meta's ad delivery system distributes your budget over time to achieve campaign goals. "Spend consistency" describes the predictability and uniformity of the amount spent on a day-to-day basis.

When you set a daily budget, you instruct Meta to spend, on average, that specified amount each day. Meta's ad delivery system, which manages "pacing," aims to distribute your spending relatively evenly throughout each 24-hour period. For example, if you set a $100 daily budget, Meta will attempt to spend approximately $100 every day the campaign runs. This means your "spend consistency" from one day to the next will generally be high; the daily spend amount will remain fairly stable. While Meta might slightly overspend by up to 25% on a given day if it identifies a strong opportunity for results, like a period when your audience is highly engaged or conversions are likely, it will compensate by underspending on other days within a seven-day rolling window to ensure the average daily spend adheres to your set budget. This budget type is ideal for maintaining a consistent presence and predictable daily expenditure over an indefinite or defined campaign duration.

In contrast, a lifetime budget specifies the total amount you want to spend over the entire duration of your campaign, which requires setting both a start and an end date. With a lifetime budget, Meta's pacing system has much greater flexibility in how it allocates your spend across the campaign's lifespan. Instead of aiming for a consistent daily spend, the system's primary goal is to achieve the best possible overall results within the total budget and timeframe. This means Meta might spend significantly more on certain days or hours when it detects high-performing opportunities – for example, when your audience is most active or when the cost per result is temporarily lower. Conversely, it might spend very little or even nothing on other days if conditions are not optimal. Consequently, the "spend consistency" on a day-to-day basis will be highly variable; you might see $500 spent on one day and only $50 on another, but the total spent by the campaign's end will not exceed your specified lifetime budget. This budget type is beneficial when you have a fixed total budget for a specific campaign duration and prioritize maximizing overall results, even if it means inconsistent daily spending.

The primary difference, therefore, lies in the pacing philosophy and the resulting spend consistency. A daily budget prioritizes a consistent daily spend, pacing expenditure relatively evenly throughout each day and across the campaign's duration, leading to predictable day-to-day costs. Conversely, a lifetime budget prioritizes maximizing overall campaign results within a fixed total budget and defined timeframe, allowing Meta's system to dynamically allocate spend across days based on performance opportunities, which results in highly inconsistent daily spending but ensures the total budget is not exceeded by the campaign's end.