Understand the numbers
How to use this calculator
Keep the time period consistent
Use spend through the end of the last complete day, and count only those completed days. Mixing today’s partial spend with a full elapsed day understates your pace. For a custom campaign period, enter its full duration rather than the calendar month.
Compare recent pace with the whole period
Enter a recent window, such as the last seven completed days, and the spend within it. Both windows must end at the same reporting cutoff. The recent projection adds actual spend to an estimate for the remaining days, so earlier spend is never counted twice. A short window can be noisy; compare both projections before changing budgets. Clear both optional fields to use only the period average.
Allow for uneven delivery
Weekends, seasonality and launches can make uneven spend sensible. These projections hold daily spend constant and do not predict auction demand. The allowance and percentage change are planning figures, not automatic platform budget changes or spending guarantees. A zero recent pace has no meaningful percentage adjustment; use the cash allowance instead.
A worked example
With a £5,000 budget, £2,800 spent and 15 of 30 days complete, the daily allowance is £146.67 and the whole-period projection is £5,600. If the last seven days cost £1,050, the recent pace is £150 per day and projects £5,050. Reducing that recent pace by about 2.22% would use the remaining budget evenly.