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.
Treat a straight line as a reference
Weekends, seasonal demand and launch dates can make uneven delivery sensible. The forecast assumes your average spend to date continues. The remaining daily allowance is an arithmetic guide, not a platform setting or a spending guarantee.
A worked example
Halfway through a 30-day period, a £5,000 budget has a straight-line spend target of £2,500. If £2,800 has been spent, spend is £300 ahead of plan. The remaining £2,200 allows about £146.67 per day for the final 15 days.