Facebook Ads Budget Calculator: Budget to Goal, or Goal to Budget

Every Facebook and Instagram ads budget conversation eventually comes down to the same two questions: what will this budget get me, or what budget do I need to hit a number. This calculator answers either one. Switch modes depending on whether you are starting from a fixed budget or a results goal, and it converts between monthly spend, daily spend and expected results using your target cost per result.

Two ways to plan a Facebook ads budget

In budget mode, enter what you plan to spend each month and your target cost per result, and the calculator divides one by the other to estimate how many leads, sales or sign-ups that should produce. In goal mode, enter how many results you need and the same target cost per result, and it multiplies them to tell you the monthly budget required. Both modes also show the equivalent daily budget, since that is what you will actually enter into Ads Manager.

Why Meta converts monthly budgets using 30.4 days

Meta's own Ads Manager converts a monthly budget to a daily budget by dividing by 30.4, the average number of days in a month across a full year, 365 divided by 12. Using a flat 30 slightly overstates your true monthly spend over a year, since months alternate between 28 and 31 days. This calculator uses the same 30.4 figure so the daily number here matches what you would set inside the platform.

Setting a realistic target cost per result

Cost per result varies enormously by objective, industry and audience competition, from a few dollars for a simple lead form in an easy niche to well over a hundred dollars for a high-value B2B demo request. If you have run campaigns before, pull your actual average cost per result from Ads Manager rather than guessing. If you have no history yet, start with a modest test budget, measure the real number, then come back and plug it in here for accurate planning going forward.