Most owners can tell you how much they spent on marketing last month. Fewer can tell you what it actually cost to land each customer. This spreadsheet tracks your spend against your leads and calculates your cost per lead automatically, so you know which channels are actually working and which ones are quietly draining the budget.

Update it monthly and the pattern shows itself. If a channel's CPL creeps past what a customer is worth to keep, that's not a hunch anymore, it's a number you can act on. Keep your team looking at the same numbers and marketing decisions stop being a guess.