How Do You Calculate the CAC of a Giveaway?

Add up the full campaign cost — prize, platform plan, and operational time — then divide by the number of customers it produced (not entries, customers):

Giveaway CAC = (Prize + Platform fees + Operational time) ÷ Customers won

For example: a $500 prize, a platform plan around $79, and roughly $200 of setup time comes to about $779. If that campaign converts 60 customers, your CAC is roughly $13 — and it keeps falling as referrals bring in entries you never paid for.

That last point is the real difference from paid ads. A giveaway's cost is mostly fixed up front, so every shared, viral entry drives the per-customer cost down. Paid CAC stays roughly flat no matter how long you run, because you pay for each new customer at auction prices that only rise.

	Paid ads	Giveaway
Formula	(Ad spend + creative + management) ÷ customers	(Prize + platform + ops) ÷ customers
Cost behaviour	Flat per customer; scales linearly with spend	Mostly fixed up front; per-customer cost falls as it's shared
Costs to add back	Rising CPCs, signal loss, creative	Prize, fulfillment, prize-hunters

To compare the two fairly, always put back the costs each side tends to hide before you judge a winner.