PPC Basics: CPC, CPM, Spend, and ROI
Paid media math is arithmetic on assumptions you control: clicks or impressions, unit price, conversion rate, and revenue. This guide maps CPC and CPM to the worksheets on Free Calculator Hub—and flags what platforms still decide in auction.
CPC vs CPM in one sentence
CPC prices the click; CPM prices one thousand impressions. Both become campaign spend once you multiply by volume. ROI and ROAS then compare that spend (plus optional variable costs) to modeled revenue.
A practical planning loop
Pick the pricing unit
Use CPC when you buy clicks; use CPM when you buy impressions.
Attach a conversion rate
Conversions ≈ clicks × (CVR ÷ 100), or impressions × CTR × CVR when you model the full funnel.
Compare spend to revenue
ROI uses profit ÷ spend; ROAS uses revenue ÷ spend. Keep the definitions consistent across reports.
Stress-test the budget
Raise CPC or lower CVR and re-run before you commit spend.
Where affiliate math fits
Affiliate commissions are often a revenue or cost share after a click converts. Model paid acquisition with CPC/CPM tools first, then estimate commission payouts separately so you do not double-count spend.