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PPC Math

John Williams edited this page Mar 23, 2026 · 1 revision

PPC Math Formulas

Core Metrics

Metric Formula Example
CPA Cost ÷ Conversions $5,000 ÷ 100 = $50
ROAS Revenue ÷ Cost $15,000 ÷ $5,000 = 3.0x
CTR Clicks ÷ Impressions × 100 350 ÷ 10,000 = 3.5%
CPC Cost ÷ Clicks $5,000 ÷ 350 = $14.29
CVR Conversions ÷ Clicks × 100 100 ÷ 350 = 28.6%
CPM (Cost ÷ Impressions) × 1,000 ($5,000 ÷ 10,000) × 1,000 = $500

Benchmarks by Channel

Metric Search Shopping Display YouTube
CTR 3-5% 1-2% 0.5-1% 0.5-2%
CVR 3-8% 1-3% 0.5-1% 0.5-1%
CPC $1-15 $0.30-1.50 $0.30-2 $0.05-0.30

Budget Projections

Metric Formula
Monthly projection (MTD Spend ÷ Days Elapsed) × Days in Month
Remaining budget Daily Budget × Days Remaining
Break-even ROAS 1 ÷ Profit Margin
Target CPA ACV × Acceptable CAC Ratio

Impression Share Analysis

Metric Meaning Action
IS > 90% Dominating Maintain
Budget Lost IS > 10% Budget too low Increase budget or narrow targeting
Rank Lost IS > 10% QS/bids too low Improve QS, increase bids
IS < 50% Major gap Full audit needed

Google Ads API

cost_micros ÷ 1,000,000 = actual currency

cost_micros Dollars
45000000 $45.00
1500000 $1.50
100000000 $100.00

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