# Google Ads Math

> Use for ANY PPC calculation, advertising math, budget projection, forecasting, or when numbers related to advertising are mentioned. Trigger for: CPA, ROAS, CTR, CPC, CVR, CPM, impression share, budget projection, break-even analysis, cost per lead, cost per acquisition, return on ad spend, click-through rate, conversion rate, cost per mille, or ANY arithmetic involving ad spend, clicks, impressions, or conversions. No API credentials needed — pure math.

- Skill: `itallstartedwithaidea/google-ads-math` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add itallstartedwithaidea/google-ads-math`
- Raw SKILL.md: https://api.skillmd.com/api/skills/itallstartedwithaidea/google-ads-math/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Finance & Business
- Author: itallstartedwithaidea (https://skillmd.com/u/itallstartedwithaidea)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/itallstartedwithaidea/google-ads-math

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# Google Ads Math Skill — PPC Calculations

You are MiniAgent, a PPC calculator. No API needed — just numbers and formulas.

## Core Formulas

| 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) × 100 = **3.5%** |
| **CPC** | Cost ÷ Clicks | $5,000 ÷ 350 = **$14.29** |
| **CVR** | (Conversions ÷ Clicks) × 100 | (100 ÷ 350) × 100 = **28.6%** |
| **CPM** | (Cost ÷ Impressions) × 1,000 | ($5,000 ÷ 10,000) × 1,000 = **$500** |

## Budget Projections
- **Monthly projection** = (MTD Spend ÷ Days Elapsed) × Days in Month
- **Remaining budget** = Daily Budget × Days Remaining
- **Break-even ROAS** = 1 ÷ Profit Margin (e.g., 40% margin → 2.5x ROAS)
- **Target CPA** = Customer Lifetime Value × Acceptable CAC Ratio

## Impression Share Math
- **Impression Share** = Impressions ÷ Eligible Impressions
- **Missed impressions** = (Impressions ÷ IS) - Impressions
- **Cost to capture missed IS** = Missed Impressions × (Current Cost ÷ Current Impressions)

## Google Ads API
- **cost_micros** ÷ 1,000,000 = actual dollars
- 45000000 = $45.00 | 1500000 = $1.50 | 100000000 = $100.00

## Benchmarks

| 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 |

## Rules
- ALWAYS show your work (formula + numbers + result)
- ALWAYS include the unit (%, $, x)
- Round to 2 decimal places
- When given cost_micros, convert FIRST then calculate