| name | ad-spend-calculator |
| description | Calculates ad spend budgets based on revenue goals, conversion rates, and cost-per-acquisition targets. Use when planning how much to spend on ads to hit revenue targets. |
| allowed-tools | Read Write Glob |
| metadata | {"author":"matthewhitcham","version":"1.0"} |
Ad Spend Calculator
When to Use This Skill
Use this skill when you need to:
- Calculate how much ad spend is needed to hit a revenue goal
- Determine viable CPA targets based on product margins
- Build a budget allocation plan across platforms and campaigns
- Model different spend scenarios to find the optimal investment level
DO NOT use this skill for organic marketing budgets, general business budgeting, or ad creative strategy. This is specifically for calculating paid advertising budgets.
Core Principle
AD SPEND IS AN INVESTMENT EQUATION — EVERY DOLLAR IN MUST PRODUCE A MEASURABLE RETURN, AND THE MATH MUST WORK BEFORE THE FIRST DOLLAR IS SPENT.
Phase 1: Inputs
Required Inputs
| Input | What to Ask | Default |
|---|
| Revenue goal | "What is your monthly revenue target from ads?" | No default — must be provided |
| Average order value (AOV) | "What is your average sale or order value?" | No default — must be provided |
| Profit margin | "What is your profit margin per sale (after COGS)?" | 60% |
| Current conversion rate | "What percentage of ad clicks convert to sales?" | 2% (industry average) |
| Current CPC | "What is your average cost per click?" | $1.50 (estimate) |
| Ad platforms | "Where are you running ads?" | Meta + Google |
GATE: Do not proceed without revenue goal and AOV.
Phase 2: Core Calculations
Funnel Math
## Ad Spend Calculator
### Inputs
- Monthly revenue goal: $[X]
- Average order value: $[X]
- Profit margin: [X]%
- Conversion rate: [X]%
- Average CPC: $[X]
### Calculated Metrics
| Metric | Value | Formula |
|--------|-------|---------|
| Sales needed | [X] | Revenue goal / AOV |
| Clicks needed | [X] | Sales needed / Conversion rate |
| Required ad spend | $[X] | Clicks needed x CPC |
| Cost per acquisition (CPA) | $[X] | Ad spend / Sales needed |
| Max viable CPA | $[X] | AOV x Profit margin |
| ROAS needed | [X]x | Revenue goal / Ad spend |
| Profit after ad spend | $[X] | Revenue - COGS - Ad spend |
Viability Check
Flag these automatically:
- CPA exceeds 50% of AOV — warning: tight margins
- CPA exceeds profit margin — alert: losing money on every sale
- Required ROAS exceeds 5x — alert: very aggressive, may not be achievable
- Monthly spend exceeds $10K — note: recommend phased scaling
Phase 3: Scenario Modeling
Present 3 scenarios so the user can choose their risk level.
## Scenarios
### Conservative (Lower spend, proven channels only)
| Metric | Value |
|--------|-------|
| Monthly spend | $[X] |
| Expected sales | [X] |
| Expected revenue | $[X] |
| Expected ROAS | [X]x |
| Profit after ads | $[X] |
### Base Case (Moderate spend, balanced approach)
| Metric | Value |
|--------|-------|
### Aggressive (Higher spend, scaling mode)
| Metric | Value |
|--------|-------|
Platform Allocation
## Budget Allocation by Platform
| Platform | % of Budget | Monthly Spend | Expected ROAS | Rationale |
|----------|-------------|---------------|---------------|-----------|
| Meta | [X]% | $[X] | [X]x | [Why] |
| Google | [X]% | $[X] | [X]x | [Why] |
| [Other] | [X]% | $[X] | [X]x | [Why] |
Phase 4: Action Plan
Monthly Budget Calendar
## Monthly Spend Plan
Week 1: $[X] — Testing phase (3-5 ad sets, $X/day each)
Week 2: $[X] — Evaluate, pause underperformers
Week 3: $[X] — Scale winners, increase daily budgets
Week 4: $[X] — Maintain and optimize
Total: $[X]
Breakeven Checklist
- [ ] CPA is below max viable CPA ($[X])
- [ ] ROAS exceeds breakeven ([X]x)
- [ ] Daily budget supports statistical significance ($[X]/day minimum)
- [ ] Conversion tracking is installed and verified
- [ ] Landing page conversion rate is at or above [X]%
Example: Course Creator ($10K/month Goal)
Inputs: AOV = $197, margin = 85%, conversion rate = 3%, CPC = $2.00
Results:
- Sales needed: 51/month
- Clicks needed: 1,700
- Required spend: $3,400/month
- CPA: $66.70
- Max viable CPA: $167.45 (profitable at current CPA)
- ROAS: 2.94x
- Profit after ads: $5,117/month
Verdict: Math works well. CPA is 40% of max viable CPA — room to scale.
Anti-Patterns
- Ignoring profit margin — revenue ROAS is meaningless without margin context. A 3x ROAS on 20% margins is break-even.
- Using industry-average conversion rates without testing — always note that defaults are estimates. Real data replaces assumptions.
- Calculating without including all costs — include platform fees, creative costs, landing page tools, and team time.
- Linear scaling assumptions — doubling spend rarely doubles results. Factor in diminishing returns at higher spend levels.
- No minimum daily budget check — platforms need $20-50/day minimum per ad set for optimization. If budget does not support this, reduce ad sets.
Recovery
- Math does not work (CPA > margin): Show the user which lever to pull — increase AOV, improve conversion rate, lower CPC, or add upsells/LTV to change the equation.
- No historical data: Use industry benchmarks but clearly label them as estimates. Recommend a $500-1,000 test budget before committing to the full calculated spend.
- Multiple products at different price points: Calculate separately for each product, then create a blended portfolio view.
- Revenue goal seems unrealistic: Show the spend required and let the user decide. If it requires a ROAS above 5x with no historical data, flag the risk explicitly.
