ads-math

PPC 财务计算器与建模

概念改编自 itallstartedwithaidea/google-ads-skills（PPC 数学）。

流程

1. 询问用户需要进行哪种计算（或根据上下文判断）
2. 收集所需输入（来自粘贴的数据、导出文件或口头描述）
3. 使用清晰的公式进行计算
4. 提供结果、解读和建议
5. 标出值得关注的指标或基准

计算器

1. CPA 计算器

CPA = Total Spend / Total Conversions

Inputs needed:
- Total ad spend (period)
- Total conversions (same period)

Output:
- CPA with period context
- CPA trend (if historical data provided)
- Comparison to industry benchmark (from benchmarks.md)

2. ROAS 计算器

ROAS = Revenue from Ads / Ad Spend
ROAS% = (Revenue - Spend) / Spend × 100

Inputs needed:
- Total ad spend
- Total revenue attributed to ads

Output:
- ROAS as ratio (e.g., 3.5x) and percentage (250%)
- Break-even ROAS (based on margins if provided)
- Comparison to platform benchmarks

3. 盈亏平衡分析

Break-Even CPA = Average Order Value × Profit Margin
Break-Even ROAS = 1 / Profit Margin

Inputs needed:
- Average order value (AOV) OR average deal value
- Profit margin (gross margin %)
- Current CPA or ROAS

Output:
- Maximum profitable CPA
- Minimum profitable ROAS
- Current headroom (how far above/below break-even)
- Recommendation: scale, maintain, or cut

4. 展示份额机会

Impression Share Lost (Budget) = opportunity from budget increase
Impression Share Lost (Rank) = opportunity from bid/quality improvement

Revenue Opportunity = Current Revenue × (1 / Current IS - 1)

Inputs needed:
- Current impression share %
- IS lost to budget %
- IS lost to rank %
- Current spend and conversions

Output:
- Estimated additional conversions from full IS
- Budget needed for full IS (estimated)
- Priority: budget increase vs quality improvement

5. 预算预测

Projected Spend = Daily Budget × Days in Period
Projected Conversions = Projected Spend / Historical CPA
Projected Revenue = Projected Conversions × AOV

Scaling scenarios:
- Conservative: +20% budget → estimated impact
- Moderate: +50% budget → estimated impact
- Aggressive: +100% budget → estimated impact (with diminishing returns caveat)

Inputs needed:
- Current daily budget
- Historical CPA (last 30 days)
- Forecast period
- AOV (if revenue projection needed)

Output:
- 3 scenarios with spend, conversions, revenue projections
- Diminishing returns warning for aggressive scaling
- 20% scaling rule reminder (never increase >20% at a time)

6. LTV:CAC 比率

CAC = Total Marketing Spend / New Customers Acquired
LTV = Average Revenue per Customer × Average Customer Lifespan
LTV:CAC Ratio = LTV / CAC

Inputs needed:
- Total marketing spend (all channels)
- New customers acquired
- Average revenue per customer (monthly or annual)
- Average customer lifespan (months)
- Optional: gross margin for unit economics

Output:
- LTV:CAC ratio with interpretation:
  - <1:1 = losing money on every customer
  - 1:1-2:1 = break-even to marginal
  - 3:1 = healthy (SaaS benchmark)
  - 5:1+ = may be under-investing in growth
- Payback period: months to recover CAC
- Recommendation based on ratio

7. MER（营销效率比）

MER = Total Revenue / Total Marketing Spend

Inputs needed:
- Total business revenue (period)
- Total marketing spend across ALL channels (same period)

Output:
- MER ratio (e.g., 5.0x)
- Interpretation:
  - E-commerce: 3-5x typical, 8x+ excellent
  - SaaS: 5-10x typical (higher margins)
  - Local service: 3-8x typical
- Comparison to business-type benchmark
- Note: MER captures blended efficiency including organic, brand, and retention

增量效果与高级衡量

对于评估跨渠道贡献的高级账户：

• Meta 增量归因（于 2025 年 4 月推出）：由 AI 驱动的留出组测试，用于衡量实际因果影响。评估预算是否超过每月 $5K。
• Google Meridian（2025 年）：用于衡量跨渠道增量效果的开源营销组合模型。
• 这些工具可补充 PPC 数学计算，衡量如果没有广告支出，本不会发生的情况。

对于需要检测小幅效果（5% 最小可检测效果，MDE）的大型账户，将 10% MDE 的样本量乘以约 4。

常用公式参考

指标	公式
CPA	支出 / 转化次数
ROAS	收入 / 支出
CTR	点击次数 / 展示次数 × 100
CVR	转化次数 / 点击次数 × 100
CPC	支出 / 点击次数
CPM	（支出 / 展示次数）× 1,000
CPL	支出 / 潜在客户数
盈亏平衡 CPA	AOV × 利润率%
盈亏平衡 ROAS	1 / 利润率%
LTV	ARPU × 平均生命周期
CAC	总营销支出 / 新客户数
MER	总收入 / 总营销支出
展示份额机会	收入 × (1/IS - 1)

输出格式

## PPC Financial Analysis

### [Calculator Name]

**Inputs:**
- [Listed inputs with values]

**Results:**
| Metric | Value | Benchmark | Status |
|--------|-------|-----------|--------|
| [Metric] | [Value] | [Benchmark] | PASS/WARNING/FAIL |

**Interpretation:**
[1-2 sentence analysis]

**Recommendation:**
[Actionable next step]

需要收集的数据

如果用户提供的数据不足，请询问：

• 平台和广告系列类型
• 分析时间段
• 支出和转化数据
• 收入数据（如果需要计算 ROAS/盈亏平衡）
• 利润率数据（如果需要计算盈亏平衡/LTV）
• 业务类型（用于基准比较）