Available Metrics for Rule Conditions
Last updated: April 18, 2026
Wevion's Rules Engine gives you access to 20 performance metrics that you can use as conditions in your automation rules. This article explains every metric: what it measures, how Wevion calculates it (for derived metrics), and practical guidance on when to use it.
Understanding these metrics is essential for building effective rules. Choosing the wrong metric — or misunderstanding how one is calculated — can lead to rules that fire too aggressively or not at all.
Prerequisites
- Familiarity with Wevion rules concepts (Introduction to Rules — Automate Your Ad Management).
- Basic understanding of Meta Ads performance metrics.
How Metrics Are Sourced
Wevion collects raw performance data from Meta's Insights API every 15 minutes. Some metrics come directly from Meta (like spend, impressions, and clicks), while others are derived — calculated by Wevion from the raw data. Derived metrics are marked with a formula in the tables below.
When a derived metric involves division, Wevion handles the zero-denominator case gracefully: if the denominator is zero, the metric evaluates to zero (not infinity or an error). This matters for rules — a campaign with zero clicks will report a CTR of 0%, not cause an evaluation failure.
Spending Metrics
These metrics track how your budget is being consumed.
| Metric | What It Measures | Calculation | When to Use It |
|---|---|---|---|
| Spend | Total amount spent in the selected timeframe | Direct from Meta | Budget protection. The most common metric for "stop loss" rules. Example: pause when spend > $100 with no results. |
| Budget Spent % | Percentage of daily budget already consumed | (Spend / Daily Budget) x 100 | Pacing control. Detect campaigns burning through budget too quickly or too slowly. Example: alert when budget_spent_pct > 80% before noon. |
Practical Notes on Spending Metrics
Spend is the foundation of most protection rules. It tells you exactly how much money has left your account. Combine it with conversion metrics to create spend-efficiency rules.
Budget Spent % is uniquely powerful for pacing. A campaign that has spent 90% of its daily budget by 2 PM is spending too fast — Meta will either exhaust the budget early or drastically slow delivery. A rule that decreases budget or sends an alert at 80% can help you catch pacing issues before they become problems.
Engagement Metrics
These metrics measure how people interact with your ads.
| Metric | What It Measures | Calculation | When to Use It |
|---|---|---|---|
| Impressions | Number of times your ad was displayed | Direct from Meta | Volume-based rules. Useful for ensuring a campaign has enough data before other rules evaluate it. |
| Clicks | Number of clicks on your ad | Direct from Meta | Engagement monitoring. Rarely used alone — more useful in combination with spend or conversions. |
| Reach | Number of unique people who saw your ad | Direct from Meta | Audience saturation detection. Compare reach to impressions to understand frequency. |
| Frequency | Average number of times each person saw your ad | Impressions / Reach | Ad fatigue detection. High frequency means the same people are seeing your ad repeatedly. Example: alert when frequency > 3 over last 7 days. |
| CTR | Click-through rate — percentage of impressions that resulted in a click | (Clicks / Impressions) x 100 | Creative quality signal. Low CTR suggests the ad is not resonating. Example: pause ads with CTR < 0.5% after 5,000 impressions. |
Practical Notes on Engagement Metrics
Frequency is one of the most underused metrics in automation. When frequency climbs above 2.5-3.0 over a 7-day window, ad fatigue typically sets in: CTR drops, costs rise, and audience sentiment turns negative. A rule that alerts you at frequency > 3 gives you time to refresh creatives before performance degrades.
CTR is best used at the ad level to identify weak creatives. Be careful with short timeframes — a low CTR over "today" might just mean your ad has had few impressions so far. Combine CTR conditions with an impressions threshold (e.g., CTR < 1% AND impressions > 2,000) to avoid premature judgments.
Conversion Metrics
These metrics track the results that matter most — actions taken by users after clicking your ads.
| Metric | What It Measures | Calculation | When to Use It |
|---|---|---|---|
| Purchases | Number of purchase conversions | Direct from Meta | The primary result metric for e-commerce. Use in combination with spend for ROI-based rules. |
| Purchase Value | Total revenue from purchase conversions | Direct from Meta | Revenue tracking. Combine with spend to calculate profitability. |
| Leads | Number of lead conversions | Direct from Meta | Lead generation campaigns. Use like purchases, but for lead-focused objectives. |
| Add to Cart | Number of add-to-cart events | Direct from Meta | Mid-funnel signal. Useful for detecting campaigns that attract interest but fail to convert to purchase. |
| Conversions | Total number of conversion events (all types) | Direct from Meta | General conversion tracking when you are not focused on a specific conversion type. |
Practical Notes on Conversion Metrics
Purchases = 0 is the most common trigger condition in spend protection rules. "If spend > $X and purchases = 0, pause" is the rule every media buyer should have active from day one.
Add to Cart is a valuable leading indicator. A campaign with high add-to-cart but low purchases suggests a checkout issue, pricing problem, or audience mismatch — not necessarily a bad ad. Consider using notify_only with add-to-cart conditions rather than automatic pausing.
Efficiency Metrics
These derived metrics help you evaluate cost-effectiveness and return on investment.
| Metric | What It Measures | Calculation | When to Use It |
|---|---|---|---|
| ROAS | Return on ad spend — revenue generated per dollar spent | Purchase Value / Spend | The gold standard for e-commerce profitability. Example: scale when ROAS > 3x, pause when ROAS < 1x. |
| CPA | Cost per acquisition — how much you pay for each purchase | Spend / Purchases | Cost control. Alternative to ROAS when you think in terms of cost per result rather than return multiples. |
| CPL | Cost per lead — how much you pay for each lead | Spend / Leads | Lead generation cost control. The lead-gen equivalent of CPA. |
| CPC | Cost per click — how much you pay for each click | Spend / Clicks | Traffic cost monitoring. High CPC may indicate audience saturation or competitive auction pressure. |
| CPM | Cost per mille — cost per 1,000 impressions | (Spend / Impressions) x 1,000 | Market cost monitoring. Rising CPM often signals increased competition or audience exhaustion. |
| Profit | Net profit after ad spend | Purchase Value - Spend | Absolute profitability. Unlike ROAS (which is a ratio), profit tells you the actual dollar amount gained or lost. |
| Conversion Rate | Percentage of clicks that resulted in a purchase | (Purchases / Clicks) x 100 | Landing page and funnel quality signal. Low conversion rate with high CTR suggests the ad is good but the landing page is not converting. |
| AOV | Average order value — average revenue per purchase | Purchase Value / Purchases | Basket size monitoring. Useful for detecting if discount codes or audience changes are lowering order values. |
Practical Notes on Efficiency Metrics
ROAS vs. Profit: ROAS tells you the ratio, profit tells you the amount. A campaign with 5x ROAS but $10 in spend generated $40 profit. A campaign with 2x ROAS and $1,000 in spend generated $1,000 profit. Both metrics have their place — ROAS for efficiency assessment, profit for absolute impact.
CPA is particularly useful when you know your breakeven cost per acquisition. If your product margins allow a maximum $25 CPA, a simple rule like "pause when CPA > $30 over last 3 days" protects your profitability without requiring you to think in ROAS terms.
Conversion Rate is an excellent diagnostic metric. If conversion rate drops suddenly while CTR stays stable, the problem is likely on your website, not in your ads. Use notify_only rules to catch these shifts early.
Choosing the Right Metric for Your Rule
Here is a quick decision framework:
"I want to stop wasting money" — Use Spend combined with Purchases (or Conversions). This is your bread-and-butter protection rule.
"I want to scale what is working" — Use ROAS or Profit over a longer timeframe (last 7 days or last 14 days) to identify consistent winners.
"I want to catch fatigue early" — Use Frequency over last 7 days, or monitor CTR trends with notify_only rules.
"I want to control costs" — Use CPA, CPL, or CPC depending on your campaign objective.
"I want to monitor pacing" — Use Budget Spent % to detect campaigns burning through budget too fast or too slow.
"I want to find funnel problems" — Use Conversion Rate combined with CTR. High CTR + low conversion rate = landing page issue.
Important Considerations
Minimum Data Thresholds
Derived metrics like ROAS, CPA, and CTR can be misleading with small sample sizes. A campaign with 1 purchase from $5 in spend shows a fantastic CPA of $5 — but that might just be luck. Always pair efficiency metrics with a volume condition:
- ROAS condition + Spend > $50 (or your minimum confidence threshold)
- CTR condition + Impressions > 2,000
- CPA condition + Purchases > 3
Timeframe Sensitivity
The same metric can tell very different stories depending on the timeframe. A campaign might have a 5x ROAS over the last 7 days but only 0.8x ROAS today. Choose your timeframe based on what question you are trying to answer.
Rule Conditions — Operators and Time Ranges
FAQ
Q: Are all 20 metrics available for all entity levels? A: Most metrics are available at campaign, ad set, and ad level. Budget-related metrics (daily_budget, lifetime_budget, bid_amount) depend on where the budget is set — bid_amount is only available at the ad set level.
Q: What happens if a metric has no data (e.g., zero impressions)? A: Derived metrics with a zero denominator return 0. For example, CTR with zero impressions = 0%, CPA with zero purchases = 0. This means conditions like "CPA < $10" would match entities with no purchases — always pair efficiency metrics with a volume condition.
Q: Can I use multiple metrics in the same rule? A: Yes. Each condition uses one metric, but you can add multiple conditions with AND/OR logic to combine metrics.
Rule Conditions — Operators and Time Ranges