Custom columns are formulas that live inside Google Ads: they appear in the tables like any other metric, and they can be used in filters, in column sets and in automated rules. They let you see your business CPA or POAS without leaving for a spreadsheet. This tutorial creates them and gives you twelve ready to copy.
Step 1 · Create a column
In any table → Columns → Custom columns → +:
- Name and description.
- Formula: type
{or use the picker to insert metrics (Cost, Conversions, Conv. value, Clicks…), operators (+ − × ÷), functions (if,min,max,round…) and constants. - Filter a metric by conversion action: when you insert Conversions, "Filter by" → Conversion action = "Qualified lead": the metric then counts that action only. This is the most useful feature.
- Format: number, percentage, currency, text.
- Save. The column becomes available in every table at that level (campaign, ad group, keyword…).
Twelve columns to copy
| Column | Formula (interface pseudocode) | What for |
|---|---|---|
| Qualified CPA | Cost ÷ Conversions[action = Qualified lead] |
The cost per real contact |
| Sale CPA | Cost ÷ Conversions[action = Sale] |
Cost per customer |
| Qualification rate | Conversions[Qualified lead] ÷ Conversions[Form] |
Lead quality by campaign |
| POAS | (Conv. value[Purchase] × 0.35 − Cost) ÷ Cost (0.35 = average margin) |
Profit per euro; or better still, with value = margin |
| Net ROAS | Conv. value[Purchase] ÷ 1.21 ÷ Cost |
ROAS excluding VAT if the value includes it |
| % of L1 | Conv. value[L1 actions] ÷ Value of all conv. |
The 50% rule |
| Cost per call | Cost ÷ (Conversions[Call from ad] + Conversions[Call from web]) |
Call-driven businesses |
| Total lost IS | Search lost IS (budget) + Search lost IS (rank) |
The share you aren't buying |
| CPA deviation vs target | (Cost ÷ Conversions) ÷ 45 − 1 (45 = the target) |
A compliance traffic light |
| Real conversion rate | Conversions[business primaries] ÷ Clicks |
Without L1 |
| Cost per useful lead | Cost ÷ (Conversions[Qualified] + Conversions[Sale]) |
The lead generation summary |
| Average daily spend | Cost ÷ Days in the period (a constant per range) |
Pace |
The constants (margin, target, VAT) are written into the formula; they have to be reviewed when they change. For different targets per campaign, the column works as an approximation or you create several.
Step 2 · Use them
- Filters: "POAS < 0" → the list of campaigns making a loss; "CPA deviation > 0.15" → the ones missing target.
- Column sets (module 7 of the Basic level): a "Business" set with qualified CPA, POAS, % L1 and deviation.
- Automated alert rules: "if POAS < 0 for 7 days → email".
- Report editor and Looker: custom columns are available as metrics.
- Sorting the tables by them.
Functions and details
if(condition, a, b): text traffic lights ("🔴"/"🟢") with text format.- Divisions by zero: wrap them with
if(Conversions > 0, …, 0). - Metrics filtered by action only exist for conversion metrics (Conversions, Value, All conv.).
- Columns are per account; in a manager account you have to recreate them (or use manager account templates).
- They have no history of their own: they are formulas over the metrics of the range you have chosen.
Common mistakes
- Forgetting the filter by action: a "qualified CPA" that is really the CPA of everything.
- Out-of-date constants (last year's margin).
- Accidentally mixing Conversions (primary) with All conversions in one formula.
- Percentage format on a ratio that is already a percentage.
💡 Ninja trick: custom columns are the manual version of the SBNS judge: "CPA deviation vs target" with one constant per account. They are for looking; the judge is for acting, with a target per campaign, reference conversions and windows. If you build the twelve columns and look at them every Monday, you have 70% of what the script decides every night — the difference is that it never misses a Monday.
What you should remember
- Columns with formulas over metrics, filtered by conversion action,
with constants and
if. - Twelve useful ones: qualified CPA, sale CPA, POAS, net ROAS, % L1, cost per call, total lost IS, deviation vs target…
- Use them in filters, column sets, alert rules, reports and Looker.
- Review the constants; watch out for Conversions vs All conversions.
End of Module 12. Module 13, Practical tutorials III — operations, covers experiments, Google Ads Editor, rules, scheduling, exclusions, local campaigns and the audit of an inherited account.