How to calculate cost per click in SQL

What you need

Cost per click (CPC) is the average price you pay each time someone clicks your ad: ad spend divided by the number of clicks. You need these columns, here from the sample file monthly.csv:

• marketing_spend: marketing spend
• ad_clicks: ad clicks

CREATE TABLE monthly (
  month TEXT,          -- 'YYYY-MM'
  marketing_spend INTEGER,
  ad_clicks INTEGER
);

Step by step

1. Load monthly.csv into a table called monthly. The table only needs the month column and the columns below.
2. Run the first query to get one row per month.
3. Run the whole-period query. It adds up each column first and divides once; averaging the monthly results gives a different, usually wrong, answer.

The queries

SELECT
  month,
  ROUND(1.0 * marketing_spend / NULLIF(ad_clicks, 0), 2) AS cpc
FROM monthly
ORDER BY month;

SELECT ROUND(1.0 * SUM(marketing_spend) / NULLIF(SUM(ad_clicks), 0), 2) AS cpc
FROM monthly;

What you should get

Run against the sample data, the code above returns these values:

₹6,70,000 ÷ 67,810 = ₹9.88

Notes for SQL

• Integer columns divide as integers in PostgreSQL, SQLite and SQL Server, so 3 / 4 gives 0. Multiplying by 1.0 (or 100.0) first makes the division decimal.
• NULLIF(x, 0) turns a zero denominator into NULL, so the query returns NULL for that row instead of failing with a division-by-zero error.
• Tested on SQLite and DuckDB. SUM, NULLIF and ROUND work the same in PostgreSQL, MySQL and BigQuery; SQL Server uses TOP instead of LIMIT where a query has one.

Where cost per click misleads

• Here all marketing spend is divided by ad clicks, which overstates CPC if some spend is not on click-based ads. Use only click-based spend when you can.
• Platforms count clicks differently (link clicks, all clicks). Compare within one platform.
• Cheap clicks from poor placements can lower CPC and raise cost per order.

The full explanation, with a calculator, is on the Cost per click (CPC) page.

Same metric, other tools

• Cost per click in Excel and Google Sheets
• Cost per click in Python (pandas)

Related metrics in SQL

• How to calculate click-through rate in SQL
• How to calculate cost per thousand impressions in SQL
• How to calculate conversion rate in SQL
• How to calculate revenue per session in SQL

Learn more about SQL

• Python and SQL for data analysis, side by side — 3 min read
• How to find out what changed in your sales data — 2 min read

About the data on this page

The figures come from a small made-up dataset, printed above in full so you can check every number by hand. Download it as monthly.csv. The results are computed from those rows when the page is built, and the Excel formulas, SQL and Python on these pages are run against the same rows before publishing, so the code and the answers agree.

To get these numbers from your own data without writing formulas, try AnalyzeIt: ask in plain words and it shows the working behind every figure.