How to calculate Average Deal Size

Formula

Average deal size = total value of won deals ÷ number of won deals

SQL query

This example assumes: deals(id, stage, amount, closed_at). It is written in PostgreSQL syntax; date functions differ slightly in MySQL, BigQuery and SQLite, and your column names will differ from these.

SELECT DATE_TRUNC('quarter', closed_at) AS quarter,
       COUNT(*)                                AS deals_won,
       SUM(amount)                             AS total_won,
       SUM(amount) / NULLIF(COUNT(*), 0)       AS avg_deal_size
FROM deals
WHERE stage = 'won'
GROUP BY 1
ORDER BY 1;

Common mistakes that make Average Deal Size wrong

• One very large deal can double the average; show the median next to it.
• Mixing one-off and recurring deals in one amount column compares unlike things.
• Using list price instead of the signed amount ignores discounts.

Ask for Average Deal Size in plain English

Instead of writing the query yourself, you can type the question. SchemaChat turns it into SQL against your connected database or uploaded file, runs it, and shows the SQL and the figures it used so you can check the answer before you share it. It does not replace your judgement about the definition: check that the query matches the formula your business uses.

• What was the average deal size by quarter?
• Show average and median deal size for won deals this year.