How to calculate Cash Runway

Formula

Runway (months) = cash balance ÷ monthly net burn

SQL query

This example assumes: cash_balance(as_of, balance), cash_flows(day, amount). It is written in PostgreSQL syntax; date functions differ slightly in MySQL, BigQuery and SQLite, and your column names will differ from these.

WITH burn AS (
  SELECT -SUM(amount) / 3.0 AS avg_monthly_burn
  FROM cash_flows
  WHERE day >= CURRENT_DATE - INTERVAL '3 months' AND day < CURRENT_DATE
), bal AS (
  SELECT balance FROM cash_balance ORDER BY as_of DESC LIMIT 1
)
SELECT bal.balance / NULLIF(burn.avg_monthly_burn, 0) AS runway_months
FROM bal, burn
WHERE burn.avg_monthly_burn > 0;

Common mistakes that make Cash Runway wrong

• If burn is zero or negative, runway is not meaningful; the query returns no row on purpose.
• Known upcoming costs and revenue changes make the simple formula wrong.
• Include only freely available cash, not restricted or committed funds.

Ask for Cash Runway 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.

• How many months of runway do we have at our trailing average burn?
• What would runway be if burn rose 20%?