How do I calculate burn rate and runway?
"How many months of cash do we have?" gets asked at every board meeting, and the honest answer is usually a bank balance divided by a number someone pulled from a January budget. Gross burn, net burn, trailing three months or twelve — the definitions drift, and the spreadsheet drifts with them. The demo below computes the whole thing from a cash activity export: monthly net burn, the trailing 3-month average, and runway in months from the closing balance — with the SQL that does it.
The cash_activity.csv sample (period…) is registered as a DuckDB table in your browser — the exact engine workspaces use. SQL is always shown.
Running on the sample cash_activity.csv — the question is editable, and the Your own CSV tab registers your file in your browser instead.
Sample datacash_activity.csv
How to calculate burn rate and runway — without the manual grind
Net burn, not gross
Gross burn (cash out) ignores the revenue coming back in; the number that predicts the zero-cash date is net burn: cash out − cash in per month. The generated SQL encodes that definition once, visibly.
Runway = balance ÷ trailing average
Dividing by one month's burn makes runway whipsaw with every payroll cycle. The demo divides the cash balance by the trailing 3-month average net burn — and shows runway per month, so the trend (widening or narrowing) is visible, not just the snapshot.
Re-run it every month, identically
In a workspace the query saves as a re-runnable artifact with a share link. Each month's export re-computes the table — the runway conversation starts from the same definition every time.
Common questions
What is the burn rate and runway formula?
Net burn = cash out − cash in for the period. Runway = cash balance ÷ average net burn (the demo uses a trailing 3-month average; swap the window by editing the SQL). Gross burn (cash out only) is the same template with cash_in removed.
What export shape does it expect?
Any monthly cash activity with in/out columns — cash_in/cash_out, receipts/disbursements, inflows/outflows — plus optionally a cash balance column. The matcher handles the naming variants; the balance column is what turns burn into runway.
Does my file get uploaded anywhere?
No. The demo registers your file as a DuckDB-WASM virtual table inside your browser tab. It never leaves your machine — which is the same architecture workspaces use, by design, for finance data.
Run this on your own export, every month
Free workspace: 10 questions/day, files up to 10 MB. Pro $15/mo ($99/yr) for 100 MB. Your files never leave your browser.
client-side by design SQL always shown
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