I've worked with 50+ SaaS founders who thought they had 6 months of runway but had 3. The problem? They were using mental math instead of a real model.
Here's the simple 3-tab model I built in Google Sheets that fixes this:
Tab 1: Dashboard — starting cash, net burn, runway months, cash-zero date. Color alerts: green (>12mo), yellow (6-12mo), red (<6mo). You see it in 3 seconds.
Tab 2: Monthly Log — rows for each month, columns for revenue, COGS, salaries, marketing, hosting, other. Formulas automatically calculate net burn.
Tab 3: Scenarios — try different MRR growth rates (10%, 5%, 0%) and expense growth rates. See how runway changes.
The dashboard formula for runway is simple:
=ROUND(B5/((B5-B6)/MONTHS)) where B5 is starting cash, B6 is ending cash, MONTHS is the period.
I packaged this into a ready-to-use Google Sheets template — you can grab it here: [link to Gumroad product - SaaS Burn Rate & Runway Calculator]
Pro tip: The best time to check your runway is BEFORE you need to fundraise. Set a recurring weekly calendar reminder to update the template (takes 3 minutes).
Tags: #googlesheets #saas #startup #finance #excel
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