🔥 Burn Rate & Cash Runway Calculator
A burn rate calculator that computes net and gross monthly burn from your cash balance history, and how many months of runway remain.
What Burn Rate & Cash Runway Calculator Does
Burn rate and runway are really one calculation viewed from two directions: burn rate asks "how fast is cash declining," and runway asks "given that speed, how long until it hits zero." Startups and early-stage businesses track both because they answer the single most consequential planning question a pre-profitability company faces — how much time is actually left before the next fundraise or a path to breakeven has to be real.
The net-versus-gross distinction matters because a business with meaningful revenue can have a deceptively small net burn while still spending (and needing to raise) far more in absolute terms — net burn is what determines runway, but gross burn is closer to what a lender or investor means by "how much does this business actually cost to run."
How to Use Burn Rate & Cash Runway Calculator
- Enter your current cash balance and your cash at the start and end of a recent period
- Enter how many months that period covered, and optional monthly revenue
- Read your net burn, gross burn, and remaining cash runway
Formula Used by Burn Rate & Cash Runway Calculator
Net burn rate and runway
Net burn = (starting cash − ending cash) ÷ months · Runway (months) = current cash balance ÷ net burn
Worked example
$550,000 cash at start of month, $500,000 at end, current balance $500,000
- Net burn: (550,000 − 500,000) ÷ 1 = $50,000/month
- Runway: 500,000 ÷ 50,000
Result: 10.0 months of runway at the current burn rate
How to Read Your Result
Runway is a snapshot, not a forecast
It assumes the exact same burn rate continues every month going forward, which real businesses rarely do — hiring plans, revenue growth, and one-time expenses all move burn rate over time. Recalculate runway regularly rather than treating one calculation as a fixed deadline.
A common planning mistake is measuring burn over too short a window
A single month with an unusual one-time expense (a big software renewal, a legal bill) can make burn rate look far worse than the underlying trend — averaging over 3 months smooths out this kind of noise and gives a more representative number.
Limitations & Accuracy Notes
- This is a backward-looking calculation based on a historical period — it does not forecast future changes in spending or revenue.
- Does not distinguish between essential operating burn and one-time or discretionary spending, which can matter a lot for planning purposes.
- Assumes the burn rate is roughly linear within the measured period; a business with highly irregular cash flow (large lumpy payments) will see this estimate diverge from actual month-to-month experience.