Updated · Built and checked by the PlinzoTools team, formulas tested against published sources
Calculate monthly cash burn rate from starting cash, ending cash, and months elapsed.
$20,000.00
Burn rate measures how quickly a company is spending its cash reserves -- the key input for calculating runway.
Enter starting cash, ending cash, and the number of months between them. Monthly burn rate appears instantly.
Monthly Burn Rate = (Starting Cash - Ending Cash) / Months Elapsed
Suppose a hypothetical company had 500,000 in the bank six months ago and has 380,000 today. The drop is 120,000 over 6 months, so the monthly burn rate is 20,000. Those are the defaults in the calculator. If you feed that 20,000 into the Startup Runway Calculator with the current 380,000 balance, you get 19 months of runway at the present pace.
(500,000 - 380,000) / 6 = 20,000 per month
Because this tool measures the change in your cash balance, the result depends on which balance you enter. Use the same accounts at both points in time, for instance all operating bank accounts combined. Adding a savings account to one balance but not the other will make burn look larger or smaller than it is. Do not count receivables or inventory as cash; only money you can actually spend counts.
Since the calculation looks only at the cash change, revenue that arrived during the period is already reflected. This is net burn. If you raised money or received a large one-time payment in between, the balance change will understate the underlying spending. In that case, adjust your ending cash before entering it: subtract the financing you received, so the tool measures operating burn rather than the effect of new funds.
A short window is sensitive to timing. If a large annual insurance premium or a big customer payment happens to fall inside a one-month window, the calculated burn will swing. A longer window, such as three to six months, smooths this out but reacts slowly to recent changes such as a new hire or a lost client. Many founders calculate both a short and long window and watch whether they diverge. If the recent figure is meaningfully higher, spending is accelerating.
A burn rate is neither good nor bad on its own. What matters is how it relates to your cash and your plan. A high burn can be reasonable if it is buying growth you can measure, and a low burn can be a problem if the business is not progressing. Compare burn against your milestones: what will you have achieved by the time the cash runs out, and will that position let you raise more money or become self-sustaining?
This estimate is for internal planning. For formal reporting or lender submissions, rely on your accounting records and professional advice.
Gross burn is total cash spent; net burn subtracts any revenue earned in the period. This calculator computes net burn (based on actual cash balance change), the more common runway-planning figure.
It subtracts your ending cash from your starting cash and divides by the number of months in between: (starting cash - ending cash) / months. The result is the average net cash you lost per month.
A negative result means your cash grew over the period, so the business generated more cash than it spent. It is not an error; it simply means there was no net burn.
Net burn. Because it compares the cash balance at two dates, money coming in from customers is already offset against money going out. Gross burn (total spending regardless of income) needs your expense figures instead.
The result is an average per month, so a period of 6 months with a 60,000 drop gives 10,000 per month. Use whole or fractional months that match the two balances you entered, and enter more than zero months.
Divide your current cash balance by the monthly burn. The Startup Runway Calculator on this site does exactly that division for you.
Reference: Consumer Financial Protection Bureau