People type this into search every day: cash runway calculator.
The usual answer is cash divided by monthly burn. That division is the flat case, and it still rounds the last month off. A growing payroll, a client who pays late, and a month that only spends part of the burn all move the count.
This page is a planning model. It is not a forecast, and it is not advice about raising money or cutting a job.
One month at a time, until the balance gives out
The cash runway calculator starts with the cash you have. Each month it adds cash revenue and subtracts that month’s spending. Then it raises spending by the growth rate you typed, and it counts the month. It stops when the balance is no longer above zero, or at 240 months, whichever comes first.
Revenue stays constant. No new financing and no one-off cash flows. Those are the tool’s assumptions.
Net burn on the card is this month’s spending minus this month’s revenue. It can be negative. Negative burn means cash is growing.
Fig 1
Cash in, spend out, then grow the spend
Revenue stays flat. Spending can rise every month.
Each month adds revenue and subtracts spend. Spend then grows. The count stops when cash is no longer above zero.
The SBA’s Manage your finances page treats the balance sheet as the snapshot you project cash flow from, and it separates the cash method from accrual. The cash method records a sale when the payment arrives. A sent invoice is not monthly cash revenue until it clears. The late invoice fee post is the cost of that wait. The emergency fund post is the household version of the same question.
The detail line labeled “Spend in final month” is the spend after the last counted month raises it. On the default run, month 9 is charged $65,336.57. The card then prints $66,316.62, which is that charge times 1.015. The cash path below uses the amount actually charged.
Example 1: the published $240,000, with spend growing 1.5%
Here are the calculator defaults:
- cash available: $240,000
- monthly cash revenue: $32,000
- monthly cash spending: $58,000
- monthly spend growth: 1.5%
Current net burn: 58000 − 32000 = $26,000.00
Runway: 9 months
Cash after 6 months: $70,686.05
Spend in final month, the raised figure: $66,316.62
Calculator result
Cash runway
- Cash available
- $240,000.00
- Monthly cash revenue
- $32,000.00
- Monthly cash spending
- $58,000.00
- Monthly spend growth
- 1.5%
9 months
estimated cash runway
- Current net burn
- $26,000.00
- Cash after 6 months
- $70,686.05
- Spend in final month
- $66,316.62
The month-by-month path, with full-precision balances:
| Month | Spend charged | Balance after |
|---|---|---|
| 1 | $58,000.00 | $214,000.00 |
| 2 | $58,870.00 | $187,130.00 |
| 3 | $59,753.05 | $159,376.95 |
| 4 | $60,649.35 | $130,727.60 |
| 5 | $61,559.09 | $101,168.52 |
| 6 | $62,482.47 | $70,686.05 |
| 7 | $63,419.71 | $39,266.34 |
| 8 | $64,371.00 | $6,895.33 |
| 9 | $65,336.57 | -$26,441.24 |
Month 6 matches the card. Month 8 leaves $6,895.33, which cannot cover month 9’s $65,336.57 charge, so the balance crosses zero during month 9 and the tool counts 9 months. The model charges a whole month at once. It does not prorate the last $6,895.33 into a fraction of a month.
Fig 2 · 1/3
Default cash, month by month
$240,000 in the bank. Spend starts at $58,000 and grows 1.5%.
Start
$240,000
Month 6
Month 6 next
$70,686.05
Month 9
Runway next
9 months
Cash starts at $240,000. Net burn is $26,000.
After month 6 the balance is $70,686.05.
Month 9 is the month the balance crosses zero.
Example 2: the same business with spend growth turned off
Keep $240,000, $32,000 of revenue, and $58,000 of spending. Set growth to 0%.
Net burn stays $26,000.00 every month.
Runway: 10 months
Cash after 6 months: 240000 − 26000 × 6 = $84,000.00
Spend in final month: $58,000.00
After month 9 the balance is 240000 − 26000 × 9 = $6,000.00. Month 10 charges another $58,000 and the balance goes to -$20,000.00. The tool counts that 10th month.
Dividing 240000 ÷ 26000 gives 9.23 months. That is the number people quote. It describes a partial month the model never bills. The calculator’s answer at 0% growth is 10 whole months. At 1.5% growth, Example 1, the same starting burn lasts 9 months, and the 6-month balance is $70,686.05 instead of $84,000. Growth costs a month and $13,313.95 of the month-6 cash (84000 − 70686.05).
Fig 3 · 1/2
Cash with growth, and without it
Both lines start at $240,000, $32,000 revenue, $58,000 spend
Cash left
- 1.5% growth
- No growth
| Point | 1.5% growth | No growth |
|---|---|---|
| Start | $240k | $240k |
| Month 2 | $187k | $188k |
| Month 4 | $131k | $136k |
| Month 6 | $71k | $84k |
| Month 8 | $6.9k | $32k |
With 1.5% spend growth, month 8 still has $6,895.33.
With flat spend, month 8 still has $32,000. The runway is 10 months.
Example 3: a freelancer with $18,000 in the bank
- cash: $18,000
- monthly revenue: $4,000
- monthly spending: $6,500
- growth: 0%
Net burn: $2,500.00
Runway: 8 months
Cash after 6 months: 18000 − 2500 × 6 = $3,000.00
Spend in final month: $6,500.00
Calculator result
Cash runway
- Cash available
- $18,000.00
- Monthly cash revenue
- $4,000.00
- Monthly cash spending
- $6,500.00
- Monthly spend growth
- 0%
8 months
estimated cash runway
- Current net burn
- $2,500.00
- Cash after 6 months
- $3,000.00
- Spend in final month
- $6,500.00
18000 ÷ 2500 = 7.2 months. After month 7 the cash left is 18000 − 2500 × 7 = $500. Month 8 spends $6,500 and the balance goes negative, so the tool reports 8 months. The $500 does not buy a fifth of a month inside this model.
Example 4: what if revenue drops to zero
Back to the default cash and the default $58,000 spend, growing at 1.5%. Monthly revenue becomes $0. A client stops paying, or you stop counting invoices as cash.
Net burn: $58,000.00
Runway: 5 months
Cash after 6 months: $0.00
Spend in final month: $62,482.47
The 6-month line prints $0 because the balance is already below zero by then, and the tool floors that detail at zero. The path:
| Month | Spend charged | Balance after |
|---|---|---|
| 1 | $58,000.00 | $182,000.00 |
| 2 | $58,870.00 | $123,130.00 |
| 3 | $59,753.05 | $63,376.95 |
| 4 | $60,649.35 | $2,727.60 |
| 5 | $61,559.09 | -$58,831.48 |
240000 ÷ 58000 = 4.14 on a flat burn. Even with growth at 0%, four months would leave 240000 − 58000 × 4 = $8,000, and month 5 would still be required. The tool’s 5 months is the whole-month count. Losing the $32,000 of revenue takes the default 9-month runway down to 5.
Example 5: what if spending drops by $8,000
Keep $240,000, $32,000 of revenue, and 1.5% growth. Cut starting spend from $58,000 to $50,000.
Net burn: 50000 − 32000 = $18,000.00
Runway: 11 months
Cash after 6 months: $120,522.45
Spend in final month: $58,897.45
The flat division says 240000 ÷ 18000 = 13.33 months. Growth pulls the model back to 11. Ignoring the 1.5% rise is a two-month miss on this cut. Compared with Example 1, $8,000 less starting spend buys 11 − 9 = 2 months, and it leaves 120522.45 − 70686.05 = $49,836.40 more cash at month 6.
Example 6: break-even today, with spend still growing
Set revenue equal to the starting spend. Cash stays $240,000. Growth stays 1.5%. Both revenue and starting spend are $58,000.
Current net burn: $0.00
Runway: 23 months
Cash after 6 months: $226,686.05
Spend in final month: $81,685.87
Calculator result
Cash runway
- Cash available
- $240,000.00
- Monthly cash revenue
- $58,000.00
- Monthly cash spending
- $58,000.00
- Monthly spend growth
- 1.5%
23 months
estimated cash runway
- Current net burn
- $0.00
- Cash after 6 months
- $226,686.05
- Spend in final month
- $81,685.87
Month 1 changes nothing, because revenue and spend match. Month 2 spends $58,870 against $58,000 of revenue. The gap widens every month after that. A business that covers its bills this month, with spending planned to rise and revenue planned to stay flat, runs out of the $240,000 during month 23. The zero on the burn line is the opening month only.
Turn the growth off as well and the balance never falls. The tool stops at its 240 month cap. Net burn stays $0.00. Cash after 6 months stays $240,000.00. Spend in the final counted month stays $58,000.00. 240 is the ceiling in the code. The loop stops there.
Example 7: cash is already growing
- cash: $40,000
- monthly revenue: $12,000
- monthly spending: $9,000
- growth: 0%
Net burn: 9000 − 12000 = -$3,000.00
Runway: 240 months
Cash after 6 months: 40000 + 3000 × 6 = $58,000.00
Spend in final month: $9,000.00
The balance rises by $3,000 a month, so the loop never sees a balance at or below zero. It hits the same 240-month cap as the flat break-even case. Read 240 here as “the model does not run out.” If you expect spending to rise, put that rise in the growth field. Example 6 is what a 1.5% rise does to a month that currently breaks even.
Example 8: a thin gap, and a faster rise
Two shorter variations on the same idea.
Thin gap, no growth:
- cash: $8,000
- revenue: $6,000
- spending: $7,200
- growth: 0%
Net burn: $1,200.00
Runway: 7 months
Cash after 6 months: 8000 − 1200 × 6 = $800.00
8000 ÷ 1200 = 6.67. The $800 left after month 6 still needs a 7th month in this model.
Faster rise on the default business. Keep $240,000, $32,000, and $58,000. Set growth to 5% instead of 1.5%.
Runway: 7 months
Cash after 6 months: $37,489.06
Spend in final month: $81,611.82
The opening burn is still $26,000. The 5% rise takes two months off Example 1 (9 down to 7) and leaves 70686.05 − 37489.06 = $33,196.99 less cash at month 6.
Fig 4 · 1/4
Months until cash crosses zero
Whole months. The 240-month cap is a separate case.
- Months
| Category | Months |
|---|---|
| Default | 9 |
| Flat | 10 |
| No revenue | 5 |
| Spend cut | 11 |
The default, with 1.5% spend growth, lasts 9 months.
Flat spend lasts 10. Zero revenue lasts 5. A $50,000 starting spend lasts 11.
Fig 5 · 1/3
Cash still there after six months
The three cases that still have cash at month 6
Cash after 6 months
Default
$70,686.05
Flat spend
$84,000
Spend cut
$120,522.45
The default still holds $70,686.05.
Flat spend holds $84,000. The spend cut holds $120,522.45. Zero revenue is already at $0, so it is off this chart.
The eight runs next to each other
| Example | Cash | Revenue | Spend | Growth | Burn | Months | Cash at month 6 |
|---|---|---|---|---|---|---|---|
| 1. Defaults | $240,000 | $32,000 | $58,000 | 1.5% | $26,000 | 9 | $70,686.05 |
| 2. Growth off | $240,000 | $32,000 | $58,000 | 0% | $26,000 | 10 | $84,000.00 |
| 3. Freelancer | $18,000 | $4,000 | $6,500 | 0% | $2,500 | 8 | $3,000.00 |
| 4. Revenue at zero | $240,000 | $0 | $58,000 | 1.5% | $58,000 | 5 | $0.00 |
| 5. Spend cut | $240,000 | $32,000 | $50,000 | 1.5% | $18,000 | 11 | $120,522.45 |
| 6. Break-even, growing | $240,000 | $58,000 | $58,000 | 1.5% | $0 | 23 | $226,686.05 |
| 7. Cash growing | $40,000 | $12,000 | $9,000 | 0% | -$3,000 | 240 | $58,000.00 |
| 8. Thin gap | $8,000 | $6,000 | $7,200 | 0% | $1,200 | 7 | $800.00 |
| 8. Growth at 5% | $240,000 | $32,000 | $58,000 | 5% | $26,000 | 7 | $37,489.06 |
Open the cash runway calculator with cash that is already in the account, revenue you collect in a normal month, and spending you actually pay. Leave growth at 0% when you want the flat burn. Put a rise in only when you expect spending to change. Unpaid invoices stay out of the revenue box until they clear. The monthly budget planner is the household list behind a personal burn rate. The meeting cost post is one line that can sit inside monthly spending.