Runway Calculator
Convert cash and burn into months of survival, model burn that grows rather than holds flat, and size the funding gap before it becomes urgent.
Runway Calculator
Results recalculate instantly on every keystroke. Nothing you type is transmitted.
What this result does not account for
- A projection from current burn, not a forecast of actual future cash movements.
- Ignores working-capital swings unless they are already reflected in the burn figure.
- Treats undrawn facilities as unavailable, which is conservative but not always accurate.
In short: $180,000 of cash against a $90,000 monthly burn is 2.00 months of runway. Releasing the $287,584.72 trapped in the cash cycle would extend that to 5.20 months — without raising a cent of new capital.
Formula
The simple division assumes burn holds flat. Where burn grows the engine iterates month by month, because compounding makes the straight-line answer optimistic.
Worked Example
- Divide cash by burn. $180,000 ÷ $90,000 is 2.00 months at the current rate — barely time to arrange anything.
- Test whether burn holds flat. Burn that grows compounds. The engine iterates month by month rather than dividing once, because the straight-line answer flatters.
- Look at the balance sheet first. Releasing the $287,584.72 trapped in inventory and receivables extends runway to 5.20 months — cash you already own.
- Size the funding gap. Twelve months at this burn needs $1,080,000. Against $180,000 of cash that is a $900,000 gap before any working-capital release.
- Consider the alternative. Cutting burn to $15,000 a month would reach twelve months on existing cash — an 83.33% reduction, which shows how severe the position is.
The working-capital lever is the one most often missed. This business has 2.00 months of runway and a $900,000 funding gap, which reads as an emergency — but batch 33 established that $287,584.72 is trapped in a 103.74-day cash conversion cycle. Releasing it extends runway to 5.20 months, more than doubling the time available, using cash the business already owns. No dilution, no new debt, no lender approval. It is slower than drawing a facility and faster than raising equity, and it should be the first place any management team looks when runway shortens, because every other option costs either ownership or interest.
Strengths & Limits Of This Model
Where this engine is strong
- Iterates month by month when burn grows, rather than dividing once.
- Reports fractional months, which matters when timing a financing process.
- Presents all three levers: raise, cut, or release working capital.
Where it stops
- Cannot anticipate a revenue recovery that would change the burn entirely.
- Assumes cash on hand is genuinely available rather than restricted.
Practical Use Cases
Deciding when to start a funding process
Raising takes three to six months. Below six months of runway a process started today only just completes, and terms deteriorate as cash falls.
Choosing between cost cuts and a raise
The engine states the burn ceiling that reaches your target on existing cash. If that cut is implausible, the raise is not optional.
Finding cash without dilution
Working capital is usually the largest untapped source. Quantify it with the Cash Conversion Cycle Calculator.
Board reporting under pressure
Report runway alongside burn and the trigger date for action. Pair with the Burn Rate Calculator.
Methodology & Editorial Standards
Runway divides available cash by monthly net burn to express survival in months, and it is the single most important number for any business consuming cash. The simple division assumes burn holds constant, which is rarely true, so the engine also iterates month by month under a user-specified growth rate: burn that rises with headcount compounds, and the straight-line calculation is materially optimistic in that case, while sustained cost reduction compounds in the opposite direction. The engine reports fractional months rather than rounding down, because the difference between two months and two and a half is meaningful when arranging finance. Three levers are presented explicitly: raising capital, sized as the gap between cash needed and cash held; cutting burn, expressed as the monthly ceiling that would reach the target on existing reserves; and releasing working capital, which is frequently the largest and least considered source because it requires no external party and causes no dilution. Conventional guidance is to maintain twelve to eighteen months and to begin raising at around twelve, since a funding process typically takes three to six months to complete and terms deteriorate sharply as cash declines. The engine implements the standard published formula for this calculation. Inputs are validated for domain and sign before evaluation, and any undefined case returns an em-dash rather than a spurious value.
Computation runs in IEEE-754 double precision at full internal precision; rounding to two decimal places occurs strictly at the display layer, so no cumulative drift enters the result. All monetary outputs use accounting presentation — grouped thousands, two decimals, negatives in parentheses — so figures can be transcribed directly into a model or working paper. Division-by-zero and out-of-domain inputs return an em-dash rather than a misleading number.
This engine was reconciled against an independent reference implementation and hand-verified for the worked example above before release. Our full five-stage review process is published on the About Us page.
Disclaimer. This calculator is provided for informational and modelling purposes only and does not constitute financial, tax, legal, medical, or engineering advice. Verify all figures with a qualified professional before acting on them.
Runway Calculator — 20 Expert FAQs
20 analyst-written answers to the questions practitioners actually ask — optimised for voice and answer-engine retrieval.
What is cash runway?
The number of months current cash lasts at the present burn rate. Here $180,000 ÷ $90,000 is 2.00 months.
How much runway should a business keep?
Twelve to eighteen months is the conventional target, because raising capital takes three to six months and terms worsen as cash falls.
When should I start raising?
At around twelve months of runway. Below six months a process may not complete before cash runs out, which destroys negotiating position.
Does burn growth change the answer?
Significantly. Growing burn compounds, so the engine iterates month by month rather than dividing once, which would flatter the result.
Can I extend runway without raising money?
Yes. Releasing $287,584.72 from working capital here takes runway from 2.00 to 5.20 months using cash the business already owns.
What burn would reach my target runway?
Cash divided by target months. For twelve months on $180,000 that is $15,000 a month — an 83.33% reduction from the current rate.
Should runway include debt repayment?
Yes. Principal is a genuine cash outflow, and excluding it overstates runway for any business with amortising debt.
What is a dangerous runway level?
Under six months. Financing takes months to arrange, so the practical options narrow to cost reduction and releasing trapped cash.
Does an undrawn facility count as runway?
Only if it is genuinely available. Facilities with covenant conditions can disappear precisely when performance deteriorates.
How does runway relate to burn rate?
Runway is cash divided by net burn. They are the same fact expressed as time rather than as a monthly rate.
Should I use gross or net burn for runway?
Net burn, since revenue offsets spending. Gross burn would understate runway for any business with meaningful revenue.
What if my business is cash generative?
Runway is unlimited at that level, and the tool becomes a stress test — find the revenue decline at which cash consumption would begin.
How accurate is a runway figure?
It is a projection built on current burn. Its value is in triggering action early, not in predicting an exact date.
Does seasonality affect runway?
Yes. Use a trailing three-month average burn, and check whether the cash-low point falls in a seasonal trough.
Is cutting payroll the fastest way to extend runway?
It is the largest lever for most businesses, but severance costs cash up front and lost capacity can reduce revenue, raising net burn.
Why does runway shorten faster than expected?
Usually working-capital movements. Inventory builds and slow collections consume cash that a simple burn calculation never captures.
Is this runway calculator free to use?
Yes. It is free, requires no account, and has no usage limits. ApexConverter is funded by contextual advertising, never by selling user data.
Is my data sent to a server?
No. The engine runs as Vanilla JavaScript inside your browser under our Zero-Server Client-Side Execution model. Your figures are computed locally and are never transmitted, logged, or stored.
How accurate is this calculator?
It applies the standard closed-form formula in IEEE-754 double precision, rounding only at the display layer. The engine is reconciled against an independent reference implementation before release.
Does it work on mobile?
Yes. The interface is mobile-first with numeric keypad hints and is tested down to a 320-pixel viewport with no horizontal scrolling.