# Cash-Flow Runway Calculator

> Cash flow runway calculator: turn burn rate and cash balance into months of runway so you know when your startup needs funding. Free, runs in your browser.

- **Canonical URL:** https://boringtoolskit.com/cash-flow-runway-calculator/
- **Category:** Seller & Business
- **Evidence level:** authored-methodology
- **Reviewed:** July 2026
- **Last verified:** 2026-09-20
- **Privacy:** Inputs and results stay in this browser unless the page clearly labels an external request.

## How it works

Starting cash is updated month by month by adding modeled revenue and subtracting modeled expenses; each may compound by its entered monthly change. Runway is the first month ending cash reaches zero or below.

## Worked example

$10,000 starting cash with $2,000 monthly revenue and $3,000 monthly expenses reaches zero at month 10 when both remain constant.

## Assumptions

- Revenue and expenses change at constant monthly rates after month one.
- Financing, taxes, owner draws, and one-time cash flows are excluded unless included in inputs.
- A result beyond the horizon means only that cash stayed positive during the modeled months.

## Common questions

### Is this a forecast?

No. It is a bounded scenario using constant assumptions.

### What does beyond the horizon mean?

Cash remained above zero during the selected months; it does not mean unlimited runway.

### What is operating break-even?

The first modeled month in which revenue is at least expenses before financing and excluded cash flows.

## Related tools

- /break-even-units-calculator/
- /profit-margin-markup-calculator/
- /emergency-fund-calculator/

## Sources

- [Manage your finances](https://www.sba.gov/business-guide/manage-your-business/manage-your-finances)

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