Cash & equivalents ($) Balance sheet, latest 10-Q.

Quarterly operating cash burn ($) Net cash used in operating activities, as a positive number.

Quarterly capex ($, optional)

Debt due within 12 months ($, optional)

Current market cap ($, optional) Used to estimate dilution from the next raise.

Extend runway to (months)

Runway —

Cash exhausted around — From today, at this burn

Monthly burn — Operating + capex

Raise needed —

Implied dilution — If raised at today's market cap

Raise vs market cap — Size of the raise relative to the company

How it works

Monthly burn = (quarterly operating burn + quarterly capex) ÷ 3
Runway = (cash − debt due within 12 months) ÷ monthly burn
Raise needed = (monthly burn × target months) − available cash
Implied dilution = raise ÷ (market cap + raise), i.e. issuing at today's price

Why this is the number that matters

A small-cap that loses money has exactly three options: raise equity, raise debt, or stop. For most micro-caps the first is the only realistic one, which means that the moment the runway gets short, new shares are coming. The chart won't tell you this. The cash flow statement will, a quarter in advance.

Two refinements that make the output more honest:

Subtract debt maturing inside the window. Cash earmarked to repay a note is not available to fund operations, so this calculator removes it before computing runway.
Include capex if it's real. A company building a facility is consuming cash whether or not it shows up in operating activities.

The rule of thumb worth remembering

Companies rarely let the runway reach zero — they raise well before, because raising from a position of visible desperation prices terribly. In practice, expect the raise when runway falls to somewhere around six to nine months, not when the cash is gone. If your calculation says twelve months, the offering may be a quarter or two away, not a year.

What it can't see

Burn isn't constant. One quarter's figure may include a one-off payment or a milestone receipt. Average two or three quarters where you can.
Non-dilutive funding exists. Grants, partnerships, milestone payments, royalty deals and asset sales all extend runway without issuing shares.
The raise may not price at market. Small-cap offerings are usually priced at a discount, and often carry warrants — so real dilution typically exceeds the figure here. Model the actual terms in the dilution calculator once a deal is announced.
Capacity may be capped. Below $75 million of public float, the baby shelf rule limits primary sales to one-third of float per year. A company may be unable to raise as much as it needs in one go.