Now in the almanacThe almanac turns by the month

Fieldnote Financial

Tool two · the reserve runway

How many months would your reserve carry the household?

Put in what you have put by and what a month of essentials costs. The dial fills clockwise, one segment for each month, from whichever month you choose, and a second lap shows anything beyond a year.

Your figures

Whole numbers or decimals; commas are fine. Nothing leaves this page.

Housing, food, utilities, minimum payments, work costs that must continue, and cover you intend to keep. See the list below.

Only count income you are sure of in a lean stretch, such as a partner’s wage. Leave blank to count none.

The runway dial

  • First lap: months 1 to 12
  • Inner lap: months 13 to 24

The dial is waiting

Enter what you have put by and what a month of essentials costs.

Using the calculator

What goes in, and what the answer means

What counts as an essential

Essentials are the costs that would still arrive if no income did. The aim is a bare-bones month, not a comfortable one. Count the roof, the food, the power and water, the phone you need for work, the minimum payments on debts, the fuel or fares to get to work, medical costs you cannot skip, childcare you cannot do without, and the insurance you have decided to keep.

Usually counted

  • Rent or mortgage, and rates or property charges
  • Utilities, phone and internet used for work
  • Food and basic household supplies
  • Minimum loan and credit payments
  • Business costs that cannot pause: storage, licences, equipment loans, feed
  • Premiums on cover you intend to keep

Usually left out

  • Holidays, eating out, upgrades and gifts
  • Extra payments above the minimum
  • New equipment you could delay
  • Money you would normally put by

How to read the dial

Each segment of the outer ring is one month of runway, filled clockwise from the month you choose. A partly filled segment is a partly covered month. If the reserve lasts more than a year, the inner ring (hatched) carries on for months thirteen to twenty-four. The start month is marked with a dark label, and the big number in the middle is the runway in months, shown as 24+ once the dial is full.

The headline sentence under the dial says the same thing in words, including the month in which the money would run out. The same figure appears in the “Runway” card as years and months once it passes two years.

What the calculator leaves out

  • It is not a forecast. It assumes costs stay where you typed them. The “If costs moved” table shows what ten or twenty percent either way would do.
  • One-off bills. A vehicle repair or a big annual renewal is not in a monthly figure. Add a share of such bills to your essentials, or keep a separate pot for them.
  • Other income. If you count money still coming in, only count what is dependable. If it covers essentials entirely, the dial shows “Covered” rather than a number of months.
  • Zero reserve. A reserve of zero gives a runway of zero. That is a starting point, not a verdict; the goal section shows how long a monthly saving takes to reach a target.
  • Interest and inflation. Savings growth and rising prices are not modelled. Treat the result as a round-number guide, not a promise.
  • Where it lives. Your figures are kept in this browser only. Clearing site data, or using a private window, forgets them.