How Pocket Runway Calculates Safe to Spend

Safe to spend is the money left in the current pay period after everything already committed to it, and the daily allowance is that figure divided by the days until your next paycheck. Here is the whole calculation, in the order the app runs it.

Funding          =  paycheck  +  one-time income received
                  +  money carried in  +  recurring income transfers

Committed        =  bills due before the next paycheck
                  +  recurring transfers
                  +  savings and sinking fund reserves
                  +  money moved into goals
                  +  credit card smoothing reserves

Available        =  funding  −  committed

Safe to spend    =  available  −  spending so far this period

Daily allowance  =  safe to spend  ÷  days until the next paycheck

Everything below is that same calculation with each term explained. Figures in the examples are illustrative.

Where a pay period starts and ends

A pay period runs from the paycheck that opened it up to, but not including, the day your next paycheck lands. The next paycheck funds its own period.

The boundary is an instant rather than a calendar day. Your paycheck clear time, set in the app and applied in your own timezone, is what decides which side of the boundary a purchase made on payday morning falls on. Without that, spending at 8am on payday would be charged to a period that had not opened yet.

A period does not roll over automatically. When your payday arrives, the app asks you to confirm the paycheck actually landed, and the new period begins when you say so. Employers pay early, pay late and skip holidays, and a plan that assumes money arrived because the calendar said so is a plan that is wrong exactly when it matters.

Funding: what the period has to work with

The paycheck. The amount from your pay schedule, or the amount you confirmed if it differed.

One-time income already received. Money logged as income that has actually landed inside the period. Income dated in the future is excluded: it is real, but it is not yet available, and letting it raise today's number is how a forecast funds today's spending.

Money carried in. Whatever was left when the previous period closed. If you completed a Runway Reset, this is the figure you confirmed. If you did not, it is inferred from the cash actually in your spending accounts, which keeps the number honest rather than optimistic.

Recurring income transfers. Regular money you move in from elsewhere, if you have set any up.

Committed: what is already spoken for

Each of these is charged to the period exactly once.

Bills due before the next paycheck. Only the occurrences that actually fall inside this window. A bill due after your next payday belongs to that period, not this one, and reserving it now would understate what you have. This is the single biggest difference from a monthly budget.

Recurring transfers. Regular moves to savings or elsewhere that you have scheduled.

Savings, goals and sinking fund reserves. A goal's per-paycheck contribution is reserved for the period. When you actually move money into a goal, that transfer satisfies the reserve instead of adding to it: the period commits whichever is larger, the planned reserve or what you actually moved, never the sum. Funding a goal that already reserved enough therefore costs the period nothing, because it converts a promise into a completed move.

Credit card smoothing reserves. If you are spreading a card balance across several periods, the share for this period is reserved here. Card payoff is handled as one consolidated reserve per card rather than as individual bills, so a charge cannot be reserved twice.

Tax reserves. A self-employed tax reserve behaves like any other committed money: it comes off before the spending figure, which is the point of it.

Spending, refunds and corrections

Spending so far is everything you have logged inside this period. Spending logged on a future date is not counted yet, since it has not happened.

A refund is negative spending. It reduces the total and raises safe to spend back, rather than being treated as new income. That distinction matters: income would raise the period's funding, and a refund is money coming back rather than money arriving.

A purchase that pays a reserved bill is not counted twice. When you record spending against a bill that this period has already reserved, it settles the reserve instead of adding to your ordinary spending. Otherwise paying your rent would reduce your safe-to-spend figure by rent twice, once when it was reserved and once when it was paid.

A correction to an account balance can be applied as a true-up. That adjusts the figure by the difference rather than by the whole balance, so correcting a balance does not erase the period's history.

The minimum buffer is compared, not subtracted

This one is worth being precise about, because it is easy to assume otherwise.

Your minimum buffer is a floor you have told the app you want to protect. It is not taken out of safe to spend. It is compared against what is left, and it drives the pacing signals: whether the period reads as safe, tight or at risk, and whether your daily pace is on track to leave the buffer intact at the end.

The daily spending allowance calculator on this site does subtract a buffer, because a one-off calculation has no way to track a pace over time. The app has your history, so it can do the more useful thing and tell you whether your current rate of spending will land above or below the floor.

Days, and the daily allowance

Days remaining counts today and every day up to but not including your next payday. Today the 3rd with a paycheck on the 10th is seven days, the 3rd through the 9th.

The daily allowance is safe to spend divided by those days. It is a ceiling rather than a target: a quiet day pushes tomorrow's figure up, and a heavy one pulls it down.

Today's remaining allowance is the daily figure minus what you have already spent today, and it stops at zero rather than going negative. A heavy day does not create a debt against tomorrow, it just means tomorrow's share is smaller.

When the numbers go negative

Safe to spend can be negative, and the app shows it as negative rather than as zero. It means the money committed to this period is more than the period has, and the size of the gap is the useful part. The status changes accordingly, and a negative number found on the 3rd is a problem with days left to solve it, which is the entire reason for not hiding it.

Three numbers that are not the same

Your account balance is what the bank says. It still contains money for bills that have not been paid yet, so it is always the most optimistic figure and the one most likely to mislead.

Safe to spend is what is left for the rest of this pay period after everything committed to it.

The daily allowance is that figure spread over the days remaining.

The forecast is the same calculation applied to pay periods that have not started yet, using your scheduled pay and your known bills. It is a projection, so it changes as reality does, and nothing in it affects the current period's number.

Future periods, and why they stay out of today

Future income never raises today's safe to spend. Your next paycheck sets the end of the current period and funds the next one. The forecast shows the periods ahead, including which of them are already heavily committed, so an overloaded period is visible in advance without changing what is spendable now.

If you want to see which paycheck each bill lands on, the paycheck allocation calculator does that in isolation, and the app does it continuously.

Runway Reset

When a period ends, Runway Reset is the closeout. It asks you to confirm what the paycheck actually was, shows what is left over, and asks what you want to do with it: carry it forward, move it to savings, put it toward a goal or against debt.

Whatever you confirm is what carries into the next period. That is why a confirmed reset produces a more accurate carried-in figure than the inference used when a period is left unclosed.

Purchase simulation

The what-if tool answers "what happens to the rest of this period if I spend this?" by running the same calculation with one extra transaction added to a copy of the inputs. Nothing is saved, no balance moves, and the answer you get is produced by the same engine that produces your real number rather than by a simplified version of it.

Rounding

Every figure in the calculation is computed and stored to the cent. Some displays abbreviate larger amounts for readability, so a screen may show a rounded form of a number that is exact underneath. The daily allowance is a division, so it is the figure most likely to show a rounded value.

Worked example 1: an ordinary biweekly period

Illustrative figures.

Paid every two weeks. Today is the 3rd, the next paycheck lands on the 17th, so the period has 14 days left including today.

Paycheck                              1,800.00
Carried in from last period             120.00
Funding                               1,920.00

Rent, due the 5th                       950.00
Electric, due the 12th                  110.00
Phone, due the 14th                      55.00
Transfer to savings                     100.00
Car insurance sinking fund               65.00
Committed                             1,280.00

Available                               640.00
Spending so far this period              85.00
Safe to spend                           555.00

Daily allowance  =  555.00 ÷ 14  =       39.64

The bank might show around $1,835 in the account at this point. The difference is the $1,115 of bills and transfers that have not left yet. The minimum buffer, say $200, is not subtracted from the $555, but if spending continues at a pace that would end the period below $200, the pacing signal says so.

Worked example 2: the same period after three changes

Same period, four days later. A $40 refund came back, the paycheck was $120 lower than scheduled, and an unplanned $180 car repair happened.

Paycheck, as confirmed                1,680.00
Carried in from last period             120.00
Funding                               1,800.00

Committed, unchanged                  1,280.00
Available                               520.00

Spending so far                         340.00
  (85.00 earlier, plus 180.00 repair,
   plus 115.00 ordinary, less a 40.00 refund)
Safe to spend                           180.00

Daily allowance  =  180.00 ÷ 10  =       18.00

Three things to notice. The refund reduced spending rather than adding income. The smaller paycheck reduced funding, not the committed bills, because the bills did not change. And the daily allowance dropped by more than half, which is the mechanism working: the adjustment arrives while there are ten days left to absorb it rather than as a shortfall discovered at the end.

What this page does not cover

This is a description of the financial model, not documentation of the software. It leaves out the internal detail of how figures are stored, secured and reconciled. Security and privacy covers how your data is handled.

Get started with Pocket Runway

This page is general educational information about how Pocket Runway works, not financial, tax or legal advice. Every figure in the examples is illustrative. Details of the calculation can change as the product develops; the app itself is always the authority on your own numbers.