Financial Boundary Calculator

Monthly Disposable Income is what's left after Monthly Fixed Expenses, a savings set-aside (Monthly Income times Savings Goal %), and Monthly Debt Payments are all subtracted from Monthly Income, floored at zero (lines 17-20). Monthly Income shows the largest effect on that figure under a proportional (e.g. ±10%) nudge, but only because its default base ($5,000) is roughly double Monthly Fixed Expenses' default base ($2,500) — not because each income dollar carries more weight. Dollar-for-dollar it's the opposite: the savings set-aside (line 18) diverts 20 cents of every income dollar before it reaches Disposable Income, so a $1 raise in Monthly Income adds only $0.80, while a $1 cut to Monthly Fixed Expenses adds the full $1.00. A percentage-based nudge on Monthly Income's larger base still moves more absolute dollars than the same-size nudge on Monthly Fixed Expenses' smaller base, which is why it reads as the dominant lever.

Social Budget, Per-Event limits, and Dining Budget are all fixed percentages of Disposable Income (20%, 30%, and 15%, lines 23-41), so Social Events per Month never changes Disposable Income itself — it only changes how that same social budget gets divided per outing (lines 27-32). Gift and vacation budgets work differently: they're percentages of annual gross income (Monthly Income times 12), not of Disposable Income, at 1%-3% for gifts and 5%-10% for vacations (lines 34-37, 43-45). Two outputs — Gift Budget Low and Vacation Budget Low — report the lower end of those ranges (1% and 5% of annual gross income respectively) without their own explanatory text elsewhere on the page; they exist as the floor beneath Annual Gift Budget and Annual Vacation Budget, which both display the higher end (3% and 10%). "Sleep On It" Threshold is 10% of Disposable Income (line 49) — any single purchase above that dollar figure is the calculator's cue to wait a day before buying. This tool has no knowledge of your actual bank balance or spending history.