Single Income Budget Calculator

A single-income household carries risk that a dual-income one doesn't — there's no second paycheck to fall back on if something goes wrong — so this calculator pairs a standard budget breakdown with a vulnerability score meant to surface that risk. Housing, transportation, insurance, and savings targets are set as percentages of net income (30%, 12%, 8%, and 10% respectively), while food and utilities scale with household size instead: food starts at a $300 base plus $150 per dependent, and utilities at $100 plus $30 per dependent, reflecting that these costs track people in the home more than they track income level. If childcare is toggled on, it's multiplied by the number of dependents (with a floor of one), since childcare cost is inherently per-child rather than a flat household expense. Essential expenses sum your actual housing payment (not the 30% target) plus the food, transport, utility, insurance targets, and childcare cost, and monthly surplus is simply income minus that total.

The vulnerability score adds points on a 0-100 scale for specific risk factors: housing above 35% of income (+25), more than two dependents (+15), a thin surplus under $200/month (+30), a household with dependents but no childcare — flagged as potentially limiting the earner's work flexibility (+10), and an outright monthly deficit (+20). These thresholds are heuristic judgment calls, not derived from any formal risk model, so the score is meant as a directional signal — "pay attention to housing cost" or "build more cushion" — rather than a precise risk percentage. The calculator also doesn't distinguish which parent is the earner, doesn't factor in disability or life insurance (which matter more when only one income exists), and assumes take-home pay is already net of taxes and deductions.