Living on One Income Calculator
Whether your household can live on a single income.
Assess whether your household can live on one income by comparing essential spending to the smaller of your two incomes.
What this tool does
Enter both incomes and essential monthly spending. The tool shows whether the larger income covers essentials and by how much.
Enter Values
Formula Used
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Disclaimer
Results are estimates for educational purposes only. They do not constitute financial advice. Consult a qualified professional before making financial decisions.
Many couples want to know whether one could stop working — maternity leave, caring for a parent, job loss, or sabbatical. The single-income viability test is simple: essential monthly spending against the larger income. A 3,000 larger income against 2,500 essential spending leaves 500/month — viable but tight. Against 3,200 essentials, not viable without spending cuts. Running the numbers before the transition is far better than after.
A worked example
Try the defaults: income a of 3,000, income b of 2,000, essential monthly spending of 2,500. The tool returns 500.00. You can adjust any input and the result updates as you type — no submit button, no reload. That's the real power here: seeing how sensitive the output is to one or two assumptions.
What moves the number most
The result responds to Income A (net monthly), Income B (net monthly), and Essential Monthly Spending. Not every input has equal weight. Flip one at a time toward extreme values to feel which ones move the needle most for your situation.
The formula behind this
The larger income vs essential spending. Positive = viable; negative = shortfall that must be cut or filled. Everything the calculator does is shown in the formula box below, so you can check the math against your own spreadsheet if you want.
Reading projections honestly
Point estimates feel certain. They shouldn't. Run the calculation at least twice with a pessimistic and optimistic rate — the spread tells you how much trust to place in the central figure.
What this doesn't capture
Real plans get re-run against new information every year or two. The result here is a reasonable direction, not a destination. Treat it as a starting point for thinking, not a commitment to a specific future.
Single-income viability produces a surplus or shortfall based on the inputs provided.
Inputs
This example uses typical values for illustration. Adjust the inputs above to match a specific situation and see how the result changes.
Sources & Methodology
Methodology
The larger income vs essential spending. Positive = viable; negative = shortfall that must be cut or filled.
Frequently Asked Questions
Why only essential spending?
Should I use gross or net income?
What counts as essential?
Should I plan for both incomes then lose one?
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