What is the budget calculator?
In short
The 50/30/20 rule allocates 50% of after-tax income to needs, 30% to wants, and 20% to savings. On $5,000/month take-home, that's $2,500 for necessities, $1,500 for fun, and $1,000 saved.
This budget calculator categorises your monthly spending into needs, wants, and savings, compares each category against the 50/30/20 targets, and shows where you're over or under budget. A donut chart and comparison table make the gaps visual.
How to use this calculator
- 1Enter your monthly after-tax income.
- 2Fill in your actual spending in each needs category.
- 3Fill in your wants spending.
- 4Enter your monthly savings, investments, and extra debt payments.
- 5Review the donut chart and comparison table to find where to adjust.
The formula
- I
- — Monthly after-tax income
- N
- — Monthly needs spending (housing, food, utilities, etc.)
- W
- — Monthly wants spending (dining, entertainment, etc.)
- S
- — Monthly savings + debt repayments
Worked example
The scenario
Monthly income: $5,000. Needs: $2,200 (44%), Wants: $550 (11%), Savings: $750 (15%). Unallocated: $500.
The result
Needs are under the 50% target — great. Savings at 15% are below the 20% target. Consider moving $250 of the $500 unallocated into savings to hit 20%.
Common use cases
- Building a first budget without over-complicating it
- Identifying whether overspending is in needs or wants
- Deciding how much more to save for a specific goal
- Sharing a clear budget summary with a partner
Limitations & assumptions
- 50/30/20 is a guide, not a rule — high-cost cities may force needs above 50%.
- Income should be after-tax; use the Salary Calculator to find this.
- Does not account for irregular expenses like car repairs or medical bills.
Frequently asked questions
Who created the 50/30/20 rule?
What counts as a need vs. a want?
Is 50/30/20 realistic in expensive cities?
Where do debt payments go?
What if I have an unallocated surplus?
Disclaimer: KalkWise calculators are provided for general informational and educational purposes only and do not constitute financial, investment, tax, or legal advice. Results are estimates based on the figures you enter and the assumptions described above. Actual outcomes will vary. Consult a qualified professional before making financial decisions.