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Finance & LoansGenerated accuracy model review: 2026-05-06
Budget Calculator accuracy and testing
This page documents how Calwarden builds trust for this calculator: source notes, regression-style default tests, limitations, assumptions, unit handling, rounding, and visible change history.
Formula source
- The calculator takes your Net Income and applies the following percentages: • **50% Needs**: Essential expenses you cannot avoid (Rent, Utilities, Groceries, Insurance). • **30% Wants**: Discretionary spending (Dining out, Hobbies, Subscriptions). • **20% Savings**: Future self (Retirement contributions, Emergency fund, Debt repayment).
Test cases
Default input regression check
Generated from the checked-in default inputs and calculate function.
Inputs
- Monthly Net Income: $4,000
Expected outputs
- Needs (50%): $2,000.00
- Wants (30%): $1,200.00
- Savings (20%): $800.00
Known limitations
- This rule works best for moderate to high incomes. Low-income earners often must spend >50% on Needs just to survive.
Assumptions
- Inputs are interpreted exactly as entered in the calculator form.
- The calculation runs locally in the browser using the current checked-in calculator definition.
Unit handling
- Monthly Net Income accepts values in $.
- Needs (50%) is displayed as currency.
- Wants (30%) is displayed as currency.
- Savings (20%) is displayed as currency.
Rounding rules
- Number displays use up to 2 decimal places in the calculator UI.
- Currency outputs are displayed with standard US dollar formatting.
Version history
1.0.0 - 2026-05-06
Generated accuracy and testing page from the current budget-calculator calculator definition.
Change log
2026-05-06
Published default regression test documentation and metadata fallbacks for Budget Calculator.
Calculator transparency
Accuracy pages are generated from checked-in calculator definitions and can be upgraded with curated review metadata over time.