Monthly Budget Planner — 50/30/20 Rule
List every income source and expense by category. CalcWize totals them, shows what's left over, and benchmarks your spending against the 50/30/20 rule (50% needs, 30% wants, 20% savings & debt). Switch between detailed view (line-by-line) and rule view (high-level percentages) to spot where the money is actually going.
How we calculate it
The planner totals your income and expenses, reports what is left over, and compares your spending to the 50/30/20 split — 50% needs, 30% wants, 20% savings and debt repayment — measured against your after-tax income.
The 50/30/20 rule
A simple budgeting framework: spend ~50% of after-tax income on needs (rent, utilities, groceries, transport), 30% on wants (dining, subscriptions, hobbies), and put 20% toward savings, investments, and debt repayment. It's not gospel — adjust the percentages to your situation.
Tip: pipe leftover into investing
When your "Leftover" is positive, the KPI shows a "Use in" button that pipes the amount into the Compound Interest or Retirement Planner as your monthly contribution — instant projection of what consistent saving turns into.
Detailed view vs. rule view
Detailed view lists every income source and expense line by line — best for finding leaks ("how much actually goes on subscriptions?"). Rule view collapses everything into the three 50 / 30 / 20 buckets and shows colour-coded bars for actual vs. target — best for high-level course correction. Switch between them at the top of the calculator.
When 50 / 30 / 20 doesn't fit
The rule was popularised by Senator Elizabeth Warren as an approachable starting point for middle-class US households. It doesn't fit aggressive savers (who push 20 → 40+%), people in expensive cities where rent alone eats 50% of net (no flex left for "wants"), or people in active debt-payoff modes. Treat it as a sanity check, not a contract.
Common mistakes
Two patterns kill the usefulness of a budget: (1) using your gross salary instead of net (post-tax) — you can't spend money you don't see; (2) forgetting irregular expenses (annual insurance premiums, holiday gifts, vehicle service). Add them as monthly averages — divide an annual figure by 12 — so they don't ambush your January.
Frequently asked questions
- Should I use gross or net income?
- Net (after-tax) income. You can only budget money you actually receive; using gross overstates what is available to spend and save.
- What if 50/30/20 doesn’t fit my situation?
- It is a reference, not a rule. Expensive cities, aggressive savers, and active debt-payoff phases all justify different splits. Adjust the targets to your reality.
- How do I handle irregular expenses?
- Convert annual costs such as insurance, gifts, or car servicing into a monthly average by dividing by 12, so they don’t ambush a single month.
What it doesn't do
- Real-time bank-feed reconciliation (this is a planning tool, not bookkeeping)
- Multi-currency budgeting (one currency at a time)
Last reviewed: 2026-05 — Tiaan Fourie