Budget Calculator
This budget calculator helps you compare your actual monthly spending to recommended allocation frameworks (50/30/20, zero‑based budgeting) and to custom percentage targets. Enter your gross monthly income and recurring category amounts to see totals, gaps, and suggested next steps.
Use the different methods to explore tradeoffs: the 50/30/20 rule provides a quick target split for needs, wants, and savings; zero‑based budgeting shows unallocated dollars that should be assigned; and custom allocation lets you set your own target percentages.
Governance
Record af87ee950d14 • Reviewed by Fidamen Standards Committee
Allocates 50% of income to needs, 30% to wants, and 20% to savings/debt reduction. Compares each allocation to your entered categories to show gaps.
Inputs
Results
Needs recommended (50%)
$2,500.00
Wants recommended (30%)
$1,500.00
Savings recommended (20%)
$1,000.00
Actual needs (entered)
$2,500.00
Actual wants (entered)
$250.00
Actual savings (entered)
$500.00
Needs gap
$0.00
Wants gap
-$1,250.00
Savings shortfall
$500.00
| Output | Value | Unit |
|---|---|---|
| Needs recommended (50%) | $2,500.00 | USD |
| Wants recommended (30%) | $1,500.00 | USD |
| Savings recommended (20%) | $1,000.00 | USD |
| Actual needs (entered) | $2,500.00 | USD |
| Actual wants (entered) | $250.00 | USD |
| Actual savings (entered) | $500.00 | USD |
| Needs gap | $0.00 | USD |
| Wants gap | -$1,250.00 | USD |
| Savings shortfall | $500.00 | USD |
Visualization
Methodology
Calculations use straightforward arithmetic based on your entered monthly amounts. All percentage allocations are applied to gross monthly income unless stated otherwise.
This tool is an estimator intended for planning and education. It is not a substitute for professional financial advice. For security and reliability design guidance, computations and UI follow general best practices consistent with NIST digital identity and usability recommendations and ISO/IEEE interface guidance where applicable.
Outputs show both recommended allocation amounts and comparisons to your entered values so you can identify where to reassign dollars, increase savings, or cut discretionary spending. Data validation is limited to non‑negative numeric checks on inputs.
Worked examples
Example 1: Income $5,000; total expenses $4,200. Surplus $800 (16% of income). Under 50/30/20, savings target = $1,000; if current savings are $500, savings shortfall = $500.
Example 2: Income $3,000; after assigning categories your zero‑based unallocated = -$200 (shortfall). Actions: increase income, reduce discretionary categories, or reassign planned savings temporarily.
F.A.Q.
How accurate is this calculator?
This calculator produces estimates based on the numbers you enter. It does not model taxes, irregular income, or one‑time expenses unless entered. Results should be used for planning, not as definitive financial advice.
Which method should I use?
Use the actual budget method to understand current cash flow. Use 50/30/20 for a simple target split. Use zero‑based budgeting to ensure every dollar has a purpose. Use custom allocation to set personalized targets. Choose the method that fits your planning goals.
Do you account for taxes and pre‑tax deductions?
Inputs assume gross monthly income. If you prefer, enter net (take‑home) income instead and treat outputs as percentages of take‑home pay. For formal tax or benefit impacts consult a tax professional.
Can I track irregular or annual expenses?
Yes. Convert annual or irregular costs to monthly equivalents before entering (annual cost ÷ 12). The calculator treats all inputs as monthly amounts.
Is my data stored or shared?
This tool is a client‑side estimator. Follow the hosting site's privacy practices. For enterprise deployments follow NIST and ISO guidance for data protection and secure UI design.
Sources & citations
- NIST Digital Identity Guidelines — https://www.nist.gov/itl/ssd
- ISO standards overview — https://www.iso.org/standards.html
- IEEE user interface recommendations — https://www.ieee.org
- OSHA workplace guidelines (for financial wellness programs) — https://www.osha.gov
- CFPB — Consumer Financial Protection Bureau — https://www.consumerfinance.gov/
- Federal Reserve — Consumer Credit — https://www.federalreserve.gov/releases/g19/current/
- IRS Publication 17 — Your Federal Income Tax — https://www.irs.gov/publications/p17
Further resources
Versioning & Change Control
Audit record (versions, QA runs, reviewer sign-off, and evidence).
Record ID: af87ee950d14What changed (latest)
v1.0.0 • 2025-11-21 • MINOR
Initial publication and governance baseline.
Why: Published with reviewed formulas, unit definitions, and UX controls.
Public QA status
PASS — golden 25 + edge 120
Last run: 2026-01-23 • Run: golden-edge-2026-01-23
Versioning & Change Control
Audit record (versions, QA runs, reviewer sign-off, and evidence).
What changed (latest)
v1.0.0 • 2025-11-21 • MINOR
Initial publication and governance baseline.
Why: Published with reviewed formulas, unit definitions, and UX controls.
Public QA status
PASS — golden 25 + edge 120
Last run: 2026-01-23 • Run: golden-edge-2026-01-23
Engine
v1.0.0
Data
Baseline (no external datasets)
Content
v1.0.0
UI
v1.0.0
Governance
Last updated: Nov 21, 2025
Reviewed by: Fidamen Standards Committee (Review board)
Credentials: Internal QA
Risk level: low
Reviewer profile (entity)
Fidamen Standards Committee
Review board
Internal QA
Entity ID: https://fidamen.com/reviewers/fidamen-standards-committee#person
Semantic versioning
- MAJOR: Calculation outputs can change for the same inputs (formula, rounding policy, assumptions).
- MINOR: New features or fields that do not change existing outputs for the same inputs.
- PATCH: Bug fixes, copy edits, or accessibility changes that do not change intended outputs except for previously incorrect cases.
Review protocol
- Verify formulas and unit definitions against primary standards or datasets.
- Run golden-case regression suite and edge-case suite.
- Record reviewer sign-off with credentials and scope.
- Document assumptions, limitations, and jurisdiction applicability.
Assumptions & limitations
- Uses exact unit definitions from the Fidamen conversion library.
- Internal calculations use double precision; display rounding follows the unit's configured decimal places.
- Not a substitute for calibrated instruments in regulated contexts.
- Jurisdiction-specific rules may require official guidance.
Change log
v1.0.0 • 2025-11-21 • MINOR
Initial publication and governance baseline.
Why: Published with reviewed formulas, unit definitions, and UX controls.
Areas: engine, content, ui • Reviewer: Fidamen Standards Committee • Entry ID: 29cc018e4204