Disability Insurance Calculator Formula

Understand the math behind the disability insurance calculator. Each variable explained with a worked example.

Use the Disability Insurance Calculator

Formulas Used

Target Monthly Benefit

target_benefit = monthly_income * coverage_pct / 100

Monthly Income Gap

income_gap = max(monthly_expenses - other_income, 0)

Annual Benefit Needed

annual_benefit = monthly_income * coverage_pct / 100 * 12

Variables

VariableDescriptionDefault
monthly_incomeMonthly Gross Income(USD)6000
monthly_expensesMonthly Essential Expenses(USD)4000
other_incomeOther Monthly Income (Spouse, etc.)(USD)0
coverage_pctTarget Replacement Rate(%)60

How It Works

Why Disability Insurance Matters

Disability insurance replaces a portion of your income if illness or injury prevents you from working. Most policies cover 50-70% of your gross income.

Key Considerations

  • Short-term disability: Covers 3-6 months, often provided by employers
  • Long-term disability: Kicks in after short-term ends, can last until age 65
  • Own-occupation vs any-occupation: Own-occupation pays if you cannot do YOUR specific job

    • Formula

    Monthly Benefit = Monthly Gross Income x Replacement Rate

    Worked Example

    $6,000 monthly income with 60% replacement target.

    monthly_income = 6000monthly_expenses = 4000other_income = 0coverage_pct = 60
    1. 01Target benefit = $6,000 x 60% = $3,600/month
    2. 02Income gap = $4,000 expenses - $0 other income = $4,000
    3. 03Annual benefit needed = $3,600 x 12 = $43,200

    Ready to run the numbers?

    Open Disability Insurance Calculator