Calculator Inputs
Example Data Table
| Item | Example | Why it matters |
|---|---|---|
| Evaluation period | 12 months | Longer history improves confidence. |
| Monthly income series | 3500, 3600, 3550, 3700, 3650, 3600, 3750, 3800, 3700, 3850, 3900, 4000 | Used for volatility, gaps, and trend. |
| Expected minimum | 3000 | Months below this are gaps. |
| Employment type | Salaried | Lower risk reduces penalties. |
| Tenure | 18 months | Longer tenure increases stability. |
| Source averages | Primary 3200, Secondary 500, Other 0 | Diversification reduces reliance risk. |
| Fixed obligations | 900 | Coverage supports repayment resilience. |
| Savings buffer | 2 months | Adds a small stability bonus. |
| Result | Score 72.2, Tier Good | Shows reliable income with mild trend. |
Formula Used
This calculator converts income patterns into a 0 to 100 score.
- Average income:
avg = sum(income) / months - Volatility:
std = sqrt( sum((x-avg)^2) / months ) - Coefficient of variation:
cv = std / avg - Consistency score:
100 × (1 − min(cv,1.5)/1.5) - Trend score:
50 + 50 × clamp(growthRate, −1, 1) - Gap score:
100 − 120 × (gapMonths / months) - Diversification score:
100 × (1 − maxShare) - Tenure score:
100 × clamp(tenure/24, 0, 1)
Base score uses weighted components:
base = 0.35×consistency + 0.20×trend + 0.15×gaps + 0.10×diversification + 0.20×tenure
Adjusted score applies quality factors and adds a buffer bonus:
final = clamp( base × (employment × documentation × industry × coverage) + savingsBonus, 0, 100 )
How to Use This Calculator
- Choose a period, then gather monthly income totals.
- Enter exactly one value per month in the series.
- Set an expected minimum to flag low-income months.
- Select employment, tenure, documentation, and industry details.
- Add obligations and buffer months for resilience adjustments.
- Click calculate, then export the result if needed.
What the score represents
The Income Stability Score converts several income signals into a 0–100 index. Higher values indicate steadier cash flow, longer tenure, fewer gaps, and less concentration in one source. Lenders often treat stability as a proxy for repayment reliability, especially when income is variable. For clearer credit decisions.
Key inputs and weighting
Base scoring blends five components: consistency (35%), trend (20%), gaps (15%), diversification (10%), and tenure (20%). Consistency uses the coefficient of variation, CV = σ/μ, where σ is the population standard deviation and μ is the mean. Trend measures growth from the first month to the last month, capped between −100% and +100%. All component scores are clamped to the 0–100 range. Tenure scales to 24 months; 12 months equals 50 points. Diversification rises when no source dominates totals for most applicants.
Reading volatility and gaps
If CV is near 0.20, income is typically very steady; above 0.80, volatility is noticeable; near 1.50, stability is weak. Gap months count any month below the expected minimum income. A higher gap share reduces the gap score, which is designed to penalize frequent shortfalls more than rare dips.
Documentation and coverage adjustments
After the base score, the calculator applies multiplicative factors for employment type, documentation strength, and industry volatility. A coverage factor reflects whether average income can absorb fixed obligations; higher obligations reduce the factor and lower the adjusted score. Diversification is estimated by the largest income-share across sources, rewarding balanced mixes. The tool also adds a savings buffer bonus of up to 6 points, based on months of expenses covered by reserves.
Action steps to lift stability
To improve results, reduce month‑to‑month swings by smoothing billings, building retainer work, or staging invoices. Maintain clear records so documentation stays strong. Lower fixed obligations relative to average income, or raise income with predictable contracts. Aim for 65+ for “Good” and 80+ for “Strong”. Finally, grow emergency savings to add buffer points and reduce lender risk.
FAQs
What period should I choose?
Use 12 months for a balanced view. If income is seasonal, select 18–24 months. Shorter windows react faster to recent changes but may overstate temporary spikes or dips.
What score range is considered good?
Scores of 65–79 suggest generally reliable income. Scores of 80+ indicate strong stability. Below 50 often signals volatility, gaps, or short tenure that may require larger buffers or tighter budgets.
Why does expected minimum income matter?
It sets the threshold for identifying shortfall months. If your minimum is too high, normal fluctuations look like gaps. If it is too low, true shortfalls may be hidden and the gap component becomes less informative.
How are income gaps calculated?
Any month in the series below the expected minimum counts as a gap month. The gap score declines as the share of gap months rises, so frequent shortfalls reduce stability more than an occasional low month.
How does savings affect the result?
Savings are treated as a resilience bonus. Each month of expense coverage adds points up to a capped maximum. It won’t fix extreme volatility, but it can lift borderline scores and improve the overall risk tier.
Can self‑employed or gig workers use it?
Yes. Enter your monthly totals and choose the matching employment type. Strong documentation and diversified sources help offset variability. If income is irregular, using a longer period often produces a more representative score.