Assessing Financial Health with the Private Company Z'-Score
The Altman Z'-Score Calculator adapts the original bankruptcy prediction model for private companies by using book value of equity instead of market capitalization. Enter your balance sheet and income statement data to get the Z'-Score, zone classification, and a component-by-component breakdown showing which factors drive the score. A score above 2.9 indicates safety, 1.23–2.9 is the Grey Zone, and below 1.23 signals distress in 2026.
The Z'-Score Formula for Private Companies
The private company variant uses different coefficients than the public company model:
X1 = Working Capital / Total Assets (liquidity)
X2 = Retained Earnings / Total Assets (cumulative profitability)
X3 = EBIT / Total Assets (operating profitability)
X4 = Book Value of Equity / Total Liabilities (solvency — book value, not market)
X5 = Sales / Total Assets (asset turnover)
Z'-Score = 0.717×X1 + 0.847×X2 + 3.107×X3 + 0.420×X4 + 0.998×X5
Key differences from the public company Z-Score (1.2, 1.4, 3.3, 0.6, 1.0):
- X4 uses book value of equity instead of market value
- All coefficients are recalibrated for the private company dataset
- Zone thresholds differ: Safe ≥ 2.9 (vs 2.99), Distress < 1.23 (vs 1.81)
Worked Example: Private Manufacturing Firm
A private manufacturing firm has: Working Capital $1,000,000, Total Assets $5,000,000, Retained Earnings $2,000,000, EBIT $800,000, Book Value of Equity $3,000,000, Total Liabilities $2,000,000, Annual Sales $10,000,000.
- X1 = $1,000,000 / $5,000,000 = 0.2000 → Weighted: 0.717 × 0.20 = 0.1434
- X2 = $2,000,000 / $5,000,000 = 0.4000 → Weighted: 0.847 × 0.40 = 0.3388
- X3 = $800,000 / $5,000,000 = 0.1600 → Weighted: 3.107 × 0.16 = 0.4971
- X4 = $3,000,000 / $2,000,000 = 1.5000 → Weighted: 0.420 × 1.50 = 0.6300
- X5 = $10,000,000 / $5,000,000 = 2.0000 → Weighted: 0.998 × 2.00 = 1.9960
Z'-Score = 0.1434 + 0.3388 + 0.4971 + 0.6300 + 1.9960 = 3.61 → Safe Zone (above 2.9)
The largest contributor is X5 (Turnover) at 1.996 points, accounting for 55% of the total score. The smallest is X1 (Liquidity) at 0.143 — improving working capital offers the best marginal gain.
Zone Thresholds for Private Companies
| Zone | Z'-Score | Interpretation | Action |
|---|---|---|---|
| Safe Zone | ≥ 2.9 | Low bankruptcy risk — financially stable | Continue monitoring quarterly |
| Grey Zone | 1.23 – 2.9 | Moderate risk — could go either way | Investigate weak ratios, increase monitoring |
| Distress Zone | < 1.23 | High bankruptcy risk within 2 years | Urgent review — improve profitability and reduce debt |
Note that these thresholds differ from the public company model (Safe > 2.99, Distress < 1.81) because the private company coefficients are calibrated differently.
Public vs Private Z-Score: Key Differences
| Feature | Public (Z-Score) | Private (Z'-Score) |
|---|---|---|
| X4 Input | Market value of equity | Book value of equity |
| Coefficients | 1.2, 1.4, 3.3, 0.6, 1.0 | 0.717, 0.847, 3.107, 0.420, 0.998 |
| Safe Threshold | > 2.99 | ≥ 2.9 |
| Distress Threshold | < 1.81 | < 1.23 |
| Best For | Publicly traded companies | Private companies, subsidiaries |
The Z'-Score's lower distress threshold (1.23 vs 1.81) reflects that private company financial data tends to be less volatile than public market valuations, so the model requires a lower bar for distress classification.
Limitations and Best Practices
The Z'-Score shares limitations with the public model:
- Industry bias — Originally developed for manufacturing. Service or tech firms with few tangible assets may score differently.
- Book value dependency — X4 uses book equity, which can lag behind actual economic value, especially for asset-light businesses or companies with significant intangible assets.
- Historical data — The score reflects past performance. Supplement with forward-looking cash flow projections and qualitative analysis of management, market position, and industry trends.