What combined ratio measures
The combined ratio compares insurance losses and underwriting expenses with earned premium. A ratio below 100 percent indicates an underwriting profit, while a ratio above 100 percent indicates an underwriting loss before investment income.
The ratio is useful because it separates the insurance operation from the investment portfolio. An insurer can report net income because investment returns are strong, while still having an unprofitable underwriting book.
- Loss ratio measures claims relative to premium.
- Expense ratio measures underwriting expenses relative to premium.
- Combined ratio adds those two pressures together.
How to calculate
Use the formula combined ratio = loss ratio + expense ratio. Loss ratio = incurred losses and loss adjustment expenses / earned premium. Expense ratio = underwriting expenses / earned premium, or sometimes expenses / written premium depending on the reporting convention.
For example, an insurer has $68 million of incurred losses and LAE, $27 million of underwriting expenses, and $100 million of earned premium. Loss ratio is 68 percent, expense ratio is 27 percent, and combined ratio is 95 percent. The underwriting result is approximately $5 million favorable before investment income.
Interpreting the result
A 95 percent combined ratio does not mean the company keeps 95 percent of premium. It means losses and expenses consume 95 cents of each premium dollar, leaving 5 cents of underwriting margin. A 108 percent ratio means losses and expenses consume $1.08 for each premium dollar.
Context matters. Catastrophe-heavy lines, new growth books, long-tail liability lines, and runoff portfolios can have ratios that move for different reasons. Compare the ratio across time, by line of business, and against pricing assumptions.
Who uses the ratio
Underwriters use combined ratio to evaluate pricing adequacy and risk selection. Finance teams use it in planning, investor reporting, and reinsurance analysis. Product managers use it to decide whether rate changes, form changes, or distribution changes are needed.
Agents and program administrators may also track combined ratio at a portfolio level, but they should avoid overreacting to small samples. A handful of large claims can distort a narrow segment.
Common mistakes
The biggest mistake is mixing earned premium with written premium inconsistently. Loss ratios usually use earned premium because claims relate to coverage already provided. Expense ratios may be reported on different bases, so document the basis before comparing results.
Another mistake is ignoring reserve development. Incurred losses include paid losses plus case reserves and incurred-but-not-reported estimates, so a low combined ratio can deteriorate later if reserves strengthen.
Frequently asked questions
Is a combined ratio under 100 always good?
It generally indicates underwriting profit, but the quality of the result depends on reserve adequacy, catastrophe experience, growth, and whether expenses are fully allocated.
Does combined ratio include investment income?
No. Combined ratio measures underwriting results before investment income, taxes, and many non-underwriting items.
What is the difference between loss ratio and combined ratio?
Loss ratio focuses on claims and claim adjustment expenses. Combined ratio adds underwriting expenses to show the broader insurance operating result.
Can combined ratio be calculated by policy or account?
It can be estimated, but small samples are volatile. The ratio is more reliable across credible portfolios, accident years, or mature segments.