Understanding Expense Ratio
How we calculate. Expense ratio % = underwriting expenses ÷ earned premium × 100. See our methodology and accuracy policy .
Real-world scenario: A typical Expense Ratio case uses underwriting expenses 2800000 and earned premium 10000000. Enter the same figures below to reproduce the worked path.
What is Expense Ratio?
An efficiency KPI for distribution and underwriting ops. Some reports use written premium—label that variant clearly.
- Define expense inclusions
- Same period as earned premium
- Pairs with loss and combined ratios
The Formula
Worked Example
Common Use Cases
- Ops reviews: acquisition cost load
- Channel compare: agency vs direct
- COR build: expense component
Pro Tips
- Separate LAE if tracked elsewhere
- Watch commission seasonality
- Don’t mix GAAP and statutory blindly
| Scenario | When to use |
|---|---|
| Percent of a number | Finding a part of a whole (tax, tip, score) |
| Percent change | Comparing old vs new values |
Limitations: Expense Ratio results are educational insurance and agency planning aids—not underwriting, actuarial, claims, or financial advice. Confirm statutory definitions with your carrier, regulator, and finance teams.
Common mistakes
- Swapping part and whole: The denominator must be the full total, not a subset.
- Rounding too early: Carry extra decimal places through multi-step work before rounding the final percent.
- Mixing percent and decimal forms: Enter rates in the format the calculator labels expect.
The worked example for expense ratio was verified with the calculator form on this page—enter the same values to confirm the result.
When to use this calculator
- Use this page when your wording matches expense ratio and the form labels on screen.
- Use percent of a number for “what is X% of Y?” problems.
- Use number is what percent when you know part and whole and need the percent.
Still unsure about expense ratio? Start with the quick answer above, then open the linked calculator that matches your wording.
❓ Frequently Asked Questions
How do I use this expense ratio calculator?
For expense ratio, enter the values labeled on the form, then press Calculate. Compare the result to the worked example on this page.
What formula does this page use?
See the quick answer and formula box above for expense ratio—the same percentage calculator expression is applied to your inputs.
What if my result looks wrong?
When checking expense ratio, re-check part vs whole (or rate vs base), rounding, and whether percents were entered as 25 rather than 0.25 when the form expects percents.
Authoritative References
For insurance ratio and reporting concepts, consult:
- NAIC — U.S. insurance regulatory resources
- Casualty Actuarial Society — actuarial education resources
- Insurance Information Institute — industry explainers