How is Ohio workers' comp premium calculated?

Premium = (annual payroll ÷ 100) × base rate × experience modifier. The base rate is set per 100 dollars of payroll for each job classification, then adjusted by your company's experience modifier (EMR).

Does Ohio use private insurers or a state fund?

Ohio is a monopolistic state fund: most employers must buy workers' compensation coverage through the Ohio Bureau of Workers' Compensation (BWC), not private carriers. Self-insurance is allowed for qualifying large employers.

What is an experience modifier (EMR)?

The EMR compares your actual claim history to the expected average for your industry. A modifier of 1.0 is average; 0.85 means 15% below average (a discount), while 1.20 means 20% worse than average (a surcharge).

What is a typical base rate?

Base rates vary enormously by job risk — clerical office work may be under 0.20 dollars per 100 dollars of payroll, while roofing or trucking can exceed 8 to 12 dollars per 100. Always use your specific BWC classification rate.

Is this the final premium I will pay?

It is a close estimate. Ohio BWC also applies administrative costs, the DWRF assessment, and possible group-rating or deductible discounts, so your actual invoice may differ from this base calculation.

Ohio Workers' Compensation Premium Calculator

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Workers’ compensation is a mandatory cost for nearly every Ohio employer, and because Ohio runs a monopolistic state fund through the Bureau of Workers’ Compensation (BWC), the math is straightforward once you know three numbers. This calculator estimates your annual premium from payroll, your classification base rate, and your experience modifier.

How it works

The core Ohio BWC premium formula is:

Premium = (Annual Payroll ÷ 100) × Base Rate × Experience Modifier

Payroll per 100. Workers’ comp rates are quoted per $100 of payroll, so payroll is divided by 100 first.
Base rate. Each NCCI/manual classification code has its own base rate reflecting job risk — clerical staff are cheap, roofers and truckers are expensive.
Experience modifier (EMR). Multiplies the manual premium by your loss history. An EMR of 1.0 is average; 0.85 is a 15% credit; 1.20 is a 20% surcharge.

The result is your estimated annual manual premium before BWC administrative assessments and any group-rating discounts.

Tips and example

A landscaping crew with $300,000 in annual payroll, a base rate of $5.00 per $100, and an EMR of 1.0 would owe roughly (300000 ÷ 100) × 5.00 × 1.0 = $15,000 per year.

Improve your EMR by reducing claims and returning injured workers to light duty quickly — a drop from 1.20 to 0.90 cuts that same premium by 25%. Always confirm your exact classification and base rate with the Ohio BWC, since misclassification is the most common source of premium error.