Ohio Workers’ Compensation Premium Calculator
Ohio employers don’t buy workers’ comp from an insurance company — they pay the Ohio Bureau of Workers’ Compensation (BWC). Your premium is basically your payroll, times your industry rate, adjusted by your own claims history. Enter the three numbers below to estimate your annual premium and see BWC’s payment plans.
How Ohio BWC is different
Ohio is one of only four monopolistic state-fund states: with a few exceptions (like very large self-insured employers), every Ohio employer must get workers’ compensation coverage from the state-run BWC — there is no private insurer to shop. The upside is one uniform system; the downside is your rate is what BWC assigns to your classification.
The formula is (payroll ÷ 100) × base rate × experience modifier. The base rate prices the risk of your industry; the experience modifier then rewards or penalizes your own claims record, which is why safety programs and prompt claims management literally lower next year’s premium. The minimum premium is $120 a year, and small employers at or near the minimum are billed in a single installment. BWC also adds administrative assessments to the manual premium on real bills — the amount varies, so treat this estimate as the core premium, not the final invoice.
Under BWC’s prospective billing, you pay based on estimated payroll, then complete a true-up report after the policy year ends: BWC compares estimated payroll with actual payroll and bills or credits the difference. Keep payroll records current during the year so the true-up isn’t a surprise.
BWC installment options
Private employers can spread premium over 1 (annual), 2 (semi-annual), 4 (quarterly), 6 (bi-monthly), or 12 (monthly) payments. Employers whose premium is over $250 default to the bi-monthly plan unless they choose another; premiums of $250 or less — and everyone at the $120 minimum — are billed as a single installment. The estimator above shows your premium under each plan.
The premium formula, piece by piece
Reportable payroll — your total Ohio payroll for the policy year, the base everything else multiplies. BWC’s reporting rules decide what counts; overtime, for example, is reported at straight-time value.
Base rate — BWC’s price per $100 of payroll for your manual classification (industry and job type). A roofing crew’s rate is many times an office’s — find yours in BWC’s employer rate lookup or on your policy page.
Experience modifier (EM) — your own claims history compared with similar employers. 1.00 is average; below 1.00 is a discount for a safer record, above 1.00 is a surcharge. New employers start at 1.00.
Minimum premium — $120 per year. If the formula produces less, the minimum applies instead, and the policy is billed in a single installment.
Administrative assessments — added by BWC on top of the manual premium on real bills. The amount varies, so this estimator leaves it out — expect the invoice to run slightly above the estimate.
A worked example. Take an employer with $500,000 of reportable payroll, a base rate of $2.50 per $100 of payroll, and an experience modifier of 1.00. The formula gives ($500,000 ÷ 100) × $2.50 × 1.00 = $12,500.00 in estimated annual premium. Paid through BWC’s installment plans, that is $12,500 once a year, $6,250 semi-annually, $3,125 quarterly, $2,083.33 bi-monthly, or $1,041.67 monthly. The same payroll with an EM of 0.90 instead of 1.00 would cut the premium by a tenth — which is why BWC’s structure rewards a cleaner claims record with a lower bill the following year.
How to use this estimator
- Find your base rate in BWC’s employer rate lookup at bwc.ohio.gov, or on the policy/certification page of your BWC account — it is set for your manual classification.
- Find your experience modifier on your BWC policy page. If you are a new employer with no claims history, use 1.00.
- Enter your annual reportable Ohio payroll — the figure from your last BWC true-up is the best starting point.
- Press “Estimate my premium” to see the annual premium, your effective rate per $100 of payroll, and what each BWC installment plan would charge per payment.
Frequently asked questions
How is Ohio workers’ comp premium calculated?
BWC’s formula is (payroll ÷ 100) × base rate × experience modifier. Your payroll is divided into $100 units, multiplied by the base rate BWC assigns to your manual classification, then adjusted up or down by your experience modifier. A $120 minimum premium applies if the result is lower, and BWC adds administrative assessments on the actual bill.
What are Ohio workers’ comp rates per $100 of payroll?
There is no single Ohio rate. BWC sets a separate base rate for every manual classification, and rates vary widely — low-risk office work is priced far below roofing or trucking. Your rate is the one in BWC’s employer rate lookup and on your policy page for your classification; this estimator uses the rate you enter rather than guessing one.
Can I buy workers’ comp from a private insurance company in Ohio?
Generally no. Ohio is a monopolistic state-fund state, so employers buy coverage from the state-run Bureau of Workers’ Compensation rather than a private insurer. The main exception is very large employers approved to self-insure.
What is BWC’s minimum premium?
$120 per year. If your computed premium comes out below that, you pay the minimum, and minimum-premium policies are billed in a single installment rather than spread across a payment plan.
What is the premium true-up?
Under prospective billing, BWC charges you during the policy year based on estimated payroll. After the year ends you file a true-up report of actual payroll; BWC then bills or credits the difference. Keeping payroll records current during the year keeps the true-up small.
Does this estimate match my final BWC bill exactly?
No — it estimates the manual premium from the three figures you enter. Real BWC bills add administrative assessments and reflect your exact classifications, payroll reporting rules, and any group-rating or discount programs you belong to, so the invoice typically runs slightly above the estimate.
Sources: Ohio Bureau of Workers’ Compensation — employer premium and prospective-billing guidance, policy EP-16-02 (installment plans) and BWC minimum-premium materials, bwc.ohio.gov. Verified October 31, 2026.
← All free Ohio tools from Stranfest.