How much does it cost to insure your employees against workplace injuries? The workers' compensation premium is not a fixed figure: it depends on the total payroll, the riskiness of your business and your claims history. This calculator estimates it with the standard model: it takes the payroll, applies the rate of the risk class and the experience modification factor, and gives you the annual premium, the cost per employee and the premium as a percentage of payroll. It is the tool to understand the cost and what determines it.

What workers' comp insurance is

Workers' compensation insurance covers the medical expenses and lost income of employees who are injured or become ill because of work, while protecting the employer from lawsuits. In many countries (especially the US) it is mandatory for companies with employees, and the premium is borne by the employer. It is one of the most significant insurance cost items for businesses, especially in high-risk sectors: understanding how it is calculated helps to forecast and reduce it.

How the premium is calculated

The standard formula is: premium = (annual payroll / 100) × rate × experience mod. You start from the total payroll, divide it by 100 (because the rate is expressed per 100 of payroll), multiply by the rate of the risk class and finally by the experience modification factor. With a payroll of 500,000, a rate of 1.50 and a mod of 1.0: (500,000 / 100) × 1.50 × 1.0 = 7,500 of annual premium. It is a simple but powerful model: each factor has a clear role in the final cost.

The base: payroll and rate per 100

The base of the premium is the annual payroll: the higher it is, the higher the premium, because the risk exposure grows with the number and pay of the employees. The rate per 100 is the cost of the insurance for every 100 of payroll, and reflects the riskiness of the job. The base premium is therefore (payroll / 100) × rate: in the example, 5,000 × 1.50 = 7,500. It is the "manual" premium, before applying the company's specific experience mod.

The rate per risk class

The rate depends on the risk class of the job (class code): an office clerk has a very low rate (fractions per 100), a construction worker or a heavy-machinery operator a much higher rate (even several units per 100), because the probability and severity of injuries are greater. The rates are set by insurance or regulatory bodies by category and updated periodically. A company with multiple jobs has multiple class codes, each with its rate applied to the relevant share of payroll.

The experience modification factor (mod)

The experience modification factor (or "e-mod", "experience mod") is the factor that personalizes the premium based on your company's claims history compared to the sector average. A mod of 1.0 is the average: you pay the "manual" premium. A mod below 1.0 (e.g. 0.80) means you have had fewer claims than average: you get a discount (you pay 80%). A mod above 1.0 (e.g. 1.40) means more claims than average: you pay a surcharge (140%). It is the most important lever the company can control: improving safety reduces claims, lowers the mod and cuts the premium over the years.

Cost per employee and percentage of payroll

The calculator also provides the cost per employee (premium divided by the number of employees) and the premium as a percentage of payroll. With 7,500 of premium, 10 employees and 500,000 of payroll: 750 per employee and 1.5% of payroll. These two measures help to compare the cost between companies and sectors and to include it in the personnel budget: the workers' comp premium is effectively an additional labor cost, to be considered in the total cost of an employee besides salary and other contributions.

How the calculator works

Enter the total annual payroll, the rate per 100 of the risk class, the experience mod and the number of employees. The calculator returns the base premium, the annual premium with the experience mod, the cost per employee, the premium as a percentage of payroll and an assessment based on the mod. It is the quickest tool to estimate the cost of the injury insurance and understand how much the risk class and the claims experience weigh.

The values you need

You need four numbers. The total annual payroll of the covered employees. The rate per 100 of the risk class: you find it in the insurance quote or in the tables of the competent body for your category. The experience mod: if your company has one assigned (usually companies with a certain premium volume), use it; otherwise 1.0 (average). The number of employees, for the cost per employee. If you have multiple class codes, calculate each separately and sum the base premiums.

Interpreting the experience mod

The mod is the key indicator of your claims experience:

A high mod not only increases the premium, but also signals a safety problem to address: acting on claims is the only way to bring it back down over time.

What influences the premium

The workers' comp premium depends on three main levers:

Payroll and risk class are largely given; the experience mod is the lever the company can affect by improving safety and reducing claims.

Example: same payroll, different mods

With a payroll of 500,000 and a rate of 1.50 (base premium 7,500), how the premium changes as the mod varies:

The same payroll and the same rate can give very different premiums depending on the mod: the claims experience weighs directly on the cost, and the difference between a mod of 0.80 and one of 1.50 almost doubles the premium.

How to reduce the workers' comp premium

The premium can be reduced by acting on the controllable levers. The most important is to lower the experience mod by improving workplace safety: fewer injuries today mean a lower mod (and lower premiums) in the following years, because the mod is based on the history. Other levers: correctly classifying employees in the right class codes (avoiding higher rates than due), return-to-work programs to reduce the duration and cost of claims, and active claims management. Preventing a serious injury is worth much more than its direct cost, due to the multi-year effect on the mod.

What the calculation does not consider

The calculation is a simplified estimate of the base model. It assumes a single rate (one class code): companies with different jobs have multiple class codes, each with its rate applied to the relevant share of payroll. It does not include the additional elements of the real premium (issuance fees, insurance taxes and contributions, premium minimums, discounts for volume or advance payment, surcharges). The rules, rates and calculation of the experience mod vary a lot by jurisdiction and insurer. It is a starting point to estimate the order of magnitude: for the exact premium, request a quote.

Common mistakes

• Using gross payroll including items that some jurisdictions exclude (overtime above a threshold, specific bonuses).
• Applying a single rate when the company has multiple class codes with different risks.
• Ignoring the experience mod (or assuming 1.0 when the company has a different one).
• Forgetting taxes, fees and minimums that are added to the calculated premium.
• Not considering that reducing claims today lowers the premium for years via the mod.

How to use the calculator

Enter payroll, rate, experience mod and number of employees. Read the annual premium and the cost per employee for the budget. Look at the percentage of payroll to compare with sector benchmarks. Use the mod assessment to understand whether your claims experience is costing you dearly. Simulate different mods to quantify the value of improving safety. If you have multiple class codes, calculate each rate separately and sum. Remember that the real premium includes taxes and fees not calculated here: use the result as an estimate and request a quote for the exact cost.

Practical example

Your company has an annual payroll of 500,000, a risk-class rate of 1.50 per 100, an experience mod of 1.0 and 10 employees. The calculation gives a base premium of 7,500, an annual premium of 7,500 (neutral mod), a cost per employee of 750 and a premium of 1.5% of payroll, with the verdict "average: neutral mod". If you improved safety bringing the mod to 0.80, the premium would drop to 6,000, with a saving of 1,500 per year. Enter your numbers for your real situation. The calculation assumes a single rate and does not include taxes, fees, minimums and discounts or the specific rules of jurisdiction and insurer; the real experience mod is calculated by the competent body. It is an informational estimate, not a quote or insurance advice.

Frequently asked questions

What is workers' comp insurance?

It is workplace injury insurance: it covers medical expenses and lost income of employees who are injured or become ill because of work, and protects the employer from lawsuits. In many countries it is mandatory for companies with employees and the premium is borne by the employer.

How is the premium calculated?

Premium = (annual payroll / 100) × rate × experience mod. With a payroll of 500,000, a rate of 1.50 and a mod of 1.0: (500,000/100) × 1.50 × 1.0 = 7,500 per year. The rate is per 100 of payroll and depends on the risk class.

What is the experience modification factor?

It is the factor that adjusts the premium based on your company's claims history vs the average. Mod 1.0 = average (full premium); below 1.0 (e.g. 0.80) = discount for fewer claims; above 1.0 (e.g. 1.40) = surcharge for more claims. It is the main lever the company can control.

What is the rate per 100?

It is the cost of the insurance for every 100 of payroll, and depends on the risk class (class code) of the job. An office has low rates (fractions), construction or heavy work much higher rates, because injuries are more likely and severe.

What is a good experience mod?

Below 0.90 is excellent (strong discount), 0.90-1.0 good (discount), 1.0-1.05 average, 1.05-1.25 high (surcharge), above 1.25 very high. A high mod indicates too many claims and costs dearly: it should be brought down by improving safety, with a multi-year effect.

How can I reduce the premium?

The main lever is to lower the experience mod by improving workplace safety: fewer injuries today = lower mod and lower premiums over the years. Also: correctly classifying employees in the right class codes, return-to-work programs and active claims management.

Why is payroll the base of the premium?

Because the risk exposure grows with the number and pay of the employees: the more people work and the longer, the higher the cumulative probability of injuries. The rate is expressed per 100 of payroll precisely to tie the cost to the covered payroll.

What is the cost per employee?

It is the total premium divided by the number of employees: with 7,500 of premium and 10 employees, 750 each. It is useful for the personnel budget, because workers' comp is effectively an additional labor cost to consider besides salary and other contributions.

What happens if I have multiple different jobs?

Each job has a class code with its rate. You must apply the correct rate to the payroll share of each category and sum the base premiums. The calculator assumes a single rate: for a company with multiple class codes, calculate each separately.

Does the calculation include taxes and fees?

No, it calculates the "manual" premium base × mod. The real premium often includes insurance taxes and contributions, issuance fees, premium minimums, discounts and surcharges that vary by insurer and jurisdiction. Use the result as an estimate and request a quote for the exact cost.

Who assigns the experience mod?

Usually an insurance rating body or the competent authority, based on the company's claims and payroll data over a period (typically a few years). Companies below a certain premium threshold may not have an assigned mod and use 1.0. Verify your mod with the insurer.

Does workers' comp exist everywhere?

The concept of workplace injury insurance exists in many countries, but the model (rate per payroll, experience mod, mandatory nature, public or private management) varies a lot by jurisdiction. The rate × payroll × mod model is typical of the US; elsewhere the rules can differ.

Is it insurance advice?

No, it is an informational tool. It assumes a single rate, does not include taxes, fees, minimums and discounts or the specific rules of jurisdiction and insurer; the real experience mod is calculated by the competent body. For the exact premium request a quote and assess with a broker.

Updated July 2026