Workers' Compensation Premium Calculator — Rex's Toolbox

Rex says

Money math without the spreadsheet headache. Plug in your numbers and I'll show you exactly where the dollars land.

Try a scenario

Click to load — tweak from there.

Inputs

Class 1 payroll($)

Class 1 rate per $100 payroll($)

Class 2 payroll($)

Class 2 rate per $100 payroll($)

Class 3 payroll($)

Class 3 rate per $100 payroll($)

Experience modification factor(×)

Scheduled / premium discount(%)

Expense constant($)

Result

Estimated annual premium

$19,174

Per month

$1,598

Manual premium before mod

$19,920

After experience modifier

$19,920

Premium as share of payroll

4.57%

Saving per 0.10 mod improvement

$1,892

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How to use this

1Enter class 1 payroll ($).
2Enter class 1 rate per $100 payroll ($).
3Enter class 2 payroll ($).
4Enter class 2 rate per $100 payroll ($).
5Enter class 3 payroll ($).
6Enter class 3 rate per $100 payroll ($).
7Enter experience modification factor (×).
8Enter scheduled / premium discount (%).
9Enter expense constant ($).
10Read your estimated annual premium on the right — it updates as you type.
11Hit Share to keep the scenario or send it to someone.

About this calculator

Workers' compensation premium is one of the few insurance costs with a transparent formula: payroll per hundred dollars, multiplied by a class code rate published for your state, multiplied by your experience modification factor, then adjusted by carrier-specific discounts and expense constants. This calculator runs that formula for up to three payroll classes so a business with office staff and field crews can see how the mix drives the bill. The experience modifier is the lever most owners underuse — it compares your claim history to the average for your class, so a mod of 0.85 cuts 15% off the manual premium while a 1.25 adds a quarter, and it follows the business for three years. The output also shows premium as a share of payroll and the annual saving from moving the mod down by a tenth, which is usually the clearest way to justify spending on safety programmes and prompt claim management.

FormulaPremium = Σ (Payroll ÷ 100 × Class Rate) × Experience Mod × (1 − Discount) + Expense Constant.

Worked example

Using the values the calculator loads with:

Inputs

Class 1 payroll: 300000 $
Class 1 rate per $100 payroll: 6.5 $
Class 2 payroll: 120000 $
Class 2 rate per $100 payroll: 0.35 $
Class 3 payroll: 0 $
Class 3 rate per $100 payroll: 0 $
Experience modification factor: 1 ×
Scheduled / premium discount: 5 %
Expense constant: 250 $

Results

Estimated annual premium: $19,174
Per month: $1,598
Manual premium before mod: $19,920
After experience modifier: $19,920
Premium as share of payroll: 4.57%
Saving per 0.10 mod improvement: $1,892

What each field means

Inputs

Class 1 payroll ($): The class 1 payroll used in the calculation, measured in $. Starts at 300000 $ so you have a working example on load. Accepted range: 0–20000000 $.
Class 1 rate per $100 payroll ($): The class 1 rate per $100 payroll used in the calculation, measured in $. Starts at 6.5 $ so you have a working example on load. Accepted range: 0.05–60 $.
Class 2 payroll ($): The class 2 payroll used in the calculation, measured in $. Starts at 120000 $ so you have a working example on load. Accepted range: 0–20000000 $.
Class 2 rate per $100 payroll ($): The class 2 rate per $100 payroll used in the calculation, measured in $. Starts at 0.35 $ so you have a working example on load. Accepted range: 0–60 $.
Class 3 payroll ($): The class 3 payroll used in the calculation, measured in $. Starts at 0 $ so you have a working example on load. Accepted range: 0–20000000 $.
Class 3 rate per $100 payroll ($): The class 3 rate per $100 payroll used in the calculation, measured in $. Starts at 0 $ so you have a working example on load. Accepted range: 0–60 $.
Experience modification factor (×): The experience modification factor used in the calculation, measured in ×. Starts at 1 × so you have a working example on load. Accepted range: 0.5–2 ×.
Scheduled / premium discount (%): The scheduled / premium discount used in the calculation, measured in %. Starts at 5 % so you have a working example on load. Accepted range: 0–40 %.
Expense constant ($): The expense constant used in the calculation, measured in $. Starts at 250 $ so you have a working example on load. Accepted range: 0–2000 $.

Results

Estimated annual premium: Returned as a money amount in US dollars and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
Per month: Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
Manual premium before mod: Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
After experience modifier: Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
Premium as share of payroll: Returned as a percentage. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
Saving per 0.10 mod improvement: Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.

FAQ

Where do I find my class code rate?

State rating bureaus (or NCCI in most states) publish loss costs by class code, and your carrier applies its own multiplier. Your policy declarations page lists the codes and rates currently applied to your payroll.

How is the experience mod calculated?

It compares your actual losses over a three-year window against expected losses for your payroll and class. Frequency of small claims hurts more than a single large one in most formulas, which is why prompt return-to-work programmes pay off.

Do owners and officers count in payroll?

It depends on the state and entity type. Many states let owners exclude themselves, and most cap included officer payroll at a statutory maximum. Excluding yourself can cut premium substantially but removes your own coverage.

Is overtime included at full value?

Usually only the straight-time portion of overtime counts, so paying overtime is often cheaper than the raw payroll figure suggests. Ask your auditor how they treat it before the year-end audit.

Accuracy and limitations

Results are estimates before tax, fees, and inflation unless an input explicitly covers them.
Rates are treated as fixed for the whole period — variable-rate products will drift from this projection.
This is educational maths, not financial advice. Check anything contractual with the lender or your accountant.

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Cite this calculator

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APA

RevenueLab. (2026). Workers Comp Premium Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/workers-comp-premium-calculator

HTML

<p>Source: <a href="https://www.revenuelab.fyi/toolbox/workers-comp-premium-calculator" target="_blank" rel="noopener">Workers Comp Premium Calculator — RevenueLab</a> (2026).</p>

Markdown

Source: [Workers Comp Premium Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/workers-comp-premium-calculator) (2026).