Public Liability Insurance Calculator

Public liability cover responds to third-party claims: someone who is not on your payroll is injured, or their property is damaged, and your business activity is what caused it. IRMI's glossary defines it as liability to third parties for causing bodily injury or property damage. Insurers rarely start from your trade name. They start from an exposure base, most often revenue, receipts or payroll, then apply a rate to it. This calculator uses annual turnover as that base, which is how most small-business liability policies are rated, then scales the answer by the cover limit and a risk multiplier you set.

Quick example

With annual turnover of 100,000 and a cover limit of 2,000,000 at a risk factor of 1, the result is 500.00 a year, or 41.67 a month.

Which inputs matter most

You enter Annual Turnover, Coverage Limit, and Risk Factor (0.5 low, 1 medium, 2 high). Every figure is in whichever currency you pick at the top of the calculator, so the maths behaves identically whether you trade in dollars, euros, pounds or rupees.

The rate the model applies

The base rate is 0.5% of turnover, defined at a reference limit of 2,000,000 and a risk factor of 1. Cover is normalised against that reference, so 5,000,000 of cover multiplies the base by 2.5, and the risk factor multiplies whatever is left. At the reference limit that arithmetic lands on 0.25% of turnover at risk factor 0.5, 0.50% at 1.0 and 1.00% at 2.0. Those are the model's own numbers, not a market survey. Published rates move with trade, territory, claims record and how hungry an insurer is for that class of business, so the percentage shown on screen is a planning figure rather than a benchmark.

Worked example: a plumbing contractor

A plumbing firm turning over 250,000 a year needs 5,000,000 of cover to satisfy a site contract, and sits at the medium risk factor of 1.0.

1. Base premium: 250,000 × 0.5% = 1,250
2. Coverage adjustment: 5,000,000 ÷ 2,000,000 = 2.5
3. Risk adjustment: risk factor 1.0
4. Estimated annual premium: 1,250 × 2.5 × 1.0 = 3,125

Push that firm to the 10,000,000 limit some principal contractors ask for and the estimate doubles to 6,250. Leave the limit alone but reclassify the work as high risk at 2.0 and it also lands on 6,250, because both levers are linear. Grow turnover 20% to 300,000 with everything else held still and the premium moves the same 20%, to 3,750. That linearity is the model's main simplification: real rating tables usually flatten out as limits climb, because the second million of cover is less likely to be claimed than the first.

Where the estimate stops being useful

Claims history, the excess or deductible on the policy, underwriting judgement, broker commission, insurance premium taxes and levies are all outside this calculation. Minimum premiums are the sharpest edge. A side business turning over 5,000 computes to 25 a year here, and no insurer writes a liability policy at that price, so anything under a few thousand of turnover reads as a floor rather than a quote. The output is an educational illustration of how three variables interact. Broker quotes remain the only way to see what a specific business would actually be charged.