Pro Rata Wheel Calculator Insurance

Pro Rata Insurance Wheel Calculator

Calculation Summary

Days in Period: 0
Pro Rata Factor: 0.0000
Earned Premium: $0.00
Unearned Premium: $0.00

What is a Pro Rata Insurance Wheel?

In the insurance industry, a "Pro Rata Wheel" was traditionally a physical circular slide rule used by underwriters and agents to quickly determine the decimal factor used to calculate earned and unearned premiums. When a policy is cancelled mid-term, the insurance company must determine how much of the premium they have "earned" based on the time the policy was active and how much must be returned to the policyholder ("unearned").

Understanding the Calculation Logic

Unlike "Short Rate" cancellations, which apply a penalty for early termination, a Pro Rata calculation is a straight mathematical ratio based on time. The formula used by this digital wheel is:

  • Days Elapsed: The number of calendar days between the effective date and the cancellation date.
  • Pro Rata Factor: Days Elapsed / 365 (or 366 in leap years).
  • Earned Premium: Total Premium × Pro Rata Factor.
  • Unearned Premium (Refund): Total Premium – Earned Premium.

Practical Example

If you have an annual auto insurance policy that costs $1,200 and you cancel it exactly 73 days into the term:

  1. The Pro Rata Factor is 73 / 365 = 0.20.
  2. The Earned Premium is $1,200 × 0.20 = $240.
  3. The Unearned Premium (your refund) is $1,200 – $240 = $960.

When to Use This Calculator

This tool is essential for insurance professionals and policyholders during mid-term adjustments, cancellations, or when verifying the accuracy of a refund check. It provides the "wheel factor" down to four decimal places, ensuring precision in financial reconciliation.

function calculateProRata() { var startInput = document.getElementById("startDate").value; var endInput = document.getElementById("endDate").value; var premium = parseFloat(document.getElementById("premiumAmount").value); var errorDiv = document.getElementById("errorArea"); var resultsDiv = document.getElementById("resultsArea"); // Reset displays errorDiv.style.display = "none"; resultsDiv.style.display = "none"; // Validate inputs if (!startInput || !endInput || isNaN(premium)) { errorDiv.innerHTML = "Please provide valid dates and premium amount."; errorDiv.style.display = "block"; return; } var date1 = new Date(startInput); var date2 = new Date(endInput); // Basic date logic if (date2 1) { factor = 1; } // Cannot earn more than 100% var earned = premium * factor; var unearned = premium – earned; // Format results document.getElementById("daysDisplay").innerHTML = dayDiff; document.getElementById("factorDisplay").innerHTML = factor.toFixed(4); document.getElementById("earnedDisplay").innerHTML = "$" + earned.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2}); document.getElementById("unearnedDisplay").innerHTML = "$" + unearned.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2}); resultsDiv.style.display = "block"; }

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