Insurance Pro Rata Wheel Calculator
Calculation Summary
Total Days in Term:
Days Elapsed (Earned):
Days Remaining (Unearned):
Pro Rata Factor: %
Earned Premium: $
Unearned (Return) Premium: $
Understanding the Insurance Pro Rata Wheel Calculation
In the insurance industry, determining how much premium is "earned" by the carrier versus how much is "unearned" (and thus refundable to the policyholder) is a daily necessity. Historically, agents and underwriters used a physical "Pro Rata Wheel"—a circular sliding tool—to find the exact percentage of time elapsed between two dates. This digital Pro Rata Wheel Calculator replicates that logic with modern precision.
Pro Rata vs. Short Rate
A Pro Rata calculation is the most common method for determining premium adjustments. It assumes that the risk and cost of the policy are spread evenly across every day of the term. If a policy is canceled exactly halfway through its term, a pro-rata calculation returns exactly 50% of the premium. This is typically used when the insurance company cancels the policy or when endorsements are made mid-term.
In contrast, Short Rate cancellations (often used when the insured cancels a policy early) may include a penalty or administrative fee, meaning the return premium is less than the strictly proportional amount.
How to Use This Calculator
- Policy Effective Date: The date the insurance coverage officially began.
- Policy Expiration Date: The date the coverage was scheduled to end (typically one year later).
- Cancellation/Change Date: The date the policy is being canceled or adjusted.
- Total Policy Premium: The full cost of the policy for the entire term, excluding taxes or certain fees.
Step-by-Step Calculation Example
Imagine a business insurance policy with the following details:
- Term: January 1, 2023 to January 1, 2024 (365 days)
- Cancellation Date: April 1, 2023
- Total Premium: $1,000
1. Calculate Days Elapsed: From Jan 1 to April 1 is 90 days.
2. Calculate Factor: 90 days / 365 total days = 0.24657 (or 24.66%).
3. Calculate Earned Premium: $1,000 * 0.24657 = $246.57.
4. Calculate Unearned Premium: $1,000 – $246.57 = $753.43.
This calculator handles leap years and variable term lengths automatically to ensure your accounting and premium finance calculations are 100% accurate.