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Insurance Premium Pro Rata Calculator

Allocate a full-period insurance premium between the days used and the days remaining. This straight-line split excludes insurer charges and short-period rules, so it is not a cancellation refund quote.

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Your numbers

€
days
days
Your figures stay on this device.

How the calculation works

Pro-rata insurance arithmetic allocates a premium evenly across a supplied policy period. The result separates the amount attributable to days used from the unused portion, making the time allocation clear without interpreting cancellation terms or promising a refund.

Used premium = full premium × used days ÷ full-period days. Unused premium is the difference.

  1. Define one complete period

    Match the premium and day count to the same cover period. An annual price combined with a monthly day count would overstate the allocation.

  2. Find the used fraction

    Divide days used by full-period days. This expresses the share of the period being costed, from zero for no days to one for the complete period.

  3. Split the premium

    Multiply the premium by the used fraction. The unused pro-rata amount is the full premium less the used portion, so both parts reconcile before display rounding.

Worked example: Half period

Sample inputs demonstrate the method. They are not a forecast or product offer.

The first example allocates a €600 premium across 360 days, with 180 days used. Exactly half the period has elapsed, so €300 is attributed to cover used and €300 remains as the unused pro-rata portion. The 360-day input is deliberate, not an assumed calendar year.

Full-period premium (€)
600
Full policy period (days)
360
Days of cover used (days)
180

Expected result

Premium for days used
€300.00
Worked example: No days

Sample inputs demonstrate the method. They are not a forecast or product offer.

Full-period premium (€)
600
Full policy period (days)
365
Days of cover used (days)
0

Expected result

Premium for days used
€0.00

Understanding your result

The used premium is a straight-line allocation, not a measure of the insurer's actual risk or costs during those days. Equal numbers of days receive equal allocations in this model.

The unused portion is a useful reference amount when reviewing a cancellation statement. An actual refund may differ because of fees, short-period scales or other policy conditions that this tool does not apply.

Questions you might have

What does this insurance pro rata calculator include?

Calculate the straight-line premium attributable to part of a policy period using the premium and day counts you provide.

Which assumptions should I check?

A pro-rata amount is not a guaranteed cancellation refund. Insurer fees, short-period scales and policy conditions are excluded. Use the actual policy day count.

Choosing the right inputs

Full-period premium
Use the premium for the full period represented by the day count. Identify separately any fees or charges that do not follow a straight-line allocation.
Full policy period
Enter the actual number of days in that policy period rather than assuming every contract lasts 365 days.
Days of cover used
Count covered days on the same inclusion basis as the full period. Used days must not exceed the full-period count.

Common mistakes to avoid

  • Do not call the unused amount a confirmed cancellation refund.
  • Do not mix inclusive and exclusive date counting, which can shift the allocation by a day.

Assumptions to check

  • A pro-rata amount is not a guaranteed cancellation refund. Insurer fees, short-period scales and policy conditions are excluded. Use the actual policy day count.

Sources and method

Read our calculation and testing approach.