Insurance Premium Proration Calculator

About this calculator

Insurance premiums are usually quoted as an annual figure, but coverage often starts or ends partway through the year — a policy canceled early, a new policy added mid-term, or coverage that only needs to run for a few months. Proration handles this by charging only for the fraction of the year the coverage is actually in force: prorated premium = annual premium × (days of coverage ÷ days in the year).

This calculator applies that pro-rata math for you, taking an annual premium and a coverage period and returning the fair partial-term amount. It's the same logic insurers and brokers use to calculate refunds on early cancellations, charges for mid-term policy changes, or the premium for a short-term or interim policy — useful for anyone checking that a prorated bill or refund lines up with what they should actually owe.