Prorated Subscription Calculator

About this calculator

This calculator works out a prorated charge as: (full period price ÷ total days in the billing cycle) × days remaining, so a customer only pays for the portion of the period they actually use rather than the full recurring price. If someone upgrades halfway through a 30-day billing cycle, this calculation charges them for roughly 15 days at the new rate instead of a full month.

Subscription businesses use proration whenever a customer changes plans mid-cycle, adds a seat partway through a billing period, or cancels early, and billing platforms like Stripe and Chargebee apply exactly this arithmetic under the hood to keep charges fair and dispute-free.