Common tiered structure: 24+ hours notice, no fee. 12-24 hours, 50% of session value. Under 12 hours or a no-show, 100% of session value. Adjust to your own policy, the key is writing it down and telling clients upfront, ideally in your contract or booking confirmation.
The calculator scales the cancellation fee based on notice given: cancellations with more advance notice cost less, since there's more time to fill the slot with other work; last-minute cancellations cost more, since the slot is effectively unrecoverable revenue.
This tiered structure is standard across service industries (photography, consulting, coaching, contracting) for exactly this reason: notice time is the real variable that determines how much revenue is actually lost.
A common structure: full refund or no fee for cancellations with 2+ weeks' notice, a partial fee (25-50%) for 3-14 days' notice, and the full fee for anything inside 72 hours or a no-show. The exact cutoffs should match how far in advance you typically book and how hard a slot is to refill.
A deposit is collected upfront and may be partially or fully applied toward a cancellation fee if the booking falls through; a cancellation fee can also be charged separately after the fact if no deposit was collected.
Most freelancers build in discretion to waive or reduce the fee for genuine emergencies while still charging it for simple scheduling changes, which keeps the policy fair without making it toothless.
Yes, always: stating it clearly in the contract or booking confirmation before the client commits is what makes charging it later feel fair rather than like a surprise penalty.