The crust turns hard or dry when reheated or re-baked

Affects quality

A reheated crust turns hard after a long uncovered reheat, the microwave, fridge staling, or a pre-baked base given more time than the pack says.

Applies to: leftover pizza, takeaway or delivery pizza, premade or par-baked base, chilled supermarket pizza, frozen pizza

Ask yourself

How was it reheated — oven, microwave, air fryer or pan — and for how long?
Was it hard straight away, or soft at first and hard a few minutes later?
How was it stored — wrapped, or loose in the box in the fridge?
For a premade base or packaged pizza, did it get longer or hotter than the pack says?

Likely causes

#1
Reheated uncovered for a long time at moderate heat
Generally accepted
A slice already baked once has little moisture to spare. A long, uncovered reheat at moderate heat dries the crust and rim right through before the toppings are hot; covering for part of the reheat, or a covered pan, limits the loss.
#2
Microwave reheating
Generally accepted
A microwave heats the water in the crust; the slice comes out soft and steamy, then goes tough and leathery within minutes as it cools.
#3
Staling in the fridge that the reheat did not reverse
Generally accepted
Chilled crust firms mainly through starch retrogradation rather than drying, and fridge temperature speeds it up. Heating reverses much of it; a reheat that leaves the crust lukewarm leaves it stiff, and slices stored unwrapped also lose moisture.
#4
A pre-baked crust given extra time beyond the pack
Generally accepted
Premade bases and most frozen and chilled pizzas are already baked, and the pack's time is set to heat them through, not bake them again. Extra minutes to melt added cheese, or a hotter setting, dry the crust into a cracker.

Equipment-specific causes

The same symptom has different answers on different equipment. Each branch below states how to tell whether it is yours.

Bake environment

Pizza in an air fryerGenerally accepted
How you would know: A reheated slice came out of the air fryer with a crisp base but a hard, dry rim and over-browned edges.
Fast-moving hot air dries the exposed rim and edges of an already-baked slice quickly; by the time the toppings are hot the rim has lost most of its moisture.
Do now: Nothing restores a dried rim; eat it while warm, when it is at its least hard.
Change next time: Reheat at a moderate setting for a few minutes only, and add a little moisture first — a light film of water on the rim helps; a covered frying pan is gentler still for thick or bready crusts.
Pizza in a domestic ovenGenerally accepted
How you would know: Leftover slices reheated on a tray in a moderate oven for ten minutes or more came out hard and dry at the rim.
A long, uncovered reheat in a moderate oven dries the rim before the toppings are hot. The crust stiffened in the fridge mainly through starch retrogradation, which heat reverses; it is the extra time uncovered that does the damage.
Do now: Eat it while warm; a dried rim will not recover.
Change next time: Cover the slices with foil for most of the reheat and uncover for the last few minutes, or reheat in a covered frying pan with a few drops of water and uncover to crisp the base.

Rescue it now

Not reversible once dried, though a hard slice softens a little if eaten with something wet such as a dip; a crust that is stiff only from the fridge softens once heated properly through

Prevent it next time

Store slices wrapped or in a closed container, reheat in a covered pan (uncovering at the end to crisp the base) or covered for part of an oven reheat, avoid the microwave for crusts you want crisp, and keep premade and packaged pizzas to the pack's time, checking from the earliest time given

Cast iron pan

Go deeper

Guides that treat this as an outcome to improve, an environment to work with, or a flavour to understand, rather than only a problem to fix.

Pizza in a domestic oven Pizza in an air fryer