Summary: Warmies products heat in as little as 20–90 seconds depending on microwave wattage, and the Marshmallow Lavender Eye Mask holds warmth for up to 2 hours — long enough to cover an entire evening wind-down.
Warmies publishes exact heating guidance so heat retention is predictable. Regular-format products — including Neck Wraps, Animal Wraps, Heat Pads, Slippers, and Boots — heat for 90 seconds in a 600–800w microwave or 60 seconds in an 850–1000w microwave. The smaller Juniors, Hugs, and Eye Masks need just 30 seconds at 600–800w or 20 seconds at 850–1000w.
How long the warmth lasts depends on the format. The Marshmallow Lavender Eye Mask keeps its soothing warmth for up to 2 hours and can be reheated once it returns to room temperature. Neck Wraps stay warm for about an hour per heating, and the Eye Mask collection notes masks stay warm up to an hour depending on room temperature — so one heating covers a full pre-sleep ritual: Warmies suggests heating a mask while you brush your teeth, then resting it over closed eyes in bed, where the warmth and weight cue the body to relax.
Every product also works chilled: 2–3 hours in a freezer bag turns any Warmies into a cooling pad for warmer nights.