The length of time your cooler box will keep items cool can vary between a few hours and a few days depending on a number of factors. These include:
Insulation – some cooler boxes are better insulated than others so will keep contents cooler for longer.
Contents – packing lots of items inside your cooler will help them stay cooler for longer than if you only have a few.
Opening and closing – opening your cooler often will reduce the length of time it stays cool.
The temperature of items – pre-chilling your contents (and the cooler if possible) will help keep them cooler for longer.
Cooler packs – these are a great idea, especially if you end up with lots of spare room inside.