Deck boxes are sold by gallons, sheds and cabinets by cubic feet, and neither number tells you whether your longest cushion will fit. The most reliable way to size outdoor storage is to measure what you plan to put in it and compare that with the interior dimensions the maker lists.

This guide explains how to measure, how gallons and cubic feet compare, and which type of storage suits which items. For picks, see Best Deck Boxes and Best Small Deck Boxes.

Measure What You Will Store

Lay out the items you want to store, such as seat and back cushions, pool floats or tools. Measure the longest item and the height of a stack of cushions. Length is usually the limiting factor, because a box can have plenty of volume and still be too short for a chaise cushion.

Gallons and Cubic Feet

One cubic foot equals about 7.48 US gallons, so a 150 gallon deck box holds roughly 20 cubic feet. That helps when comparing a deck box with a storage cabinet listed in cubic feet. Makers measure capacity differently, though, and some quote outside rather than inside volume, so use these numbers as a rough guide only.

Use Interior Dimensions

Where a maker lists interior dimensions, compare them with your measurements. Lifetime, for example, lists both the outside and inside size of its 130 gallon box. If only outside dimensions are given, allow for the wall thickness and the lid.

Match the Type to the Job

Check the Space Too

Measure where the storage will sit, including room for the lid or doors to open fully. Keep walkways, doors and gates clear, and on a balcony, check your building's rules.

FAQ

How many gallons is a large deck box?

Large resin deck boxes in our guides are often 100 to 150 gallons, and some metal boxes reach 200 gallons.

Is a bigger deck box always better?

No. A box that is too large takes up seating space. Size it to what you store, with some room to spare.

How do I convert gallons to cubic feet?

Divide gallons by about 7.48. A 150 gallon box is roughly 20 cubic feet.

The Bottom Line

Measure your longest item first, compare it with the interior dimensions, and use gallons and cubic feet only as a rough comparison. Then choose the type of storage that fits the job and the space. Browse the Deck Boxes & Outdoor Storage category for all our picks.