Mulch Calculator
This free mulch calculator tells you exactly how much mulch to buy for any bed. Enter the length, width, and depth and you get the volume in cubic yards, cubic feet, and standard 2-cubic-foot bags – so you order the right amount the first time.
How much mulch do you need?
How the mulch calculator works
The mulch calculator turns three quick measurements into the amount you actually buy. It multiplies the bed length by the width to get the area in square feet, multiplies that by the depth (converted from inches to feet), and divides by 27 to convert cubic feet into cubic yards – the unit bulk suppliers use. The same volume is also shown in cubic feet and as the number of standard 2-cubic-foot bags, so you can compare bagged and bulk pricing at a glance.
The shortcut version of the formula is: square feet × depth in inches ÷ 324 = cubic yards. For most landscape beds a depth of 2 to 3 inches is ideal – deep enough to block weeds and hold moisture, without smothering plant roots. Coarser bark mulches can go up to 4 inches, while a light refresh of existing mulch only needs an inch or two.
Worked example
Say you have a 20 ft by 10 ft bed and you want 3 inches of mulch. That is 200 square feet × 0.25 ft = 50 cubic feet, or about 1.85 cubic yards. In bags, 50 ÷ 2 = 25 bags of the common 2-cubic-foot size. Because mulch settles and beds are rarely perfectly square, adding roughly 10% means ordering 2 cubic yards or about 28 bags to be safe.
Bags vs. bulk: how much mulch to buy
Bagged mulch is convenient and easy to haul in a car, and it makes sense for small beds or when you need different colors in different spots. Bulk mulch, sold by the cubic yard and delivered by truck, is almost always cheaper per yard once you pass roughly 3 cubic yards. One cubic yard equals 27 cubic feet, or about 13.5 of the standard 2-cubic-foot bags.
For depth guidance and mulching best practices, see the Mississippi State University Extension mulch guide and the University of Florida IFAS Extension, both of which recommend keeping mulch a few inches back from stems and trunks to prevent rot.
Frequently asked questions
How much mulch do I need for my garden?
Measure each bed’s length and width in feet, pick a depth (2-3 inches is typical), and the calculator returns cubic yards, cubic feet, and bag count. As a rule of thumb, one cubic yard covers about 108 square feet at 3 inches deep.
How many bags of mulch are in a cubic yard?
A cubic yard is 27 cubic feet, so it equals about 13.5 bags of the standard 2-cubic-foot size, 18 bags of 1.5 cubic feet, or 27 bags of 1 cubic foot. Always check the bag’s stated cubic footage before buying.
How deep should mulch be?
Two to three inches suits most flower and shrub beds. Use up to four inches of coarse bark for heavy weed suppression, and only one to two inches when refreshing mulch that is already in place.
Is bagged or bulk mulch cheaper?
Bulk mulch is usually cheaper per cubic yard and the better choice above about 3 cubic yards, especially since delivery is often included on larger orders. Bags win for small jobs and easy handling.
Should I order extra mulch?
Yes. Mulch settles and compresses, and beds have uneven edges, so adding about 10% and rounding up avoids running short mid-project and paying for a second trip or delivery.