Mulch & gravel calculator
Find how much mulch, soil or gravel you need to fill a garden bed or path, by volume or bag count.
Fill in the fields and press Calculate to see your result here.
How this calculation works
Volume is length × width × depth, with depth converted from inches to feet first. The cubic-foot total converts to cubic yards (÷ 27, the usual unit for bulk delivery) and to standard 2-cubic-foot bags, a common size for bagged mulch and gravel.
Worked example
A flower bed 12 ft long and 4 ft wide, covered 3 inches deep: 12 × 4 × (3 ÷ 12) = 12 cubic feet, which is 0.44 cubic yards or about 6 bags at 2 cubic feet each.
Tips
Typical mulch depth is 2–4 inches
Too thin and weeds still get through; too thick (over 4 inches) can suffocate plant roots — most guides recommend 2–4 inches for mulch beds.
Buying in bulk is usually cheaper for larger areas
Once you need more than about 1 cubic yard, bulk delivery is often cheaper per unit than buying many bags.
Gravel is heavy
A cubic yard of gravel commonly weighs well over a tonne, so check delivery limits and ask your supplier for the exact weight.
Mulch settles
Mulch compacts and breaks down over the season. Plan to top it up about once a year.
Use edging or fabric
Landscape fabric and a firm edge stop gravel and mulch drifting into lawns and paths.
Frequently asked questions
Does this work for both mulch and gravel?
Yes — the calculation is a pure volume estimate, so it works for any bulk material sold by volume: mulch, soil, sand, or gravel.
How many bags come in a cubic yard?
A cubic yard is 27 cubic feet, so at 2 cubic feet per bag that's about 13–14 standard bags — this calculator does that conversion for you.