Mulch keeps soil moist, blocks weeds, and finishes a bed neatly.
About this calculator
Mulch keeps soil moist, blocks weeds, and finishes a bed neatly. Spread too thin and weeds break through in weeks. Buy too much and you are storing soggy bags until next season.
Enter bed length and width, mulch depth in centimetres (most guides suggest 5–10 cm), loose density (shredded bark is about 400 kg/m³), bag weight, wastage, and optional price. The calculator returns volume in cubic metres, weight, bags to order, and cost.
Keep mulch away from tree trunks — a volcano of bark against the bark causes rot. Refresh annually; colour fades but function remains. Large landscape jobs may use bulk cubic-metre delivery instead of bags. Pair with the [[gravel]] calculator for paths beside beds, the [[square-footage]] tool for irregular layouts, and the [[volume]] calculator when converting to bulk truck orders.
Common uses
- Planning bagged mulch for flower beds and shrub borders
- Estimating annual mulch refresh for a home garden
- Budgeting landscape material for a rental property
- Comparing bag price with bulk cubic-metre delivery
- Quoting mulch supply for a small gardening job
Frequently asked questions
How deep should mulch be?
Use 5 cm minimum for weed control. 8–10 cm works well around shrubs. Do not exceed 10 cm near plant stems or you risk suffocating roots.
Why does mulch density matter?
Bags are sold by weight but coverage is volumetric. Light shredded bark is far less dense than gravel. Wrong density skews bag count by double or more.
Will mulch settle?
Yes. Organic mulch can settle 20–30% in the first month. The 10% wastage buffer partly covers this; top up next season if beds look thin.
Can I use this for wood chips or compost?
Yes. Change density: compost ≈ 500–600 kg/m³ when moist; wood chips ≈ 350 kg/m³ loose. Depth recommendations differ — compost as soil amendment is often mixed, not piled deep.
How many bags cover 10 m²?
At 8 cm depth and 400 kg/m³, 10 m² needs 0.8 m³ ≈ 320 kg — about 13 bags of 25 kg before wastage. Run your exact bed size here for a precise count.