Mulch Calculator
Estimate how much mulch you need for rectangular beds and circular tree rings. Compare bagged mulch with bulk cubic yards, add waste, and budget weight and cost.
Garden beds
Mulch depth guide
About the Mulch Calculator
The Mulch Calculator works out exactly how much mulch you need for any landscape project — flower beds, vegetable rows, foundation borders, playground surfaces, or tree rings. Enter your bed dimensions in feet (or metres) and the desired depth in inches (or centimetres), and the tool returns total volume in cubic yards, the number of standard bags to buy, the approximate weight, and the cost comparison between bulk delivery and bagged retail.
Choose from six common mulch types — bark mulch, wood chips, pine straw, cocoa hull, rubber mulch, and stone or gravel. Each preset updates the density used for weight estimation, because stone weighs roughly three times more per cubic foot than bark, and pine straw weighs less than half. Picking the right type matters when you need to know whether your hatchback can carry the load or whether you should arrange delivery.
Mix as many beds as you need — rectangular plots for borders and hedge rows, circular shapes for tree rings and round planters — and the calculator sums them into one combined order. A waste-and-settling slider compensates for the natural 10–20% compaction of fresh organic mulch and any uneven coverage on sloped ground.
How to Use the Mulch Calculator
- 1 Pick imperial or metric. Bed length and width use feet or metres; mulch depth uses inches or centimetres — the smallest unit that's natural for that dimension.
- 2 Choose your mulch type. Bark for general landscaping, wood chips for paths, pine straw for acid-loving plants, cocoa hull for fragrance, rubber for playgrounds, stone for permanent borders. The density (used for weight) updates automatically.
- 3 Add each bed. Rectangular beds need length and width; tree rings and round planters use diameter. Add as many as you need with the "Add another bed" button. Each row shows its own area and volume as you type.
- 4 Set the depth. 1–2 inches to refresh existing mulch, 2–3 inches for new flower beds, 3–4 inches for weed suppression. Stone or rubber installs are usually 2–3 inches.
- 5 Adjust waste / settling. 10% is a sensible default for organic mulch. Drop to 5% for stone, push up to 15–20% for very loose mulch on sloped ground.
- 6 Compare cost. Enter your local bag size, bag price, and bulk price per cubic yard (or per cubic metre). The "Best value" badge highlights the cheaper option and shows your savings.
Frequently Asked Questions
How deep should mulch be? ▾
It depends on the bed and the goal:
- Refreshing existing mulch: 1–2" (2.5–5 cm)
- New flower beds & vegetable rows: 2–3" (5–7.5 cm)
- Weed suppression in shrub borders: 3–4" (7.5–10 cm)
- Playground rubber mulch: 4–6" (10–15 cm)
- Decorative stone / gravel: 2–3" (5–7.5 cm)
Avoid going past 4" of organic mulch around plant stems — it traps moisture against the bark and can cause rot ("volcano mulching" around trees is a common mistake).
How many bags of mulch are in a cubic yard? ▾
A cubic yard is 27 cubic feet, so it equals about 13.5 standard 2-ft³ bags or 9 large 3-ft³ bags. In metric, one cubic metre ≈ 1,000 litres ≈ 20 × 50 L bags. The calculator rounds up to whole bags automatically.
Which mulch type lasts the longest? ▾
Stone is effectively permanent. Rubber lasts 10+ years. Among organic options, wood chips (especially hardwood) last 2–4 years, bark 1–2 years, and pine straw and cocoa hull typically need replacing every season. Longer-lasting mulches save money over time but don't add organic matter to the soil — pick based on whether you want low maintenance or soil improvement.
Bags or bulk — which should I order? ▾
Bulk delivery is roughly half the cost per cubic yard but needs space for a tipper truck to dump it and a wheelbarrow to move it. Crossover is around ½ cubic yard (≈ 7 standard bags): below that, bags are easier; above it, bulk saves real money. The calculator's "Best value" badge picks the cheaper option for your project after you enter both prices.
How often should I refresh mulch? ▾
Organic mulch breaks down and thins out each season. A general schedule: top up bark and wood chips every 1–2 years (1–2" added), replace pine straw and cocoa hull annually, fluff and re-edge stone borders annually but only replace when settled into the soil. Spring is the most common time, just after weed pre-emergent application.
Can I put fresh mulch over old mulch? ▾
Yes — but only if the existing mulch layer is under 2" deep and the total combined depth stays under 4". Otherwise rake out the old layer first. Mulch piled too thick suffocates roots, harbours pests, and can form a water-shedding crust on the surface that keeps rain from reaching the soil below.
Is my data saved or sent anywhere? ▾
No. The calculator runs entirely in your browser — bed dimensions, prices, and mulch choices never leave your device and nothing is stored on a server.