MulchCalc
How Much

How Much Mulch Do I Need?

The honest answer takes four steps: measure, set depth, multiply, and convert. Skipping the depth choice or unit conversion is a common source of ordering errors. Below is the general procedure, with the bag and bulk math worked out so you can stop guessing.
A person in dark canvas work pants standing back from a freshly mulched front yard with mixed beds, hand on hip, surveying the work.
Photograph for MulchCalc.
The worksheet

Do the
math here.

Enter dimensions in the units you measured in. The page does the converting — cubic feet, cubic yards, bag counts, and price — without sending your numbers anywhere.

The 4-step universal procedure

Last updated 2026
  1. Step 1 — Measure the area in sq ft. Rectangle: length × width. Circle: π × radius² (or 0.7854 × diameter²). Triangle: ½ × base × height. Irregular: divide into rectangles and triangles, sum the parts.
  2. Step 2 — Pick a depth and convert to feet. Inches ÷ 12 = feet. Garden depth depends on material, plants, and site guidance. For playground surfacing, use the exact product's ASTM F1292 critical-fall-height report and tested installation depth rather than a generic preset.
  3. Step 3 — Multiply for cubic feet. Area (sq ft) × depth (ft) = volume (cu ft). A 100 sq ft bed at 3" = 100 × 0.25 = 25 cu ft.
  4. Step 4 — Convert to bags or yards. Cubic yards: cu ft ÷ 27. 2 cu ft bags: cu ft ÷ 2. 3 cu ft bags: cu ft ÷ 3. Add 10% settling buffer and round up.

Quick-reference: mulch needed for common bed sizes

Bed sizeSq ftCu yd @ 3″2 cu ft bags3 cu ft bags
4 × 8 raised bed320.3353
10 × 10 island1001.031410
6 ft tree ring280.34 @ 4″54
3 × 30 foundation strip900.92139
15 × 25 front yard3753.825235
1,000 sq ft full landscape1,00010.213892

Two worked examples — bag and bulk

The four mistakes we see most often

  • Skipping the unit conversion. Multiplying area (sq ft) by depth in inches produces a result 12× too large. Always convert depth to feet first.
  • Eyeballing bed size. A tape measure is much more accurate than eyeballing. Measure each dimension and repeat the reading where the edge is irregular.
  • Confusing bag sizes. 2 cu ft is the US default; 3 cu ft bags are 50% larger but visually similar. Always confirm the cubic-foot label before doing math.
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Frequently asked questions

How much mulch for a typical front yard?+

Most US suburban front yards carry 400–800 sq ft of mulched beds (tree rings, foundation strips, one or two islands). At 3-inch depth that is 3.7–7.4 cu yd — one bulk delivery for the whole yard, or roughly 50–100 bags of 2 cu ft.

How many bags for a 100 sq ft bed?+

At 3-inch depth: 100 × 0.25 = 25 cu ft = 12.5 bags of 2 cu ft. Round up to 14 with the settling buffer. Or 9 bags of 3 cu ft. Or one bulk cubic yard with a few cubic feet left over for top-up next month.

How much mulch for a tree ring?+

A 6 ft diameter ring is 28 sq ft. At ANSI A300's 4-inch depth (donut shape, tapered to 1 inch at trunk): 9.4 cu ft = 5 bags of 2 cu ft. An 8 ft ring at the same depth: 17 cu ft = 9 bags.

Is it better to over-order or under-order?+

Over-order by 10%. The marginal cost of one extra 2 cu ft bag is about $4.50; the cost of a second store trip is $8–$15 in gas and roughly 45 minutes of your day. Extra mulch keeps fine outdoors covered with a tarp until the next refresh.

How do I estimate without measuring?+

Pacing gives a rough estimate. For the final order, measure each dimension with a tape, especially on uneven ground.

Does the math change for non-rectangular beds?+

Only step 1 changes. Use π × r² for circles, ½ × base × height for triangles, and 0.785 × length × width for ovals. For freeform islands, divide into 2–3 simpler shapes, find each area, then sum. Steps 2–4 stay identical.

What if my supplier sells by liter or kilo?+

Multiply cu ft by 28.3 to get liters. Most metric markets (UK, EU, AU) sell mulch in 50, 70, or 80 liter bags. For weight, dry hardwood averages 12–15 kg per 50 L bag — useful for trunk-load planning.

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