Landscape Volume Calculator
Every landscape job that involves loose material starts with the same question: how much do I need? This calculator answers it for a rectangular area from three measurements, the length and width in feet and the depth in inches, and returns the volume in cubic feet and cubic yards. That covers mulch for a flower bed, topsoil for a new lawn, gravel for a path, or compost for raised beds, because all of them are ordered by volume even though they weigh very different amounts.
This is the exact loose-fill volume for the dimensions entered. It does not add a settling or compaction allowance, and it does not convert to tons or bags; the tables below the calculator cover both.
Quick Answer
A bed 20 ft long by 5 ft wide filled 3 inches deep needs Volume: 25.00 ft³ or 0.93 yd³. That is the worked example pre-filled in the calculator: 20 × 5 × (3 ÷ 12) = 25 cubic feet, and 25 ÷ 27 = 0.93 cubic yards. Order it as 1 cubic yard in bulk, or about 13 bags at 2 cubic feet each.
Key takeaways
- Volume is length × width × depth, with depth converted from inches to feet (divide by 12) and cubic feet converted to cubic yards (divide by 27).
- One cubic yard covers 108 square feet at 3 inches deep, 162 at 2 inches, and 81 at 4 inches. Depth changes the order more than small measuring errors do.
- The tool reports the exact loose-fill volume only: no settling allowance, no tons, no bags. The tables on this page handle those conversions honestly.
- For several beds, run each one separately and add the cubic yards together, especially when depths differ.
- Quick Answer
- How to Use the Landscape Volume Calculator
- The Landscape Volume Formula
- Worked Example: a 20 by 5 Foot Bed at 3 Inches
- Coverage: What One Cubic Yard Actually Buys
- Choosing a Depth by Material
- Ordering: Settling, Weight, and Odd Shapes
- What Competing Calculators Miss
- Frequently Asked Questions
- Add This Calculator to Your Website
How to Use the Landscape Volume Calculator
Measure two sides in feet, choose a depth in inches, and click Calculate. The result stays hidden until you calculate.
- Enter the length: the longest side of the bed or area in feet, measured inside any edging. The worked example (20 ft) is pre-filled.
- Enter the width: the shorter side in feet. If the bed tapers, take two or three width readings and enter the average.
- Enter the depth in inches: inches, not feet. This is the single most common input mistake on volume tools, so the field is labelled in inches in the calculator itself: 3 for a normal mulch layer, not 0.25.
- Read the one-line result: cubic feet first, cubic yards second. Bulk suppliers quote yards; bag labels quote cubic feet, so both numbers earn their place. If you are planning the bed itself rather than filling it, the lawn area calculator covers area shapes beyond a plain rectangle.
Blank, zero, or negative entries return the message “Please enter valid positive numbers.” rather than a volume, because a bed with no depth needs no material and a negative depth is a measuring error, not a discount.
The Landscape Volume Formula
Volume (cubic feet) = Length (ft) × Width (ft) × Depth (in) ÷ 12, and Volume (cubic yards) = Volume (cubic feet) ÷ 27.
Volume (yd³) = Volume (ft³) ÷ 27
The two constants do unit work, nothing more. Dividing depth by 12 converts inches into feet so all three dimensions share a unit before they are multiplied. Dividing by 27 converts cubic feet into cubic yards, because a yard is 3 feet and 3 × 3 × 3 = 27. The method is the same one university extension services publish for mulch quantities, for example the Iowa State University Extension guide to determining mulch amounts, which multiplies bed area by depth in feet and divides by 27 for bulk orders. Material-specific volume tools use the identical core: the gravel volume calculator for stone and the fill volume calculator for grading fill.
Worked Example: a 20 by 5 Foot Bed at 3 Inches
A flower bed runs 20 feet along a fence and 5 feet out from it, and it is getting a fresh 3-inch mulch layer. The calculator is pre-filled with exactly these numbers.
Two more runs of the same tool, checked by hand, show how depth drives the order. The same bed at 2 inches needs 16.67 ft³ (0.62 yd³), and a 10 by 10 foot bed at 4 inches needs 33.33 ft³ (1.23 yd³). Doubling the depth doubles the material, while doubling one side only doubles it too: volume is unforgiving in every direction, which is why guessing by eye so often ends in a second trip to the supplier.
Coverage: What One Cubic Yard Actually Buys
One cubic yard covers a fixed area at a given depth, whatever the material. This table is the fastest sanity check on any calculator result, including this one.
| Depth | Area covered by 1 yd³ | 2 ft³ bags per yd³ | Typical use at this depth |
|---|---|---|---|
| 1 in | 324 sq ft | 13.5 | Compost top-dressing on a lawn |
| 2 in | 162 sq ft | 13.5 | Light mulch refresh; gravel path surface |
| 3 in | 108 sq ft | 13.5 | Standard new mulch bed |
| 4 in | 81 sq ft | 13.5 | Mulch around trees; topsoil for a new bed |
| 6 in | 54 sq ft | 13.5 | Topsoil for a new lawn; driveway gravel |
| 12 in | 27 sq ft | 13.5 | Raised bed fill |
The bag column is constant because it is pure unit conversion: 27 cubic feet divided by a 2-cubic-foot bag is 13.5 bags per yard, so round up to 14 bags per yard when you buy bagged. For the worked example, 25 cubic feet needs 12.5 bags, so 13 bags. Below about half a yard, bags usually win on convenience; beyond a yard, bulk delivery almost always wins on price and on trips.
Choosing a Depth by Material
The right depth depends on the material and the job, and it is the input with the most leverage: choosing 4 inches over 3 raises the order by a third. These are the working ranges landscapers and extension guides use.
| Material and job | Depth | Notes |
|---|---|---|
| Mulch, flower and shrub beds | 2 to 3 in | Suppresses weeds and holds moisture; refresh at 1 to 2 in |
| Mulch, around trees | 3 to 4 in | Keep it off the trunk flare; no mulch volcanoes |
| Topsoil, new lawn or bed | 4 to 6 in | Roots need depth; add a settling margin |
| Compost top-dressing | 0.5 to 1 in | Thin layer worked into lawns and beds |
| Gravel path or patio | 2 to 4 in | Over a compacted base; deeper layers shift underfoot |
| Gravel driveway | 4 to 6 in | Base plus surface courses combined |
Extension guidance puts mulch at 2 to 4 inches in most beds, with coarser materials at the deeper end and fine materials shallower, as Iowa State’s guide to using mulch in the garden sets out. Past 4 inches, mulch can shed rain instead of absorbing it and keep root zones waterlogged, so a deeper number in the calculator is not automatically a safer order.
Ordering: Settling, Weight, and Odd Shapes
The calculator returns exact geometric volume. Ordering well means adjusting that number for three real-world effects, each handled outside the tool on purpose, because none of them has one honest constant.
- Settling and compaction: soil, compost, and gravel finish lower than they are spread, typically by 10 to 15 percent after watering, rain, and traffic. Add that margin to the cubic yards before ordering those materials. Mulch being topped up to a visible depth needs little margin.
- Weight: volume is not weight. A cubic yard of dry mulch weighs a few hundred pounds; the same yard of gravel weighs roughly 2,700 pounds, and wet topsoil sits near the top of the range too. If a supplier sells by the ton, or a trailer or pickup has a payload limit, convert with the supplier’s own weight-per-yard figure for that material, not a generic table.
- Odd shapes: circles, triangles, and tapering beds do not fit a length-times-width box. Split the space into rough rectangles and add the runs, or compute the area another way and enter area as the length with 1 as the width. For genuinely irregular ground such as a pond basin, the lake volume calculator is built for that shape problem instead.
What Competing Calculators Miss
Volume tools for landscaping split into mulch-only specialists and general cubic-yard tools, and both camps leave gaps:
- Mulch specialists (CalculatePilot, Whiz Tools, Behrens): strong on bags, settling allowances, and per-material depth tables, and Behrens totals several beds at once. But the mulch framing hides the fact that the math is identical for topsoil, gravel, sand, and compost, and several bury the simple formula under product content.
- General cubic-yard tools (Cubic Yard Calculator and similar): handle any rectangular fill and add a waste percentage, but give no depth guidance at all, so a first-time gardener can order a flawless volume of mulch at a depth that smothers the bed.
- Soil and topsoil tools (Gardening Guider, TipCalculater, EverydayBudd): add bags, cost, weights, and waste factors. Useful extras, but the weight and cost figures rest on density and price assumptions that vary by supplier and moisture, presented as if they were properties of your project.
- The gap this page fills: one honest volume for any loose material, stated as exactly what it is (loose-fill geometry, no hidden allowances), surrounded by the reference material the others scatter: a coverage table audited against the formula, a depth-by-material table grounded in extension guidance, bag conversion, and plain disclosure of what the tool does not do (no tons, no settling factor, rectangles only) with the workaround for each.
Frequently Asked Questions
It works out how much loose material a rectangular area needs: mulch, topsoil, compost, gravel, sand or stone. Enter the length and width in feet and the depth in inches, and it returns the volume in cubic feet and cubic yards, the two units landscape materials are sold in.
Because landscape depths are small and are set in inches on site: 3 inches of mulch, 4 inches of topsoil. Entering depth in feet would mean typing decimals such as 0.25, which invites errors. The tool converts inches to feet for you by dividing by 12.
A cubic yard is a cube 3 feet by 3 feet by 3 feet, which is 27 cubic feet. It is the standard unit for bulk landscape material: one cubic yard of mulch spread 3 inches deep covers about 108 square feet.
It depends only on depth. One cubic yard covers about 324 square feet at 1 inch deep, 162 square feet at 2 inches, 108 square feet at 3 inches, 81 square feet at 4 inches and 54 square feet at 6 inches.
Not directly: the tool multiplies length by width, so it assumes a rectangle. For a round bed, work out the area with pi x radius squared, then treat that area as length x width by entering the area as the length and 1 as the width. For an irregular bed, split it into rough rectangles, run each one, and add the results.
No. It reports volume only, because weight per cubic yard varies too much by material and moisture to print one honest number: a yard of dry mulch weighs a few hundred pounds, while a yard of gravel can weigh around 2,700 pounds. If your supplier sells by the ton, ask them for the weight per yard of the actual material and divide your total weight by it, or give them the cubic yards and let their scale ticket settle it.
No. The result is the exact loose-fill volume for the dimensions entered. Soil and compost settle after watering and rain, and gravel compacts under traffic, so most landscapers order about 10 to 15 percent more than the calculated figure for those materials. Mulch in an existing bed needs less margin because you are topping up to a visible depth.
Yes, by adding. Run the calculator once per bed or area, note each cubic-yard figure, and add them together before ordering. Beds at different depths must be run separately, because depth is part of each calculation.
Mulch: 2 to 3 inches in flower beds and 3 to 4 inches around trees and shrubs, kept away from trunks. Topsoil: 4 to 6 inches for a new lawn or garden bed. Gravel: 2 to 4 inches for paths and 4 to 6 inches for a driveway base and surface combined. Deeper is not always better: mulch past 4 inches can keep roots too wet and shed water instead of absorbing it.
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References
- Iowa State University Extension and Outreach. How to Determine the Amount of Mulch Needed for a Garden Bed (area x depth in feet, divide by 27 for cubic yards, bags of 2 or 3 cubic feet). Accessed October 22, 2026.
- Iowa State University Extension and Outreach. Using Mulch in the Garden (mulch depths of 2 to 4 inches, coarse materials deeper, fine materials shallower). Accessed October 22, 2026.
- Clemson University Cooperative Extension, Home and Garden Information Center. Mulch (mulch types, depths, and keeping mulch away from trunks). Accessed October 22, 2026.
- National Institute of Standards and Technology. SI Units: Volume (litre and cubic measures and their relations). Accessed October 22, 2026.
- U.S. Environmental Protection Agency, WaterSense. WaterSense: Outdoors (mulch and landscape practices that reduce water use). Accessed October 22, 2026.