Last updated: May 30, 2026
Soil Calculator
Creators
Dharmendra SinghReviewers
Creators
Dharmendra SinghReviewers
Quick Answer
The Soil Calculator estimates how much soil is needed to fill a garden bed or planter. It multiplies length × width × (depth ÷ 12) for cubic feet, divides by 27 for cubic yards, and converts to bags and an estimated bulk cost. A 9 × 6 ft bed 6 inches deep needs 27 ft³ = 1 cubic yard.
To find how much soil you need, multiply the bed length by width in feet, then by the depth in feet (inches divided by 12). That gives cubic feet; divide by 27 for cubic yards. A 9 by 6 foot bed 6 inches deep needs 27 cubic feet, which is one cubic yard.
Key Takeaways
- Soil volume = length × width × (depth ÷ 12) in cubic feet; divide by 27 for cubic yards
- A 9 × 6 ft bed filled 6 inches deep needs exactly 1 cubic yard (27 ft³)
- 1 cubic yard = 27 ft³ ≈ 18 bags of 1.5 ft³ or 13.5 bags of 2 ft³
- Buy bulk soil once you need about a cubic yard or more to save money
- Order ~10% extra to allow for settling and compaction
Creators
Dharmendra SinghReviewers
Creators
Dharmendra SinghReviewers
Formula
Cubic Feet = Length × Width × (Depth ÷ 12); Cubic Yards = Cubic Feet ÷ 27
Where:
- V_{ft^3}=Soil volume in cubic feet(ft³)
- L \times W=Bed length and width(ft)
- D=Target soil depth(in)
- 27=Cubic feet per cubic yard(ft³/yd³)
Worked Examples
Standard Raised Bed (9 x 6 ft, 6 in deep)
A classic raised garden bed filled to 6 inches, priced at $40 per cubic yard.
- 1Convert depth: 6 in ÷ 12 = 0.5 ft
- 2Cubic feet = 9 x 6 x 0.5 = 27 ft³
- 3Cubic yards = 27 ÷ 27 = 1 yd³
- 4Bags (1.5 ft³) = 27 ÷ 1.5 = 18 bags
- 5Cost = 1 yd³ x $40 = $40
Deep Veggie Bed (10 x 4 ft, 12 in deep)
A deep bed for root vegetables, ordered in 2 ft³ bags.
- 1Convert depth: 12 in ÷ 12 = 1 ft
- 2Cubic feet = 10 x 4 x 1 = 40 ft³
- 3Cubic yards = 40 ÷ 27 = 1.48 yd³
- 4Bags (2 ft³) = 40 ÷ 2 = 20 bags
- 5Cost = 1.48 yd³ x $45 = $66.67
Small Planter Box (3 x 1.5 ft, 8 in deep)
A patio planter that only needs a couple of bags.
- 1Convert depth: 8 in ÷ 12 = 0.667 ft
- 2Cubic feet = 3 x 1.5 x 0.667 = 3 ft³
- 3Bags (1.5 ft³) = 3 ÷ 1.5 = 2 bags
- 4Cubic yards = 3 ÷ 27 = 0.11 yd³
Introduction
The Soil Calculator tells you exactly how much soil you need to fill a garden bed, raised bed, or planter — in cubic yards, cubic feet, bags, and estimated cost. Just enter the area's length and width plus your target depth, and it converts everything for you. The core relationship is simple: volume = length × width × depth, with depth converted from inches to feet. Buying the right amount avoids the cost of a second delivery or a pile of leftover bags. For lawns, see our sod calculator; for blends, our potting soil calculator and compost calculator.
How the Soil Calculator Works
The calculator converts your bed dimensions into a soil volume and then into the units you actually buy: bulk cubic yards or bagged cubic feet.
Measure the bed length and width in feet, and the fill depth in inches
Convert depth to feet by dividing by 12
Cubic feet = length × width × (depth ÷ 12)
Cubic yards = cubic feet ÷ 27 (bulk soil is sold by the yard)
Bags = cubic feet ÷ bag size, rounded up to whole bags
Cost = cubic yards × your bulk price per yard
For round pots or beds, area = 3.14 × radius². Calculate the area first, then multiply by depth in feet for the volume.
Recommended Soil Depths
Different plants and projects need different soil depths. Use this guide to choose the right depth before calculating volume.
| Project | Recommended Depth | Notes |
|---|---|---|
| Lawn topdressing | 0.25-0.5 in | Thin layer to level and feed turf |
| Flower beds / annuals | 6-12 in | Most bedding plants and perennials |
| Vegetable garden | 12-18 in | Deeper for root crops like carrots |
| Raised beds | 8-12 in | Fill bed; mix with compost |
| New lawns (under sod/seed) | 4-6 in | Quality topsoil base |
| Tree / shrub planting | 18-24 in | Backfill amended native soil |
Cubic Yards, Cubic Feet, and Bags
Soil is sold two ways: in bulk by the cubic yard (delivered loose) or in bags measured in cubic feet. Knowing the conversions lets you compare prices fairly.
1 cubic yard = 27 cubic feet — the standard bulk unit
A cubic yard fills roughly 18 bags of 1.5 ft³ or 13.5 bags of 2 ft³
Bagged soil is convenient for small jobs but costs more per cubic foot
Bulk delivery is usually cheaper once you need about 1 cubic yard or more
One cubic yard of soil weighs roughly 1,800-2,200 lb depending on moisture
A standard pickup truck bed holds about 2-3 cubic yards of soil
Bag volumes vary by brand (0.75, 1, 1.5, and 2 ft³ are common). Check the bag label and enter the exact size for an accurate bag count.
Choosing the Right Soil
Not all 'soil' is the same. Picking the correct product for your project matters as much as getting the volume right.
- Topsoil:
general-purpose screened soil for filling and leveling
- Garden soil:
topsoil blended with compost/organic matter for in-ground beds
- Raised bed mix:
lighter blend of topsoil, compost, and aeration for containers and raised beds
- Potting mix:
soilless blend (peat/coir, perlite) for pots — not for filling large beds
- Compost:
rich organic amendment, usually mixed in at about one-third, not used alone
- Fill dirt:
cheap subsoil for raising grade — not for growing plants
Filling a Raised Bed Economically
Deep raised beds can need a lot of soil. A few strategies cut cost without harming plant health.
Aim for a blend of about 60% topsoil/garden soil, 30% compost, 10% aeration
For very deep beds, fill the bottom third with logs and branches (hugelkultur) to save soil
Coarse organic matter at the base improves drainage and breaks down over time
Keep the top 8-12 inches as quality growing mix where roots live
Buy bulk for anything over ~1 cubic yard to lower the per-foot cost
Expect soil to settle 1-2 inches the first season — top up with compost
Don't fill an entire 24-inch bed with premium potting mix — it's expensive and unnecessary. Reserve the rich mix for the root zone near the top.
Account for Settling and Compaction
Fresh soil and compost settle as they are watered and the organic matter breaks down. Planning for this prevents a sunken bed later.
Loose-delivered soil can settle 10-20% after watering and a few weeks
Order slightly more (about 10%) than the exact calculated volume
Water the bed and let it settle before final planting if time allows
Top up with compost each season as organic matter decomposes
Avoid compacting soil by walking on beds — use paths or boards
Compacted soil holds less water and air, harming root growth
Quick Reference Card
Soil Volume — Quick Reference
Quick reference • Soil Calculator
ft³ = L × W × (Depth÷12); yd³ = ft³ ÷ 27Valid range: Beds 6-18 in deep • 1 yd³ = 27 ft³
Common Values
⚠ Watch Out
- •Convert depth from inches to feet (÷ 12) before multiplying
- •Order ~10% extra for settling
- •Don't fill deep beds entirely with pricey potting mix
- •A full cubic yard can overload a small truck
Pro Tips
- →Buy bulk above ~1 cubic yard to cut cost
- →Mix in about one-third compost for beds
- →Use logs at the base of deep beds to save soil
- →Top up beds with compost each season
FAQs
How much soil do I need?
Multiply the bed length by its width (in feet) and by the depth in feet (inches ÷ 12) to get cubic feet, then divide by 27 for cubic yards. For example, a 9 x 6 ft bed filled 6 inches deep needs 9 x 6 x 0.5 = 27 cubic feet, which equals exactly 1 cubic yard, or about 18 bags of 1.5 ft³ soil.
How many cubic feet are in a cubic yard of soil?
There are 27 cubic feet in one cubic yard. This is because a cubic yard is 3 ft x 3 ft x 3 ft = 27 ft³. Bulk soil is sold by the cubic yard, so to convert a bagged-soil project to bulk, divide your total cubic feet by 27.
How many bags of soil are in a cubic yard?
It depends on the bag size. A cubic yard (27 ft³) equals about 18 bags of 1.5 ft³, 13.5 bags of 2 ft³, 27 bags of 1 ft³, or 36 bags of 0.75 ft³. Check your bag's labeled volume and divide 27 by that number to find how many bags equal a cubic yard.
How deep should soil be for a garden bed?
Most flower beds and annuals do well with 6-12 inches of good soil, while vegetable gardens benefit from 12-18 inches, especially for root crops. Raised beds are typically filled 8-12 inches deep. For trees and shrubs, prepare an 18-24 inch planting area. Choose your depth first, then calculate the volume.
Should I buy bagged or bulk soil?
Bagged soil is convenient and clean for small projects — a few bags for a planter or patch. Bulk soil delivered by the cubic yard is significantly cheaper per cubic foot and makes sense once you need about a cubic yard or more. The calculator shows both bag count and cubic yards so you can compare costs.
What is the difference between topsoil, garden soil, and potting mix?
Topsoil is general-purpose screened soil for filling and leveling. Garden soil is topsoil enriched with compost for in-ground beds. Potting mix is a lightweight, soilless blend (peat or coir plus perlite) designed for containers — it drains fast and shouldn't be used to fill large beds. Raised-bed mixes sit in between, blending topsoil, compost, and aeration.
How much does a cubic yard of soil weigh?
A cubic yard of soil typically weighs about 1,800-2,200 pounds (roughly a ton), depending on moisture and composition — wet soil is much heavier. A standard pickup truck bed holds about 2-3 cubic yards, but be mindful of your vehicle's weight rating, as a full load can exceed it.
Should I order extra soil for settling?
Yes. Freshly delivered loose soil and compost can settle 10-20% after watering and as organic matter breaks down. Ordering about 10% extra prevents a sunken bed. It's also good practice to top up beds with compost each season as the organic content naturally decomposes.
Can I fill a deep raised bed cheaply?
Yes. For deep beds, fill the bottom third with logs, branches, and coarse organic matter (a method called hugelkultur), which saves soil and improves drainage as it breaks down. Keep the top 8-12 inches as quality growing mix where roots are most active, and buy bulk soil rather than bags for the larger volumes.