Mulch & Topsoil Calculator: Cubic Yards & Bag Count by Depth
Buying mulch or topsoil by guesswork almost always leads to a second trip to the store, since coverage depends on both bed area and how deep you spread it. This calculator handles rectangular, circular and triangular beds and converts your target depth directly into cubic yards, delivery tonnage and bag counts.
You need 1.85 cu yd (25 bags of 2 cu ft) to cover 200 sq ft at 3 in deep.
| Metric | Value |
|---|---|
| Bed shape | rectangle |
| Area | 200 sq ft |
| Depth | 3 in |
| Volume | 50.0 cu ft (1.85 cu yd) |
| Bulk delivery est. | ~0.93 tons |
| 2 cu ft bags | 25 |
- 1.
Area (rect) = Length × Width; (circle) = π×(D/2)²; (triangle) = 0.5×Base×Height - 2.
Volume_CuFt = Area × (Depth/12) - 3.
CubicYards = Volume_CuFt / 27 - 4.
Bags = ceil(Volume_CuFt / BagSize)
How to Use This Calculator
1. Enter your details
Use the labelled fields and units that match your situation.
2. Calculate instantly
The result, visual comparison, and working update as values change.
3. Review your result
Check assumptions, then copy, print, or share the calculation.
Formula & step-by-step maths
- Depth
- Target mulch/soil depth (in)
- BagSize
- 2 or 3 cu ft bag
Why depth matters more than most people expect
Doubling your mulch depth from 2 to 4 inches doubles the volume needed for the same bed — a detail many first-time buyers overlook when eyeballing quantity. Most landscapers recommend 2-3 inches for mulch, since going deeper can suffocate roots and encourage fungal growth against tree trunks.
Bulk delivery vs bagged: the cost crossover point
Bulk mulch delivered by the cubic yard is almost always cheaper than bagged mulch once you need more than about 2-3 cubic yards (roughly 15-20 bags), since bagged products carry a packaging and retail markup. For small beds under 1 cubic yard, bags are usually more convenient and cost-competitive.
Calculating irregular and circular beds
Circular beds use the standard circle area formula (π × radius²), while triangular beds use half of base times height — entering your bed's longest dimensions accurately here matters more than for rectangles, since small measurement errors compound faster in curved shapes.
Topsoil vs mulch density differences
Topsoil is considerably denser than shredded bark mulch, so bulk delivery weight estimates differ meaningfully between the two materials even at identical volumes. Always confirm density with your specific supplier, since compost-blended and screened topsoil products vary in bulk density by 20% or more.
Reference: cubic yards needed by area (at 3 in depth)
| Area | Cubic yards |
|---|---|
| 100 sq ft | 0.93 cu yd |
| 250 sq ft | 2.31 cu yd |
| 500 sq ft | 4.63 cu yd |
| 1000 sq ft | 9.26 cu yd |
| 1500 sq ft | 13.89 cu yd |
| 2000 sq ft | 18.52 cu yd |
Frequently Asked Questions
Three worked examples
Same engine, three different starting points — useful if you want to see how sensitive the answer is before you type your own numbers in.
Example 1: length (or diameter for circle) 15.6 ft, bed shape "Rectangle"
On the lower / more conservative end. You need 1.44 cu yd (20 bags of 2 cu ft) to cover 156 sq ft at 3 in deep.
Example 2: length (or diameter for circle) 20 ft, bed shape "Rectangle"
A typical middle-of-the-road setup. You need 1.85 cu yd (25 bags of 2 cu ft) to cover 200 sq ft at 3 in deep.
Example 3: length (or diameter for circle) 26 ft, bed shape "Circle"
On the higher / more demanding end. You need 4.92 cu yd (67 bags of 2 cu ft) to cover 531 sq ft at 3 in deep.
Quick answers about the Mulch & Topsoil Yardage
What exactly does the Mulch & Topsoil Yardage work out?
Buying mulch or topsoil by guesswork almost always leads to a second trip to the store, since coverage depends on both bed area and how deep you spread it. You enter bed shape, length (or diameter for circle), width (ignored for circle) and target depth (plus 1 more optional details) and the result panel updates straight away, so you can compare two or three versions of the same question in a few seconds.
What do I need before I start?
Only 5 fields: bed shape, length (or diameter for circle), width (ignored for circle), target depth and bag size. Nothing else is needed and nothing is stored.
How is it calculated — why depth matters more than most people expect?
Doubling your mulch depth from 2 to 4 inches doubles the volume needed for the same bed — a detail many first-time buyers overlook when eyeballing quantity. The same maths runs inside this page, so hand-checking the result on paper gives you the identical figure.
Why do two calculators give me different answers for mulch & Topsoil Yardage?
Bulk mulch delivered by the cubic yard is almost always cheaper than bagged mulch once you need more than about 2-3 cubic yards (roughly 15-20 bags), since bagged products carry a packaging and retail markup. Different sites pick different assumptions, so always check which method a calculator states before you trust the gap between two numbers.
What does the "Reference: cubic yards needed by area (at 3 in depth)" table on this page tell me?
It is the reference range this tool works against — 6 rows from "100 sq ft" (0.93 cu yd) up to "2000 sq ft" (18.52 cu yd). Use it to sanity-check whether the number you just calculated sits where you expected it to.
Which bed shape should I pick?
The dropdown offers 3 choices — Rectangle, Circle and Triangle. Pick the one that matches your real situation rather than the one you would like to be true; bed shape usually moves the final figure more than any other single input, so it is worth running it twice with the option above and below your guess.
Do I have to press a button or reload the page to see the result?
No. Mulch & Topsoil Yardage runs completely inside your browser, so the moment you change a value the cards recalculate — there is no submit step, no page reload and no waiting for a server round trip. That also means it keeps working on a weak or intermittent mobile connection.
Is it free, and do you keep what I type?
It is free with no sign-up, no app install and no usage limit. Nothing you enter into Mulch & Topsoil Yardage leaves your device — the calculation is JavaScript running locally, so there is no upload of your figures to DrHint or anyone else.
Can I use it on a phone?
Yes — the layout stacks to a single column on small screens and the number fields open the numeric keypad on both Android and iOS. Many people bookmark this page or add it to their home screen and re-open it whenever the question comes up.
Anything to be careful about with the result?
500 sq ft at 3 inches deep requires about 4. Treat the output as a well-grounded estimate for planning, not as a professional, legal or medical decision on its own.
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