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Calculator Answers

Topsoil Calculator

Blake Boege
Written by Blake Boege · Founder, Calculator Answers

A topsoil calculator is a gardening and landscaping tool that determines the amount of topsoil needed to fill a garden bed or cover a lawn. It takes the length and width of a rectangular area in feet, along with a depth entered in either inches or feet, and multiplies them to give the volume in cubic feet and cubic yards. It also estimates the equivalent weight and a bagged count from the volume. Gardeners, landscapers, and homeowners use this tool to budget material costs and coordinate delivery of soil bags or bulk trucks. The result is an order estimate rather than a measurement, because delivered soil settles and compacts.

Pick a project preset (or set a custom depth), enter the area, and the calculator returns cubic yards, an approximate weight, the number of bags, and a side-by-side cost comparison for bag and bulk delivery.

See also: Cubic Yard Calculator, Mulch Calculator, and Sand Calculator.

Quick Answer

Calculate the volume and weight of topsoil needed for lawns, gardens, and raised beds. Enter area dimensions and depth to get instant estimates.

Project preset

Mixed flower/vegetable bed: about 8 inches of topsoil.

Area and depth

ft
ft

Depth unit

Bag vs bulk

ft³

Common bagged topsoil is 0.75 ft³.

USD
USD

Density assumption

lb/ft³

Assumed, not measured. Defaults to 75; blank falls back to it.

Notes

  • Weight uses the density above. It is this tool's assumption rather than a measured figure, and the pounds and tons scale directly with it, so a supplier's own number is the better one to enter.
  • Bag count is volume based: it divides the cubic feet by the bag size, so the density does not change it. One cubic yard is 27 ft³, which is 36 bags at 0.75 ft³.
  • Cubic yards is what bulk soil is quoted in. Suppliers saying "yards" mean cubic yards, not length and not square yards.

This is an order estimate, not a measurement. Delivered soil settles and compacts, so the volume that arrives is not the volume that stays.

Topsoil order

Topsoil needed

0.99 yd³

26.67 ft³; about 1 ton

Volume26.67 ft³ (0.99 yd³)
Weight (approx)2,000 lb (1 ton)
Bags36

Bag count is rounded up to the next whole bag. Bag cost and bulk cost are shown when both prices are entered so you can pick the cheaper delivery option.

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Examples

10 x 4 ft garden bed, 8 in deep

26.67 ft³ · 0.99 yd³ · 36 bags

12 x 4 ft raised bed, 12 in deep

48 ft³ · 1.78 yd³ · 64 bags

20 x 20 ft lawn, 4 in deep

133.33 ft³ · 4.94 yd³ · 178 bags

10 x 4 ft bed, 0.25 in topdress

0.83 ft³ · 0.03 yd³ · 2 bags

How it works

Formula · cubic yards = (length ft x width ft x depth ft) / 27, with a depth given in inches divided by 12 first

Topsoil is a depth-driven calculation. Pick the right depth for your project and the calculator converts area and depth to cubic feet, cubic yards, and weight.

Volume · ft³ = L x W x D

Yardage · yd³ = ft³ / 27

Weight ≈ V (ft³) x 75 lb/ft³. Bag count is ceil(V / bag size).

Working it out by hand

Take one bed and follow it all the way through: 10 feet long, 4 feet wide, 8 inches deep. That is the calculator's own garden bed preset, so you can enter it above and watch every number below appear.

  1. 1. Put the depth in feet. Length and width are already in feet; the depth is not. Eight inches divided by 12 is 0.667 ft. This single step is where the arithmetic usually goes wrong.
  2. 2. Multiply for cubic feet. 10 x 4 x 0.667 = 26.67 ft³.
  3. 3. Divide by 27 for cubic yards. 26.67 / 27 = 0.99 yd³. Bulk soil is sold this way, so this is the number you order with. A bed this size is just under one yard.
  4. 4. Weight, if you want it. 26.67 x 75 = 2,000 lb, which is 1 ton. The 75 lb per cubic foot is the density field's starting value, an assumption rather than your soil, and the weight moves with whatever you put there.
  5. 5. Or count bags. At the common 0.75 cubic foot bag, 26.67 / 0.75 = 35.6, rounded up to 36 bags. You cannot buy part of a bag, so the count always rounds up.

Every preset works the same way. Lawn topdressing at 0.25 inches over the same bed is 0.83 cubic feet, a rounding error next to the 8 inch version. The 12 inch raised bed preset is 40 cubic feet, or 1.48 cubic yards. The depth is doing almost all of the work.

The one field with its own unit

Length and width are always in feet on this page. Depth is not, and that asymmetry is the whole trap.

length (ft)width (ft)depthdepth is the only field with its own unit

The diagram shows a rectangular garden bed drawn as a box with three labelled measurements. The length runs along the front edge of the bed and is measured in feet. The width runs back from the front edge and is also measured in feet. The depth is marked down the near side of the box and is highlighted, because it is the only measurement on this page that can be entered in either inches or feet. Length and width are always in feet.

length
Always feet
width
Always feet
depth
Inches or feet, your choice

Edge cases, and exactly what this tool does

Getting the depth unit wrong costs exactly 12x
Take the same 10 by 4 foot bed. Entered as 8 with the button on inches, it needs 26.67 ft³, which is 0.99 yd³. Entered as 8 with the button on feet, it needs 320 ft³, which is 11.85 yd³. Same typing, twelve times the soil, and a delivery you would be looking at for a long time. If a result seems roughly a dozen times off, check this button first.
Yards means cubic yards
Suppliers say three yards of topsoil and mean three cubic yards, a volume. It is not a length and it is not square yards of coverage. The calculator labels its output yd³ for that reason.
Bags round up, and only up
The bag count is the volume divided by the bag size, rounded up to the next whole bag. The worked bed above needs 35.6 bags of 0.75 cubic feet, so the calculator says 36. Bag cost follows the rounded count, because that is what you would actually pay, while bulk cost follows the unrounded cubic yards.
Rectangles only
The tool multiplies length by width, so it models a rectangle and nothing else. An L-shape can be split into rectangles and added up. A curved border, a circle or a genuinely irregular bed is outside what this estimate covers, and enclosing it in a rectangle will over-order rather than approximate it.
Empty or non-positive input
Length, width and depth must each be a positive number. Leave one blank, or enter 0 or a negative, and the result panel reads Cannot compute with the reason Length, width, and depth must be positive. rather than quietly treating the gap as zero and returning a total.

Bags or bulk, as arithmetic

The calculator will compare the two for you if you give it both prices, but the shape of the answer is easy to see. One cubic yard is 27 cubic feet, so at the common 0.75 cubic foot bag that is 27 / 0.75 = 36 bags to make a single yard.

Once a job is a few yards, that is a lot of bags to lift, open and dispose of, which is why bulk delivery tends to take over. Below about a yard the calculation often goes the other way, because a bulk load usually carries a delivery charge and needs somewhere to be tipped. Enter a price in both fields and the page shows the two totals next to each other rather than guessing which you meant.

An order is an estimate, not a measurement

The arithmetic on this page is exact: a box of those dimensions holds that many cubic feet, and you can check every step above by hand. What the arithmetic cannot tell you is how much soil your bed will take once it is real.

Loose soil carries air. It settles, it compacts under watering and foot traffic, and it moves with moisture, so the volume that arrives is not the volume that stays. Ground that looks flat has low spots that only show up once you start spreading. This page deliberately puts no percentage on any of that: the honest range depends on the soil, the site and the handling, and a figure invented here would read as far more precise than it is.

Use the number as what it is, a good starting quantity for an order. Your supplier delivers the same soil in the same conditions every week and can tell you what it usually does.

Your measurements stay in the page

The dimensions and prices you enter are processed by this page in your browser. They are not sent to a server, not stored after you close the tab, and not visible to anyone else. There is no account and nothing to sign up for.

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Frequently asked questions

Multiply length by width by depth, with all three in feet, to get cubic feet. Divide that by 27 for cubic yards, which is how bulk soil is sold. A depth given in inches has to be divided by 12 first. A 10 by 4 foot bed at 8 inches deep works out to 26.67 cubic feet, which is 0.99 cubic yards.

Divide by 27. A cubic yard is a cube three feet on every side, and 3 x 3 x 3 is 27, so one cubic yard holds 27 cubic feet. This trips people up because the numbers look small: a bed that takes 27 cubic feet of soil is only one cubic yard, which is a single small delivery rather than a truckload.

The buttons set the depth field for you: lawn topdressing uses 0.25 inches, garden bed uses 8 inches, and raised bed uses 12 inches. Custom leaves the depth to you. Those are the numbers this tool fills in rather than a recommendation about your soil. What depth a project actually needs depends on what you are planting and what is already underneath, which is a question for local guidance rather than arithmetic.

Proportionally, and it is the input people underestimate. On a 10 by 4 foot bed, every extra inch of depth adds 3.33 cubic feet, so going from 6 inches to 12 inches doubles the order. Because depth is the only one of the three numbers usually given in inches, it is also where the largest mistakes come from.

Length and width on this page are always in feet. Depth is the one field with its own unit button, and it defaults to inches. If you type 8 meaning inches but leave the button on feet, the calculator faithfully computes a bed eight feet deep. On a 10 by 4 foot bed that turns 26.67 cubic feet into 320 cubic feet, an order twelve times too large. The error is always exactly 12x in one direction or the other, so a result that looks roughly a dozen times off is nearly always this.

Bulk soil is ordered by the cubic yard but often arrives with a weight on the delivery ticket, so a rough weight lets you sanity-check what turned up. The tool converts volume to weight using the density field, which starts at 75 pounds per cubic foot. That default is the tool's assumption rather than a measurement of your soil: real bulk density moves with moisture, texture and organic content, so treat the weight as the softest number on the page.

Yes. The density field takes pounds per cubic foot and starts at 75, which is an assumed figure rather than a measured one, so if your supplier quotes a density, enter theirs. The weight and tonnage scale directly with it: double the density and the weight doubles. The volume and the bag count do not move, because cubic feet and cubic yards are geometry and bagged soil is sold by volume. Leave the field blank or enter something unreadable and it falls back to 75 rather than weighing the load at nothing.

It is an arithmetic question before it is a preference. Bagged soil is sold in small volumes, commonly 0.75 cubic feet, so one cubic yard of soil is 36 bags at that size. Enter a price per bag and a price per cubic yard and the calculator shows both totals side by side, which is usually enough to settle it. Bags win on very small fills and on not needing somewhere to tip a pile.

With the common 0.75 cubic foot bag it is 36, because 27 divided by 0.75 is 36. Bag sizes differ between suppliers, so the calculator asks for the bag size rather than assuming one. It also rounds the bag count up to the next whole bag, since you cannot buy part of one.

Yes. Loose soil is full of air, and it loses volume as it settles, gets watered, and is walked on. That is why an order is an estimate and not a measurement. How much it drops depends on the soil and how it is handled, which is why this page does not quote a settling percentage: any single number would be invented rather than measured.

Many people do, for settling and for the low spots that only appear once you start spreading. This page will not tell you what fraction to add, because that depends on your soil, your site and your supplier, and a number made up here would look more authoritative than it deserves. Your supplier sees the same soil delivered every week and is the better source.

This calculator multiplies length by width, so it estimates rectangles. For an L-shape, split it into rectangles, run each one, and add the cubic feet. For a circle, a triangle or a genuinely irregular border, the rectangle that encloses it will over-order, and the honest answer is that a shape this tool does not model is beyond what it can estimate.

A slope means the depth is not one number, so a single depth entry cannot describe it. Measuring the depth at several points and using the average gets you a workable estimate, and it is worth knowing that it is an average rather than a measurement. Substantial regrading is earthwork and is a different job from ordering soil.

Cubic yards. When a soil or mulch supplier quotes yards they are talking about volume, not length. It is worth confirming on the order, because a yard of soil and a square yard of coverage are very different quantities and the word alone does not distinguish them.

The volume arithmetic is identical, so the cubic feet and cubic yards would be right. The weight would not be, because this page assumes soil. Each of those materials has its own page here with its own densities and bag sizes, which is the better route.

Yes. It is free to use with no account, no sign-up, and no limit on calculations. Everything runs inside this page in your browser.