Understanding your result
The headline is the total volume to buy, extra included. The line below gives the same amount as whole bags and as a bulk order rounded up to the step suppliers actually sell.
What the depth figure means depends on the job you chose:
- Spreading a layer: the depth is simply how thick the new layer will be.
- Digging compost in: the calculator works out how thick a layer of compost to spread before you dig, so that it ends up as your chosen share of the mixed soil. That layer depth is shown in the table.
- Top-dressing a lawn: the depth is the thin coat you rake into the turf. The table adds a spreading rate, so you can check your progress as you work across the lawn.
The weight range is wide on purpose. Soil delivered after rain weighs far more than the same soil in a dry spell. Use the top of the range when you decide how to transport it.
How we calculate this
All three modes end in the same sum. Only the depth is worked out differently.
For digging compost in, the depth of the compost layer comes from the share you want in the finished soil:
So a 25% share in soil dug 8 inches deep means a 2 inch layer of compost. Strictly speaking the mixed soil ends up slightly deeper than 8 inches, because you have added material. For garden purposes the difference is too small to matter.
For lawns, the spreading rate is the volume before the extra allowance, scaled to 1,000 square feet (or to 100 square meters in metric).
The assumptions behind the numbers
| Assumption | Value used | Why |
|---|---|---|
| Extra allowance | 5% unless you change it | Ground is never perfectly level, and some material is lost in spreading |
| Bag sizes | 0.75, 1, 1.5 and 2 cu ft; 25, 40, 50 and 70 L | Topsoil is often sold in 0.75 or 1 cu ft bags, compost in 1 to 2 cu ft |
| Bulk rounding | Up to the next 0.5 cu yd or 0.25 m³ | The smallest step most suppliers will load |
| Topsoil weight | 2,000 to 2,700 lb per cu yd | Dry and loose at the low end, wet at the high end |
| Compost weight | 1,000 to 1,600 lb per cu yd | Compost is lighter and more variable than soil |
| Blend weight | 1,400 to 2,200 lb per cu yd | Between the two, depending on the recipe |
| Lawn top-dressing | Warning above 1/2 in (1.3 cm) | Thicker layers can smother the grass |
Assumptions last reviewed October 3, 2026.
The calculator does not allow for compaction of topsoil used as fill. If you are raising the level of an area and will firm the soil down, add 10 to 15% in the extra allowance box, because loose soil loses height when it is trodden or rolled.
Two worked examples
Top-dressing a lawn with compost
A back lawn measures 50 feet by 30 feet. It is getting a quarter-inch top-dressing of screened compost after aeration.
- Area: 50 × 30 = 1,500 sq ft
- Volume: 1,500 × 0.25 ÷ 12 = 31.3 cu ft
- With 5% extra: 32.8 cu ft, which is 1.22 cu yd
- Spreading rate: 0.77 cu yd per 1,000 sq ft
- In 1 cu ft bags: 33 bags
- In bulk: 1.5 cu yd
The spreading rate is the useful number on the day. This lawn is one and a half “thousands”, so when half the pile is gone, about half the lawn should be covered. If you are ahead or behind, adjust how thickly you are throwing it.
Preparing a new vegetable bed
A new bed is marked out at 12 feet by 6 feet. The soil will be dug to 8 inches, and the aim is for compost to make up a quarter of the dug layer.
- Area: 12 × 6 = 72 sq ft
- Compost layer: 8 × 25 ÷ 100 = 2 in
- Volume: 72 × 2 ÷ 12 = 12 cu ft
- With 5% extra: 12.6 cu ft, which is 0.47 cu yd
- In 1 cu ft bags: 13 bags
- In bulk: 0.5 cu yd
Half a yard is under most suppliers’ delivery minimum, so this is a job for bags, or for a trip with a trailer if you have one. Thirteen one-cubic-foot bags of compost weigh somewhere between 500 and 750 pounds in total, which most cars can manage in two loads.
Common mistakes
- Ordering topsoil when you need a blend. Plain topsoil is fine for filling and leveling. For beds that will grow vegetables or flowers, you want compost in it as well.
- Burying a lawn. Top-dressing is a dusting, not a blanket. If you cannot see the grass afterward, it is too thick.
- Forgetting that loose soil sinks. A 4 inch layer of loose topsoil becomes about 3.5 inches once it has been walked on and rained on. Allow for it when raising a level.
- Measuring depth in inches and area in feet, then multiplying them directly. Divide the inches by 12 first, or use the calculator.
- Assuming all bags are the same size. Topsoil is commonly sold in 0.75 cubic foot bags labeled by weight (“40 lb”). Check the volume on the label before you count bags.
- Collecting bulk soil in a vehicle that cannot carry it. A cubic yard of damp topsoil can weigh well over a ton. Check your payload first.
Printable shopping list
Press Print shopping list under the calculator for a one-page summary: bags or bulk quantity, the breakdown, and your measurements. For a lawn, write the spreading rate at the top of the page and keep it in your pocket while you work.
When you phone a supplier, ask three things: what the product is screened to (half an inch or finer is easier to spread), whether it is sold by the yard or by the ton, and what the delivery minimum is. If they sell by weight, the weight range in the table gives you a rough conversion.
Questions people ask
- How much topsoil do I need for 1,000 square feet?
- It depends on the depth. At 1 inch deep, 1,000 square feet takes 83 cubic feet, which is about 3.1 cubic yards. At 4 inches it takes 12.3 cubic yards. Multiply the depth in inches by 3.1 to get cubic yards per 1,000 square feet.
- How much compost should I add to a new garden bed?
- A common target is for compost to make up 20 to 30% of the soil you dig. If you are digging 8 inches deep, that means spreading about 2 inches of compost and mixing it in. The calculator does this sum in its "Digging compost in" mode.
- How thick should lawn top-dressing be?
- About a quarter of an inch (roughly 0.6 cm), and no more than half an inch in one application. The grass blades should still be clearly visible after you rake it in. That quarter inch works out to about 0.77 cubic yards per 1,000 square feet.
- How many bags of topsoil make a cubic yard?
- A cubic yard is 27 cubic feet, so it takes 27 bags of 1 cubic foot, 36 bags of 0.75 cubic feet, or 18 bags of 1.5 cubic feet. That is why anything over about a yard is usually cheaper and easier in bulk.
- Is topsoil the same as garden soil?
- Not quite. Topsoil is screened mineral soil with whatever organic matter it came with. Products sold as garden soil are usually topsoil blended with compost. For filling and leveling, plain topsoil is fine. For planting beds, a blend or topsoil plus compost grows better plants.
- How heavy is a cubic yard of topsoil?
- Roughly 2,000 to 2,700 pounds, depending on how wet it is. Compost is lighter, around 1,000 to 1,600 pounds. A half-ton pickup can usually carry about half a yard of topsoil safely, so check your payload before you collect it yourself.
Built and reviewed by Bertha
Last updated · How we work out our numbers