Soil Calculator – Estimate Topsoil

Calculate the soil, topsoil, or fill dirt needed by entering the length, width, and depth of the space you want to fill. Read below for more details.

Find area using our square footage calculator

How Much Soil You Need:

Cubic yards
Cubic feet
Number of Soil Bags
0.75 cu. ft. bags
Material Weight (dry, loose or packed)
Material Weight (wet)
Learn how we calculated this below

scroll down

On this page:

How Much Topsoil Do You Need?

When you are creating or refreshing a garden or other landscape feature, often you want to add new topsoil to the area. And, in the case of new raised beds, you might need enough new soil to fill your new box completely.

New soil gives your plants the nutrients, air circulation, and water drainage that they require to thrive.

Estimating the amount of soil needed for a garden

To achieve that balance, it’s a good idea to mix soil, compost, and potting blends for the best plant growth. Generally, a good proportion is 60% topsoil, 30% compost, and 10% potting mix if you are growing flowers, 20% compost and 70% topsoil if planting vegetables, or 10% compost if planting trees.

You may also need fill-dirt for landscaping projects and hardscapes, which is used to fill in large volumes. This may be leveling off an area or securing the area around a retaining wall.

Steps to Measure for Soil

Adding soil can be a substantial investment in time and money. To minimize work and expense, follow these instructions for getting the right amount of soil that you need.

1.   Using a tape measure, measure the length and width of the area(s) you want to fill. It’s best to write these numbers down.

2.   If the space is complex, break the area into smaller, regularly shaped sections, like in the diagram below. Then measure each section separately.

diagram showing how to measure a complex area
Diagram 1. Break your garden into sections to measure.

3.   Decide on the depth of the new soil that you want. For refreshing gardens, usually, 3-6 inches (76-152 mm) of new soil is sufficient. If you have a hard border or a raised bed, measure the depth of the partition. Remember that soil will settle, so be a little generous with this measurement.

4.   By far, the easiest way to calculate quantities is to use the soil calculator above! Enter your measurements, hit calculate, and it’s all worked out for you: cubic feet, yards, even the number of bags. And metric too.

Sometimes topsoil and compost are sold by weight, which varies depending on what the material is. In the US, a 40-pound bag measures between 0.5 and 0.75 cubic feet. The soil calculator bag estimation is based on 0.75 cubic feet per bag.

Steps to Calculate Soil Volume

If you want to do the calculations by hand, then skip Step 4 above, and do the following:

1.   Make sure all measurements are in the same units (usually inches or centimeters). The following calculation will use inches as an example to translate into cubic feet.

2.   Multiply your length, width, and depth in inches together to find your total cubic inches (length × width × depth). Divide this by 1,728 to find the volume in cubic feet.

3.   If you’re measuring multiple sections, add the volumes for each together.

4.   The result is the minimum volume of soil required for your project. You will need to figure the number of bags depending on what size you buy.

illustration showing the cubic yards formula

No matter how you get your total, you should consider buying in bulk by the cubic yard (or cubic meter) if you need a lot of material. The calculator above provides this volume for you.

For hand calculators, divide your total cubic feet by 27 (3×3×3) to get cubic yards.

Be sure to check your calculations and confirm your measurements using a cubic yards calculator. Give this number to your supplier, who will usually deliver the soil to your location for a small fee.

Soon your plants will be enjoying their new environment, and you will be enjoying your happy plants!

Check out our mulch calculator to estimate mulch for your garden bed, or see our gravel calculator to estimate stone, gravel, and other landscaping materials.

How Much is a Yard of Dirt?

At this point, you still might be wondering just how much is a yard of dirt?

One cubic yard is equal to a space that is one yard wide, one yard long, and one yard deep. The table below shows the size of the space equal to one cubic yard of soil in other units of measurement.

Measurements in various units of a space with the volume of one cubic yard of soil.
1 cu yd = 1 yd x 1 yd x 1 yd
1 cu yd = 3 ft x 3 ft x 3 ft
1 cu yd = 36 in x 36 in x 36 in
1 cu yd = 0.9144 m x 0.9144 m x 0.9144 m
1 cu yd = 91.44 cm x 91.44 cm x 91.44 cm

How to Estimate Soil in Tons

You can calculate how much soil you need in tons by multiplying its density, which is the weight of one yard of soil by the volume, which is the number of yards you need.

How Much Does a Yard of Topsoil Weigh?

So, how much does a cubic yard of dirt weigh? One yard of dry or loose soil weighs 1.0 – 1.3 tons, while one yard of wet or compacted soil weighs 1.5 – 1.7 tons.

Calculate the Total Weight

Once you know the density and total volume, use the following formula to calculate how much soil you need in tons.

weight (tons) = volume (yds) × density (tons/yd)

Thus, the amount of soil needed in tons is equal to the volume in yards times the density.

You might also be interested in our stone and sand calculators for more landscaping material estimates.

How to Calculate Soil Amendment

If you have had your soil tested and you need to amend the pH to better accommodate the types of plants you are growing, you will need to determine the correct amount of amendment to add to the soil.

Soil pH is the measurement of acidity or alkalinity in the soil on a scale of 1 – 14, with 7 being neutral. Because different plants require different pH measurements, you may need to amend your soil for the best growth.

Calculating Soil Amendment by Weight

Some soil amendments are calculated by weight, or the number of pounds of amendment needed for 100 square feet. To calculate this, multiply the length and width of the space in feet to find the square footage.

Next, you’ll need to get the amendment’s application rate, which can be found on the packaging. This is usually given in pounds per 100 square feet.

For example, for a 350 square-foot garden and an amendment rate of 2 pounds per 100 square feet, you would need 7 pounds of amendment using this calculation:

2 lbs ÷ 100 sq ft × 350 sq ft = 7 lbs

Calculating Soil Amendment by Volume

If the amendment is being added in large volumes, such as compost, that you may be purchasing by the yard, you will use a different calculation. For this, you need to know the number of total inches you want to apply converted into feet.

Next, multiply this by the number of square feet in your garden, then divide by 27 to get the total number of cubic yards of amendment required.

For example, for a 350 square-foot garden and a 3″ amendment, you would need 3.24 cubic yards of amendment using this calculation:

350 × 3/12′ = 87.5 cu ft
87.5 cu ft ÷ 27 = 3.24 cu yds

You can round up to ensure you have enough material for the garden, even if settlement occurs.

Frequently Asked Questions

Do you buy soil by the yard or ton?

This actually depends on the seller. Some will specify by the cubic yard, while others will specify by the ton; you can use the number of cubic yards you need to determine the number of tons if needed.

Is there a difference between soil and topsoil?

Topsoil is defined in the landscaping industry as soil that has been screened. The screening removes debris, pebbles, and large clumps to create an even texture.

Are soil and dirt the same thing?

While the terms may be used interchangeably at times, these are different things. Dirt is organic matter that includes sand, clay, pebbles, and rocks, but no nutrients or microorganisms that can help plants grow, while soil contains decomposed bedrock along with ecosystems made up of microorganisms and insects.

Do you need to amend your soil?

Not necessarily. Amendment can help correct the pH of your soil if it’s not right for the type of plants that you want to grow; you need to have your soil tested to find out its current pH before you know whether or not to amend it.

What is soil made of?

Soil is made up of a blend of decomposed materials and elements, including bedrock, along with living microorganisms, insects, and nutrients. Different types of soil may have different chemical make-ups, but each one is considered a living ecosystem that can help plants grow.