Mulch Calculator

1. Mulch calculation process
• Square or rectangular area to fill with mulch
• Round garden area
• Irregularly shaped space
2. Mulch basics
3. Wood vs Rubber mulch - a comparison
4. Purchasing mulch in bulk versus in bags

    Mulch calculation process

Many gardeners and playground builders are faced with calculating or estimating the amount of mulch they need to cover a given garden area or playground area with it. If you're asking yourself "How much mulch do I need?", our mulch calculator would be of great utility in getting an answer. You can use it to assist you in this task, but keep in mind that the results will only be as good as the measurements entered.

The calculation process is the same for wood mulch and rubber mulch, and is as follows:

1. Estimate the volume of mulch needed, using geometrical formulas and plans or measurements.
2. If bag size and price are specified, divide by the bag volume, to calculate the number of bags.
3. If bulk order price is specified (per cu yd or per cu meter), multiply the resulting volume by the price to get a total price.

In the process of step #2 the price per cubic yard or cubic meter is calculated as well, allowing you to easily compare mulch prices from retail and bulk vendors using this tool. It is a good advice to consider purchasing slightly more mulch than what is estimated via our rubber mulch calculator, especially if uneven ground makes it harder to estimate the average depth of the area. 2 inches is the generally recommended minimum depth.

Square or rectangular area to fill with mulch

If a gardening project requires a rectangular shape to be filled with mulch the simple volume formula for a rectangular (or square) box in cubic feet is height(ft) x width(ft) x length(ft) is as shown in the figure below:

For example, to fill with mulch a rectangular playground with a width of 10ft and a length of 22ft, to a depth of 1in, you need to multiply 0.083ft x 10ft x 22ft = 18.333ft³ (cubic feet) of mulch. To convert the amount of rubber mulch required from cubic feet to cubic yards, divide by 3^3 = 27 to get 0.679yd³ (a cubic foot is 1/27 of a cubic yard, or about 0.037 cubic yards). So you would need 0.679 cubic yards of mulch.

Round garden area

If the garden area you want to cover, or the shape you want to fill with mulch is round, the calculation for how much mulch is needed is a bit different:

The volume of a figure with a round shape is its depth times the surface area which is exactly the formula for the volume of a cylinder. To calculate the surface area we need its diameter, since the mulch calculation formula is π x r², where r is the radius, or diameter/2. For example, if the volume you want to fill is two inches deep and four feet in diameter, the area is 50.265ft² or approximately 50 square feet hence the amount of mulch needed would be 50 x 2/12 = 50 x 0.166(6) = 2.094 cubic feet or approximately two cubic feet (0.078 cubic yards).

Irregularly shaped space

In some cases the landscaping project is more complex and the outdoor area you are calculating has an irregular shape. What you want to do then is to divide it in several regularly-shaped sections, calculate their volume and mulch requirements using our online tool and then sum them up together. If you need to do this for a large number of sections, you might use our summation calculator next.

    Mulch basics

A layer of material applied to the surface of soil is called mulch. It comes in two main types, organic mulch and synthetic mulch. Most commercial organic mulches (straw apart) are wood byproducts from the lumber industry, while synthetic ones are usually shredded old tires from cars, trucks, and other vehicles. Some organic mulch can actually be found just laying around, e.g. fallen leaves and grass clippings are excellent for flower and perennial beds, especially if shredded.

Applying mulch is usually done only after a careful mulch calculation so that you don't end up under or overestimating the needed amount. Adding mulch aims to conserve the soil moisture, to improve soil fertility & health, to hinder weed growth and last, but not least, to enhance the visual appeal of the garden or yard. A layer of mulch over the topsoil works great for most plants as it insulates them - keeping their temperature more steady and protecting roots from both cold and hot. It also keeps soil moisture from evaporating quickly, so can water less often. In addition, it has a weed-prevention function, as it shades out weed seeds, stagnating their growth due to insufficient sunlight.

Mulch for domestic or garden use is usually sold in packets of several cubic feet (1, 1.5, 2 and 3 cu ft are standard) in the USA. Homeowners in Europe can expect to see bags measuring 10-s of liters (e.g. 20l, 40l, 60l bags). For larger projects it is sold by the cubic yard or cubic meter, and more rarely by ton or tonne, or truckloads.

    Wood vs Rubber mulch - a comparison

The type of mulch filling you use can have a significant impact on your garden and on your long-term budgeting and finances. Both tree wood and rubber mulch have advantages and disadvantages and where one works better in some places, the other excels at others. Selecting the right type for your garden or playground is crucial.

Mulch types comparison

Type	Pros	Cons
Wood Mulch	Provides additional nourishment over time, as with time wood releases nutrients into the soil, enhancing its fertility. Great natural color. Easier to weed and add new plants. Can be used in any garden.	Poor longevity, needs to be replenished by end of season. Heavy rain may displace it. Color may be washed out with time. Some animals & insects are attracted to the wood chips (termites, carpenter ants...).
Rubber Mulch	Does not decompose, does not require replenishing. Stays in place, even heavy rainfall won't displace it. Lasting color that does not wash out. Discourages animals and insects from entering the garden.	No additional nourishment for the soil. May leak heavy metals like zinc. Fire hazard.

As you can see from the table, rubber mulch vs wood mulch is not an easy choice! When calculating dollar and time costs, make sure to consider not only the one-time investment, but maintenance over a period of 5 or 10 years, in order to get a fairer comparison, otherwise the bark chips may get an unfair advantage. Our calculator can only partially help, but not completely solve this riddle for you, as it is all about the seeds you intend to plant and the overall look you aim to achieve for the outdoor project.

In some garden projects compost is considered as an alternative to mulch, but we will not discuss this option here.

    Purchasing mulch in bulk versus in bags

As with any good, there are advantages and disadvantages in purchasing mulch in bulk versus purchasing in smaller bags or sacks. Our mulch calculator will not only tell you how much mulch you need, but will also compute the cost based on either a price per bag or per cubic yard / cubic meter, allowing you to compare your mulch purchasing options.

The plus of the smaller packaging is convenience: they are more widely available, you don't need a special vehicle to transport them, it is usually easier to store mulch in bags as well. The minus of buying in bags from a retail store is that the cost per cubic yard is higher. That's due to the packaging expenses, cost of shell space, and other factors.

The pros of bulk ordering mulch are that you may save significant percentages versus the price you usually pay when buying by the bag. Depending on the size of your order, you might be able to get an additional discount as well. However, the minuses are higher transportation costs, harder handling, and the need for storage, if you can't use all the mulch at once. Whether you purchase by the tonne, by the kilo / pound, or by the bag, our free calculator is here to aid you.

Is one way preferrable to the other? As always, the answer is: it depends on your particular circumstances and needs, so choose your mulch packing options wisely.

Note: If you are looking for a mulch calculator widget for your website, just follow the "Embed this tool" link next to it.