Mulch and Gravel Calculator
Calculate material needed for landscaping projects
How to Use This Calculator
Accurately measuring your landscaping beds ensures you purchase the right amount of mulch without waste or shortage. Start by sketching your yard and identifying all areas that need mulch coverage.
Measuring bed areas: For rectangular beds, simply measure the length and width in feet. For irregular shapes like curved flower beds, break the area into smaller rectangles or use the average width method. Measure the longest dimension as length, then take width measurements at three points and average them. For circular beds around trees, measure the diameter and use our circular area option, or calculate separately using the formula: radius squared times 3.14.
Selecting the right depth: Mulch depth varies based on your goals and existing conditions. For new beds with no existing mulch, 3 to 4 inches provides optimal weed suppression and moisture retention. For refreshing existing mulch, 1 to 2 inches on top is usually sufficient. Vegetable gardens typically need only 2 inches, while perennial borders benefit from 3 inches. Always measure existing mulch depth before calculating how much to add.
Pro tip: Walk your property with a measuring tape and notepad. Record each bed separately, then add them together for your total order. This method also helps you track how much mulch goes where during installation.
Understanding Mulch Coverage
Choosing the right mulch type affects both aesthetics and long-term maintenance costs. Understanding the differences between materials helps you make an informed decision for your landscape.
Wood Mulch Varieties
Hardwood mulch, made from oak, maple, and other deciduous trees, breaks down over 2 to 3 years, adding valuable organic matter to soil. It holds its color reasonably well and creates a classic, natural appearance. Cedar and cypress mulches contain natural oils that resist decay and repel certain insects, making them ideal for areas near outdoor living spaces. Pine bark mulch comes in nuggets or shredded form, with nuggets lasting longer but potentially floating away in heavy rain. Dyed mulches in black, red, or brown maintain vibrant color for one to two seasons but may contain recycled wood pallets treated with chemicals.
Rubber Mulch
Made from recycled tires, rubber mulch lasts 10 years or more without decomposing. It provides excellent cushioning for playground areas and does not attract termites or other pests. However, rubber mulch does not improve soil health, can get extremely hot in direct sunlight, and may release zinc and other compounds into soil over time. It costs more upfront but requires no annual replacement.
Stone and Gravel Options
Decorative stone, river rock, and pea gravel provide permanent ground cover that never needs replacement. These materials work best in dry climate gardens, around foundations, and in drainage areas. Stone mulch reflects heat and does not retain moisture like organic options, making it less suitable for most plantings but excellent for xeriscaping and Mediterranean-style gardens.
Understanding Cubic Yards
A cubic yard is a volume measurement equal to 27 cubic feet, roughly the size of a standard washing machine. One cubic yard of mulch covers approximately 100 square feet at 3 inches deep, or 160 square feet at 2 inches deep. Bulk mulch is sold by the cubic yard, while bagged mulch typically comes in 2 cubic foot bags, meaning you need about 13.5 bags to equal one cubic yard.
Bags vs. Bulk: Cost Comparison
Bagged mulch costs $3 to $6 per 2 cubic foot bag, translating to $40 to $80 per cubic yard. Bulk mulch runs $20 to $45 per cubic yard, with delivery fees of $50 to $100 depending on distance. For projects requiring less than 2 cubic yards, bags may be more economical when factoring in delivery costs. For larger projects, bulk delivery saves 30 to 50 percent on material costs.
Organic vs. Inorganic Mulch
Organic mulches decompose over time, feeding soil microorganisms and improving soil structure. They require annual refreshment but create healthier growing conditions for most plants. Inorganic mulches like rubber and stone last indefinitely but provide no soil benefits and can actually inhibit plant growth by reflecting excessive heat or preventing natural soil processes.
Frequently Asked Questions
How deep should mulch be?
The ideal mulch depth depends on your specific situation. For most garden beds and landscaped areas, 2 to 4 inches works best, with 3 inches being the sweet spot for weed suppression and moisture retention. Around trees, maintain 2 to 3 inches but keep mulch at least 6 inches away from the trunk. For vegetable gardens, 2 inches is sufficient since you will be disturbing the soil regularly. Never exceed 4 inches total depth, as excessive mulch suffocates roots, promotes fungal growth, and can cause plants to develop shallow root systems that make them susceptible to drought stress.
Is bagged or bulk mulch more cost-effective?
Bulk mulch typically costs 30 to 50 percent less per cubic yard than bagged mulch when you factor in material costs alone. A cubic yard of bulk hardwood mulch runs $25 to $40, while the equivalent in 2 cubic foot bags costs $50 to $80. However, bulk delivery adds $50 to $100 in fees. The break-even point is usually around 2 to 3 cubic yards. For smaller projects, bagged mulch eliminates delivery fees and provides easier handling. For larger projects exceeding 3 cubic yards, bulk delivery offers significant savings and reduces plastic waste from bags.
How often should mulch be replaced?
Organic mulch does not need complete replacement each year. Instead, refresh existing mulch by adding 1 to 2 inches on top annually, typically in spring before summer heat arrives. Complete removal and replacement is only necessary every 3 to 4 years when the bottom layer has fully decomposed into soil, or if you notice fungal issues or pest problems. Inorganic mulches like rubber or stone last 10 to 20 years but should be cleaned annually to remove debris, fallen leaves, and weed growth.
How should I mulch around trees?
Proper tree mulching creates a donut shape, not a volcano. Apply 2 to 4 inches of mulch in a circle extending to the drip line or at least 3 feet from the trunk. Keep mulch 6 inches away from the trunk itself to prevent bark rot, pest infestations, and disease. Never pile mulch against the trunk, as this practice causes decay, encourages roots to grow into the mulch layer where they can girdle the tree, and creates hiding spots for rodents that gnaw bark. For established trees, a 3-foot diameter mulch ring is minimum; larger is better.
Is dyed mulch safe for gardens?
Modern dyed mulches use water-based, iron oxide or carbon-based colorants that are generally considered safe for plants and pets. However, the concern lies in the source wood. Some dyed mulches use recycled wood from pallets, construction debris, or treated lumber that may contain arsenic, creosote, or other chemicals. For vegetable gardens and areas where children play, choose natural undyed mulch or verify the dyed mulch is made from virgin wood chips. The dye itself is typically non-toxic, but source material quality varies significantly between brands.
What are rubber mulch pros and cons?
Rubber mulch offers several advantages: it lasts 10 or more years without decomposing, does not attract termites or carpenter ants, provides excellent cushioning for playgrounds, and requires no annual replenishment. However, significant downsides exist. Rubber mulch absorbs heat and can reach surface temperatures of 160 degrees Fahrenheit on hot days, potentially burning bare feet and stressing nearby plants. It does not improve soil health and may leach zinc and other compounds over time. Rubber mulch costs 2 to 3 times more than wood mulch initially, though long-term costs may balance out. It works best for playgrounds, sports surfaces, and non-planted areas.
Does mulch prevent weeds effectively?
A proper mulch layer significantly reduces weed growth but does not eliminate it entirely. At 3 inches deep, mulch blocks light from reaching weed seeds in the soil, preventing most germination. However, wind-blown seeds landing on top of the mulch can still sprout. For maximum weed prevention, remove existing weeds before mulching, apply mulch 3 to 4 inches deep, and maintain that depth with annual refreshment. Landscape fabric under mulch provides additional protection but can cause problems as it degrades and is not recommended for most plantings. Hand-pull any weeds that emerge promptly before they establish deep roots.
Should mulch touch my house foundation?
Keep all mulch at least 6 inches away from your home's foundation, siding, and any wooden structures. Mulch retains moisture and creates an environment conducive to termites, carpenter ants, and wood rot. Wood mulch in contact with your foundation provides a direct pathway for termites to access your home undetected. Many pest control professionals recommend a 12-inch mulch-free zone around foundations, filled instead with decorative stone or gravel. If mulch must be near the foundation, use cedar or cypress varieties and inspect the area regularly for pest activity. Never pile mulch against wooden deck posts, fence posts, or other structures.
Mulch Project Examples
Small Flower Bed
A typical front yard flower bed measuring 12 feet by 4 feet contains 48 square feet. At 3 inches deep, this requires: 48 x 3 / 324 = 0.44 cubic yards, or about 6 bags of 2 cubic foot mulch. Adding 10 percent for overage brings the total to 7 bags. This small project is ideal for bagged mulch, which you can transport in a standard vehicle.
Tree Ring Installation
Creating a proper mulch ring around a mature tree with a 4-foot radius covers approximately 50 square feet. At 3 inches deep with the center kept clear, you need roughly 0.4 cubic yards or 5 to 6 bags of mulch. Remember to maintain that critical 6-inch gap around the trunk, creating a donut shape rather than a volcano.
Large Landscape Renovation
A complete backyard landscape project with 600 square feet of beds requires significant material. At 3 inches deep: 600 x 3 / 324 = 5.5 cubic yards. With 10 percent overage, order 6 cubic yards of bulk mulch. At bulk prices of $30 per yard plus $75 delivery, total cost is approximately $255. The same coverage in bags would require 81 bags at $4 each, totaling $324 plus multiple trips to the store. Bulk delivery clearly wins for projects this size.
Mulching Tips
Best Timing for Mulching
Spring and fall are optimal mulching seasons. Apply spring mulch after soil warms to avoid trapping cold temperatures near roots. Late spring, once perennials emerge, prevents accidentally burying new growth. Fall mulching after the first hard frost protects perennial roots through winter and prevents frost heaving. Avoid mulching during the hottest summer months when soil is dry, as the mulch layer can prevent irrigation from reaching roots effectively.
Installation Best Practices
Edge beds first with a sharp spade to create clean lines and prevent mulch from spilling onto lawns. Remove existing weeds, including roots, before spreading new mulch. If refreshing existing beds, rake old mulch to break up any matted layers and incorporate oxygen. Spread mulch evenly using a rake, working from the back of beds toward the front to avoid trampling finished areas.
Avoid Volcano Mulching
Never pile mulch against tree trunks or plant stems. This common mistake traps moisture against bark, promoting rot and creating pest habitat. Proper mulching tapers from 3 to 4 inches at the outer edge down to nothing at the trunk, creating a slight depression or flat donut shape.
Calculating Delivery Needs
Standard dump truck beds hold 10 to 15 cubic yards, while pickup trucks safely carry about 2 cubic yards of mulch. If your project exceeds your vehicle's capacity, delivery is more practical. Most suppliers offer delivery for $50 to $100, making bulk delivery economical for orders of 3 cubic yards or more. Schedule delivery for a dry day when you can spread the mulch immediately to prevent the pile from heating up or developing mold.
The Calculation Formula
Cubic feet: Length (ft) x Width (ft) x Depth (inches) / 12
Cubic yards: Cubic feet / 27
Alternative formula: Square feet x Depth (inches) / 324 = Cubic yards
2 cu ft bags needed: Cubic feet / 2
These formulas calculate theoretical volume. Add 5 to 10 percent extra for settling, irregular shapes, and waste. Bulk materials settle during transport and after spreading, so a slight overage ensures complete coverage.
Recommended Depths by Material
- Mulch: 2-4 inches (3 inches recommended for weed suppression)
- Gravel (walkways): 2-3 inches over compacted base
- Gravel (driveways): 4-6 inches with proper base layer
- Topsoil (gardens): 4-6 inches for new beds
- Sand (pavers base): 1 inch screeded level
Material Weights per Cubic Yard
- Mulch: 400-800 lbs (varies by moisture content)
- Gravel: 2,800-3,000 lbs
- Topsoil: 2,000-2,200 lbs
- Sand: 2,600-2,800 lbs
Delivery tip: Order 5-10% extra to account for settling and irregular shapes. Most suppliers require minimum orders for delivery, typically 1-2 cubic yards.
Did you know?
- Mulch can reduce water evaporation by up to 25 percent, significantly lowering watering needs during hot summer months.
- Black mulch absorbs more heat from the sun and may damage plant roots near the surface, particularly in hot climates.
- Rubber mulch made from recycled tires lasts 10 or more years but does not add nutrients to soil like organic mulch does.
- Americans use over 20 million cubic yards of mulch annually, making it one of the most common landscaping materials.
- Cedar mulch can naturally repel some garden pests including certain beetles, moths, and cockroaches.