Tree Well Calculator
— How Much Do You Need?

A tree well is the open area of ground that surrounds the base of a tree. In a lawn, it is usually defined by a circular border or edging that separates the tree's root zone from the surrounding grass. In urban or hardscaped settings, a tree well is often a cutout in pavement or a raised planter that gives a street or courtyard tree room to breathe and receive water. Filling a tree well with gravel or decorative stone is one of the most practical things you can do for your landscape. Unlike organic mulch, gravel does not break down, compact into a dense mat, or need to be replaced every season. It suppresses weeds, lets rainwater drain straight through to the roots below, and protects the trunk from lawn mower and string trimmer damage. Gravel also holds its appearance through rain, wind, and foot traffic in a way that wood mulch simply cannot match. From a design standpoint, a clean gravel tree well creates a finished, intentional look that sets off the tree and ties the landscape together. Whether you are a homeowner refreshing your front yard or a landscaper working on a commercial property with dozens of trees, gravel is a low-maintenance, long-lasting solution that pays off quickly.

Pea gravel is the most popular choice for tree wells, and for good reason. Its small, smooth, rounded stones, typically around three-eighths of an inch, sit loosely enough that water passes through freely, which is exactly what tree roots need. Pea gravel comes in warm natural tones that look good in just about any landscape setting, and it is comfortable to walk on or work around. Small river rock, usually in the three-quarter-inch to one-inch range, is another excellent option. It has a slightly bolder, more natural look and drains just as well as pea gravel. River rock tends to stay in place a little more firmly, which makes it a good choice if the tree well is near a high-traffic area or if you want a more defined, structured appearance. Decomposed granite and crushed granite are popular in drier climates and formal landscapes. These materials pack together slightly more than rounded stone, which can give the well a smoother, more polished finish. Just be mindful that finer, tightly packed materials can restrict airflow to the roots over time if applied too deeply. As a general rule, you want a material that is permeable, stable, and proportionate to the size of the tree well. If you are unsure which material fits your project and your region, the Hello Gravel team is happy to help you choose before you place your order.

For most tree wells, a small stone in the three-eighths-inch to three-quarter-inch range hits the sweet spot. Stones in this size range are large enough to stay put and resist washing out during heavy rain, but small enough to lay flat and look intentional rather than chunky. They also allow water to filter through the gaps between stones and reach the root zone below. Very fine materials like sand or stone dust are not a good fit for tree wells. They tend to compact over time, forming a layer that sheds water rather than absorbing it, and they can crust over in dry weather. That works against the whole purpose of a tree well. On the other end, large decorative rock in the one-and-a-half-inch-plus range can work visually, but it shifts underfoot, leaves wide gaps that invite weeds, and can be tricky to work around when you are maintaining the tree. It is more at home in a dry creek bed or boulder feature than in a close-fitting tree well. If you are comparing options and want a recommendation based on your specific landscape, reach out to the Hello Gravel team or use the product selector on the site. Getting the grade right before you order is much easier than correcting it after a truckload is in your driveway.

A depth of two to three inches is the standard recommendation for a gravel tree well. That is enough to suppress weeds, look full and finished, and hold its position through normal weather. Going deeper than four inches is not advisable because a thick, heavy layer of stone can restrict oxygen from reaching the roots and stress the tree over time. To calculate how much material you need, start with the area of your tree well. For a round well with a six-foot diameter, the area is roughly 28 square feet. At a depth of three inches, that single well requires less than one cubic yard of material on its own. One tree well is a small footprint, but most projects involve more than one tree. A property with ten trees, each with a six-foot-diameter well, adds up to around 280 square feet of coverage, and a larger commercial or residential project with mature trees and wider wells can grow quickly from there. Because Hello Gravel delivers by the truckload, this material is best suited for projects where you are filling multiple tree wells, combining a tree well project with other landscaping work like pathways or garden beds, or working on a commercial or HOA property where volume is a natural fit. The Hello Gravel calculator will give you a precise quantity estimate once you enter your dimensions, and it takes the guesswork out of figuring out how many tons or cubic yards to order.

The single most important thing to remember during installation is to keep the gravel away from the trunk. Leave at least a three to four inch gap between the edge of your gravel layer and the bark of the tree. Piling stone, mulch, or any material directly against the trunk traps moisture against the bark and invites disease, rot, and pest damage. This mistake is so common it has a name in the landscaping world: volcano mulching. You want the area around the trunk to remain open and dry at ground level while the rest of the well is filled. Before you spread any gravel, it is a good idea to lay a permeable landscape fabric or weed barrier over the soil. This keeps weeds from pushing up through the stone without blocking water from reaching the roots. Cut the fabric to fit the well area and leave that clearance zone open around the trunk. Once your fabric is in place, spread the gravel evenly to your target depth of two to three inches. Rake it level so there are no mounded spots. If you have edging or a border in place, make sure the gravel sits just below the top edge so it does not spill out onto your lawn or pavement. After spreading, a light watering helps the stones settle into place and shows you if any areas need to be topped off. From there, the maintenance is minimal.