Garden Size Calculator

This garden size calculator measures the real growing area of your garden in square feet. It handles rectangles, circles, L-shaped plots and irregular shapes, and it subtracts the space taken by paths, which is the step most people skip. The result shows the total area, the area lost to paths, the share left for growing, and what that space equals in standard 4-by-8-foot beds. Use the growing area, not the outside measurements, for every other number you plan with, from plant counts to soil and compost.

How to use the garden size calculator

1. Choose the shape. Rectangle covers most gardens and beds. Use circle for round plots, L-shape for a garden made of two rectangles, and irregular for curved or tapering plots.
2. Enter the measurements in feet. For an irregular garden, enter the length plus the width at each end and in the middle. The calculator averages the widths.
3. Enter the paths. Add up the length of every path inside the garden and enter the path width. Enter 0 if you have no paths, for example in a single raised bed.
4. Read the growing area. This is the number to carry into the other tools.

Area formulas for common garden shapes

All garden area calculations come down to a handful of shapes. Complicated plots are just combinations of these.

• Rectangle or square: length × width.
• Circle: 3.1416 × radius × radius, where the radius is half the diameter.
• Triangle: base × height ÷ 2.
• L-shape: split it into two rectangles that do not overlap and add their areas.
• Trapezoid or tapering plot: length × the average of the two end widths.
• Irregular shape: length × the average of several widths measured along it.

Growing area = total area − (total path length × path width)

Worked example: a backyard vegetable plot

A plot measures 20 feet by 12 feet, a total of 240 square feet. A 2-foot-wide path runs down the middle for the full 20 feet, splitting it into two long beds. The path takes 40 square feet, leaving 200 square feet for growing, or 83 percent of the plot. That is the same growing space as about six 4-by-8-foot raised beds.

Worked example: a round herb garden

A circular herb garden 12 feet across has a radius of 6 feet, so its area is 3.1416 × 6 × 6 ≈ 113 square feet. If two 2-foot paths cross through the center, each 12 feet long, the paths cover about 2 × 12 × 2 = 48 square feet. Because the paths overlap in the middle, the true figure is slightly less, about 44 square feet. That leaves roughly 69 square feet of planting.

Worked example: an L-shaped bed

A bed wraps around a patio corner. One leg is 20 feet by 6 feet and the other, measured from the inside corner, is 10 feet by 6 feet. The total area is 120 + 60 = 180 square feet. Measuring the second leg from the inside corner avoids counting the corner square twice.

Worked example: a curved border

A border is 20 feet long. It is 8 feet wide at one end, 12 feet in the middle and 10 feet at the other end. The average width is (8 + 12 + 10) ÷ 3 = 10 feet, so the area is about 200 square feet. More width measurements give a more accurate average for very wavy edges.

How to measure a garden accurately

• Use a long tape. A 100-foot tape is ideal for whole yards. Paced measurements are often off by 10 percent or more.
• Measure inside edges. For framed beds, measure inside the boards. Lumber takes up about 1.5 inches on each side.
• Convert inches to decimal feet. Divide by 12. Six inches is 0.5 feet and nine inches is 0.75 feet.
• Check right angles. To lay out a square corner, use the 3-4-5 method: measure 3 feet along one side and 4 feet along the other. When the diagonal between those points is exactly 5 feet, the corner is square.
• Sketch it. Draw the plot on paper or graph paper and write each measurement on the sketch. It makes splitting odd shapes much easier.

Planning paths

Paths are easy to underestimate. In a typical vegetable garden with beds and paths, paths often take up a quarter to a third of the total area. Planning them deliberately keeps that share sensible while still giving you comfortable access.

A useful layout is one wider main path for barrows and carts, with narrower side paths between beds. Covering paths with wood chips, straw or gravel keeps them mud-free and suppresses weeds. The mulch calculator works out how much material you need for paths.

Bed width and reach

The most common raised bed and planting bed width is 4 feet, and it is not arbitrary. Most adults can comfortably reach about 2 feet into a bed, so a 4-foot bed can be worked from both sides without stepping on the soil. Beds against a fence or wall, reachable from only one side, should be no more than 2 to 3 feet wide. For children or gardeners with limited reach, 3-foot-wide beds are easier.

Bed length matters less, but very long beds tempt people to step across them rather than walk around. Many gardeners keep beds to 8 to 12 feet, or put a crossing path in the middle of longer ones.

How big should a vegetable garden be?

There is no single right size. It depends on what you want to grow, how much time you have and whether you plan to preserve food. Many guides suggest something in the range of 100 to 200 square feet of growing space per person for fresh eating through the season, and more if you want to can or freeze. Sprawling crops such as winter squash, melons and corn take far more space than salad greens and herbs.

For a first garden, smaller is usually better. One or two 4-by-8-foot beds, or a 10-by-10-foot plot, is enough to learn the basics without the garden becoming a chore. It is easier to expand a garden you enjoy than to rescue one that has been overrun by weeds.

Once you know your growing area, use the plant spacing calculator to see how many plants of each crop will fit, and the plant database to compare how much space each crop needs.

Using growing area in other calculations

The growing area is the starting point for almost every other garden calculation.

• Soil and compost: multiply the growing area by the depth you want. The soil calculator and compost calculator do this for you.
• Plants and seeds: plant counts depend on the bed area, not the plot including paths. See the seed quantity calculator.
• Water: a common target is about an inch of water per week. Over 100 square feet, that is roughly 62 gallons.
• Fertilizer: product labels and soil test recommendations are usually given per 100 or per 1,000 square feet.

Unit conversions

US gardens are measured in feet, but you may need other units for products or for comparing with sources from other countries.

• 1 square foot = 144 square inches = about 0.093 square meters.
• 1 square yard = 9 square feet.
• 1 acre = 43,560 square feet, roughly a square 209 feet on each side.
• 1 square meter = about 10.76 square feet.

The calculator shows square meters for every result and acres for larger plots.

Common mistakes

• Using outside dimensions. Planning plants and soil for the whole plot, paths included, overestimates by a quarter or more.
• Counting overlapping areas twice. When splitting an L-shape, measure the second leg from the inside corner.
• Forgetting shade. Part of a plot shaded by a tree or building for most of the day may be poor growing space for vegetables, even if it counts as area.
• Starting too big. A smaller, well-kept garden usually produces more than a large neglected one.

Sun, slope and where to put the garden

Area is only part of the picture. Before committing to a site, check three things that affect how much of that area is actually good growing space.

• Sunlight: fruiting vegetables such as tomatoes, peppers, squash and beans need at least six hours of direct sun, and they do best with eight or more. Leafy greens and many herbs manage with four to six. Watch the site across a whole day, ideally in late spring, because the sun’s path changes through the year and trees leaf out.
• Slope and drainage: a gentle slope is fine and can help cold air drain away, but water should not collect on the site after rain. Low spots that stay soggy are better used for raised beds, which lift roots above wet ground.
• Water access: a garden close to a hose bib gets watered far more reliably than one at the far end of the yard. Measure the distance and make sure a hose will reach comfortably.

If only part of your plot gets full sun, measure that part separately. Use it for fruiting crops and give the shadier part to greens, herbs or shade-tolerant flowers.

Planning to expand later

Many gardens start small and grow. If you think you may expand, a little planning now saves work later. Orient beds so new ones can be added in line, keep paths at a consistent width, and leave room for the main path to extend. Measuring the whole available space now, even if you only plant part of it, lets you plan where future beds and paths will go.

When you do expand, recalculate the growing area and use it to update your plant, soil and watering plans. The raised bed soil calculator handles new beds, and the mulch calculator handles the new paths.

Raised beds or in-ground beds?

The growing area is the same either way, but the cost and work differ. Raised beds need lumber or kits and a lot of soil, but they warm sooner in spring, drain well and are easier on the back. In-ground beds cost much less to start but depend on the quality of your existing soil, which usually needs compost added. Many gardens mix both: raised beds for vegetables near the house, and in-ground beds for larger crops such as squash and corn.

Frequently asked questions