Raised garden bed planner

How to use the raised garden bed planner

Plan a raised garden bed from its inside dimensions, wall height and number of beds. The tool estimates soil volume, mix-specific bag counts, lumber cuts, screws and plant capacity for your selected crop.

1. Enter the inside length, inside width, wall height and number of beds.
2. Set the fill depth, bag size and soil mix percentages.
3. Choose the side board size and a stock board length, or leave least waste selected.
4. Select a crop to compare intensive, square-foot and row-garden capacity.
5. Use the soil, lumber, cut-list and plant-capacity results to prepare your order and layout.

What to enter

Inside length

Enter the bed's inside length in feet. The default is 8 ft.

Inside width

Enter the inside width in feet. The default is 4 ft. The tool notes that 4 ft or less lets you reach the middle from both sides.

Wall height

Enter the wall height in inches. The default is 11 in. The result rounds this up to whole boards.

Number of beds

Enter the number of beds. The default is 1; fractional entries are rounded to a whole number.

Fill depth

Enter the soil fill depth in inches. The default is 10 in. The interface suggests leaving 1–2 in below the wall top.

Bag size

Choose a bag size in cubic feet: 0.75, 1, 1.5, 2 or 3 cu ft. The default is 1.5 cu ft.

Topsoil

Enter the topsoil share as a percentage. The default is 60%.

Compost

Enter the compost share as a percentage. The default is 30%.

Aeration (perlite, bark)

Enter the aeration-material share as a percentage. The default is 10%.

Settling allowance

Add an allowance from 0% to 50% for settling. The default is 5%.

Side boards

Choose the board size for the bed sides. The default is 2x6; the selector shows each board's actual width.

Board length to buy

Choose a stock length in feet, or use Least waste (auto). The default is Least waste (auto).

Crop

Select the crop for the plant-capacity comparison. The default crop is lettuce.

Example: one 8 ft by 4 ft bed

Using the defaults gives 8 ft inside length, 4 ft inside width, 10 in fill depth, one bed, a 60% topsoil / 30% compost / 10% aeration mix, a 1.5 cu ft bag size and a 5% settling allowance. Growing area is 8 × 4 = 32 sq ft. Base soil volume is 8 × 4 × (10 ÷ 12) = 26.67 cu ft. With settling, the order volume is 26.67 × 1.05 = 28 cu ft, displayed as 1.04 cu yd. The mix components are 28 × 0.60 = 16.8 cu ft topsoil, 28 × 0.30 = 8.4 cu ft compost and 28 × 0.10 = 2.8 cu ft aeration material. At 1.5 cu ft per bag, those amounts round up to 12 topsoil bags, 6 compost bags and 2 aeration-material bags.

How the planner calculates the results

The soil estimate uses inside length × inside width × fill depth converted from inches to feet, then applies the settling allowance. It reports the adjusted volume in cubic feet and cubic yards. Each mix component is the adjusted soil volume multiplied by its percentage, and each component's bag count is rounded up to a whole bag using the selected bag size. The three mix shares must total 100%, and settling must be between 0% and 50%. For lumber, the planner uses the selected side-board size, wall height and bed dimensions to produce a stock-board quantity and cut list. Wall height is rounded up to whole boards. Least waste (auto) selects a stock length to reduce waste; a chosen stock length is used instead when selected. It also estimates 8 ft 4x4 posts and 3 in screws. Crop capacity is shown per bed in three views: intensive spacing, square-foot spacing and row-garden spacing.

Reading the results

Soil mix to order is the adjusted total for all beds, shown in cubic yards and cubic feet. The component boxes show the cubic feet and whole bags for each nonzero mix ingredient. The growing-area figure is the inside length × inside width for all beds. Lumber (per order) shows the board stock and quantity, 8 ft 4x4 posts, 3 in screws and the individual cuts. Select a crop to see its capacity per bed under intensive, square-foot and row-garden spacing. Use those figures as planning comparisons rather than combining the three methods.

Limitations and common mistakes

• The soil result depends on the fill depth you enter. It does not determine whether a particular bed design needs a different fill structure or material.
• The mix must add up to exactly 100%, and invalid sizes or percentages produce an error instead of a plan.
• The plant result is a capacity comparison for one selected crop per bed. It does not create a mixed-crop planting map or account for paths between beds.
• Lumber quantities and cuts are planning estimates based on the selected board and stock-length choices. Check your actual material dimensions and construction details before cutting.

Frequently asked questions