Raised Bed Calculator
Plan your raised garden beds with exact material quantities. Enter the bed dimensions and quantity to get soil volume in cubic yards, bags of soil mix, lumber boards, and total build cost.
Raised Bed Sizing Guide
The ideal raised bed width is 4 feet, allowing comfortable reach from both sides. Length is flexible but 8 feet is popular because it matches standard lumber lengths without cutting. Height depends on what you are growing and your physical comfort level. A 12-inch-tall bed provides enough depth for 90 percent of vegetables. Build beds 24 to 30 inches tall if you want to garden without bending over, or if your native soil has contamination you want to isolate from. Leave 2 to 3 feet between beds for pathway access and wheelbarrow clearance.
Building Materials Comparison
Cedar 2x6 boards are the gold standard: naturally rot-resistant, attractive, and available at most lumber yards at $8 to $15 per 8-foot board. Untreated Douglas fir costs less ($5 to $8 per board) but rots in 3 to 5 years. Galvanized steel raised bed kits have become popular and last decades without maintenance, running $100 to $300 for a 4x8 bed. Concrete blocks work well and cost about $1.50 each, but they raise soil pH slightly. Composite lumber resists rot and lasts 25-plus years but costs 2 to 3 times more than cedar.
Frequently Asked Questions
How deep should a raised bed be?
A minimum of 6 inches for herbs and lettuce, 12 inches for most vegetables, and 18 to 24 inches for root crops like carrots and potatoes. Deeper beds also work better on poor native soil.
What is the best soil mix for raised beds?
The classic mix is 60 percent topsoil, 30 percent compost, and 10 percent perlite or vermiculite. For square foot gardening, use equal parts peat moss, vermiculite, and compost (Mel's Mix).
What wood should I use for raised beds?
Cedar and redwood are naturally rot-resistant and last 10 to 15 years. Douglas fir lasts 5 to 7 years. Never use pressure-treated lumber for food gardens due to chemical leaching concerns.
How wide should a raised bed be?
Keep beds 3 to 4 feet wide so you can reach the center from either side without stepping on the soil. Length can be any dimension you have space for.