How do I calculate how much soil I need for a raised bed?

Multiply the length by the width by the depth (in feet) to get cubic feet. Divide by 27 for cubic yards. Our Raised Bed Soil Calculator does this automatically and also gives you a recommended soil mix recipe.

How many boards do I need to build a raised bed?

It depends on your bed dimensions and board size. Our Raised Bed Lumber Estimator calculates exact board count and board-feet for any size bed, and lets you compare costs across wood species like cedar, pine, and white oak.

How much does it cost to build a raised bed?

A typical 4x8 raised bed costs $80–$300 depending on wood species, soil mix, and hardware. Our Raised Bed Cost Calculator breaks down lumber, soil, and hardware costs so you can budget accurately before you buy.

When should I plant based on my frost date?

Most vegetables should be planted after your last spring frost date. Our Planting Dates Calculator lets you enter your frost date and shows planting windows for 30+ common vegetables, including when to start seeds indoors.

How many plants fit in a raised bed?

Spacing depends on the plant variety. Our Plant Spacing Calculator uses square-foot gardening principles to tell you exactly how many plants fit in any size bed, with recommended in-row and between-row spacing.

How much water do raised beds need?

Raised beds typically need 1–2 inches of water per week, but this varies by climate, plant type, and season. Our Watering Guide Calculator gives you a personalized watering schedule based on your bed size and local conditions.

How much mulch do I need for my garden?

For most gardens, 2–3 inches of mulch depth is ideal. Multiply length × width × depth (in feet) and divide by 27 for cubic yards. Our Mulch Calculator does this instantly and converts the result to bags or cubic yards.

What is the ideal carbon-to-nitrogen ratio for compost?

The ideal C:N ratio for active composting is 25–35:1. Below 20:1 (too wet/slimy) means too many greens; above 35:1 (too dry/slow) means too many browns. Our Compost Ratio Calculator shows your current ratio and suggests exactly what to add to reach the ideal range.

How long does it take vegetables to grow?

Days to harvest varies widely — lettuce is ready in 30–45 days while winter squash takes 80–100 days. Our Harvest Estimator lets you enter a planting date and crop type and shows you an estimated harvest date.

How much food can a raised bed produce?

A 4x8 raised bed can produce 20–40 lbs of vegetables per season depending on what you grow. Tomatoes, zucchini, and beans are among the highest yielding. Our Crop Yield Calculator estimates pounds per season by crop and bed size.

When should I start seeds indoors?

Most seeds should be started 6–10 weeks before your last frost date. Our Seed Starting Calculator counts back from your frost date and shows you the ideal start window for each crop so seedlings are ready to transplant at the right time.

What size raised bed is best for wheelchair access?

ADA guidelines recommend a maximum reach depth of 24 inches (610mm) from a seated position. Our Accessible Garden Bed Calculator helps you size beds for comfortable wheelchair access, including height and width recommendations based on mobility needs.

Garden Calculators

Free tools to plan your raised bed garden — soil volume, lumber costs, planting dates, and more. No signup required.

Raised Bed Soil Calculator

How much soil do you need? Enter your bed dimensions and get exact cubic feet, cubic yards, and bag estimates.

Length (ft)

Width (ft)

Depth (in)

Bed shape

For soil mix recipes, see our Raised Bed Soil Mix Guide.

Formula: volume = length × width × (depth ÷ 12). Mix proportions based on University of Maryland Extension raised bed guidelines.

Raised Bed Lumber Estimator

Calculate exactly how much wood you need, plus estimated cost by species.

Bed length (ft)

Bed width (ft)

Bed height (in)

Wood species

Board thickness

Compare wood species in our Best Wood for Raised Beds guide. Or buy pre-built beds and skip the math.

Board-foot formula: linear ft × thickness × width ÷ 12. Species lifespan data from the USDA Forest Products Laboratory.

Raised Bed Total Cost Calculator

Estimate the full cost of a raised bed — lumber, soil, hardware, and optional extras.

Length (ft)

Width (ft)

Depth (in)

Wood

Soil source

Full cost breakdown: What Does a Raised Bed Really Cost?

Lumber pricing based on retail market averages from Random Lengths lumber price indices. Soil costs estimated from regional bulk supplier surveys. Prices vary by region and season.

Planting Date Calculator

Enter your USDA zone and find out when to start seeds, transplant, and direct sow your favorite crops.

USDA Zone

Crop

For a full zone guide, see Spring Planting by Zone.

Frost dates from the USDA Plant Hardiness Zone Map. Crop timing from state cooperative extension planting calendars.

Plant Spacing Calculator

How many plants fit in your raised bed? Select a crop and bed size to see the layout.

Bed length (ft)

Bed width (ft)

Crop

For layout ideas, see What to Plant in a 4×8 Raised Bed.

Spacing recommendations from UMass Extension Vegetable Program and the square-foot gardening method (Mel Bartholomew, 1981).

Raised Bed Watering Calculator

How much water does your raised bed need? Depends on size, soil, and climate.

Bed length (ft)

Bed width (ft)

Climate

Bed is mulched (reduces water by ~40%)

See: Raised Bed Watering Guide · Cut Water Use by 50%

Water requirements based on UC ANR irrigation guidelines for home vegetable gardens. Mulch reduction factor (~40%) from University of Florida IFAS Extension.

Mulch Calculator

How much mulch do you need to cover your beds? Enter dimensions and desired depth.

Area length (ft)

Area width (ft)

Depth (inches)

Mulch type

See: Mulching Raised Beds Guide

Volume formula: length × width × (depth ÷ 12). Depth recommendations from Cornell Cooperative Extension (3" for weed suppression, 4–6" for pathways).

Compost Ratio Calculator

Get the right carbon-to-nitrogen ratio for fast, healthy compost. The ideal is 25-30:1 (browns to greens).

What are you composting?

See: Build a 3-Bin Compost System · Compost Tea Guide

C:N ratio targets (25–35:1) from the US Composting Council and USDA NRCS composting guidelines. Material C:N values from Cornell Composting Science & Engineering.

Harvest Date Estimator

When will your crops be ready to pick? Enter your planting date and crop type.

Planting / transplant date

Crop

See: Extend Harvest into December

Days-to-maturity ranges from University of Minnesota Extension and seed supplier data. Ranges reflect variation across varieties.

Crop Yield Estimator

How much food will your raised bed actually produce? Realistic yield estimates per plant.

Crop

Number of plants

Growing conditions

See: Crop Yield Guide · Maximum Harvest, Minimum Cost

Yield estimates based on USDA Economic Research Service home garden yield data. Grocery value from USDA retail average prices.

Seed Starting Schedule Generator

Enter your last frost date and get a complete seed starting countdown — when to sow, transplant, and direct seed.

Your last frost date

For full zone guides, see our Spring Planting Guide.

Indoor seed starting lead times from University of Minnesota Extension. Timing verified across multiple state extension service calendars.

Accessible Raised Bed Sizer

Design a wheelchair-accessible or standing-height raised bed with the right dimensions for comfortable, safe gardening.

Access type

Desired length (ft)

Full design guide: Accessible Garden Design for Wheelchair Users. Or browse our accessible raised beds.

Dimensions based on ADA Standards for Accessible Design (§1002.14) and USDA accessible garden guidelines. Reach ranges informed by occupational therapy standards.

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Garden Calculators

Raised Bed Soil Calculator

Recommended soil mix

Raised Bed Lumber Estimator

Raised Bed Total Cost Calculator

Planting Date Calculator

Plant Spacing Calculator

Raised Bed Watering Calculator

Mulch Calculator

Compost Ratio Calculator

What are you composting?

Harvest Date Estimator

Crop Yield Estimator

Seed Starting Schedule Generator

Accessible Raised Bed Sizer

Get the free planting calculator PDF