Garden Exp Calculator: Estimate Costs & Yield

The Garden Expense Calculator estimates the total cost of starting and maintaining a vegetable or flower garden, including soil, seeds, plants, fertilizer, and water. You enter the garden area, soil depth, planting density, and local prices, and it returns a per-season cost breakdown and a cost-per-square-foot figure. This helps you budget realistically before you dig.

Formula

The calculator uses a simple additive model:

Total Cost = (Soil Volume × Soil Cost per cu yd) + (Area × Seed/Plant Cost per sq ft) + (Water Cost per month × Growing Months)

• Soil Volume (cu yd) = Area (sq ft) × Depth (in) ÷ 324 (since 1 cu yd = 27 cu ft and 1 ft = 12 in, so 27 × 12 = 324).
• Area = length × width of the garden bed, in square feet.
• Depth = how deep you fill or amend the soil, in inches.
• Soil Cost = price per cubic yard of bulk soil or compost, in dollars.
• Seed/Plant Cost = average cost per square foot for seeds or transplants, in dollars.
• Water Cost = monthly irrigation cost, in dollars.
• Growing Months = length of the growing season you pay water for, in months.

Worked Example

Using the default values (200 sq ft, 6 in depth, $30/cu yd soil, $1.50/sq ft seeds, $15/month water, 5 months):

1. Soil volume = 200 × 6 ÷ 324 = 1200 ÷ 324 = 3.70 cu yd (rounded).
2. Soil cost = 3.70 × $30 = $111.00.
3. Seed cost = 200 × $1.50 = $300.00.
4. Water cost = $15 × 5 = $75.00.
5. Total = $111.00 + $300.00 + $75.00 = $486.00.
6. Cost per sq ft = $486.00 ÷ 200 = $2.43.

The calculator shows $486.00 total and $2.43 per sq ft, matching the example.

When to Use This Calculator

Use this tool when planning a new garden bed, comparing raised beds vs. in-ground plots, or deciding whether to grow vegetables vs. buy them. It is also useful for budgeting annual garden expenses, estimating the cost of amending poor soil, or planning a community garden plot. The calculator assumes you are starting from bare soil or an empty bed; if you already have good soil, set soil depth to 0 and the soil cost term drops out.

How to Read the Results

The total cost is the main number—it is your upfront and seasonal spending. The cost per sq ft lets you compare different garden sizes or methods. The soil volume is a separate output because you may need to order that quantity from a supplier. If the total seems high, check the seed/plant cost: many gardeners spend more on transplants than seeds. Also, water cost can vary widely by region and rainfall; adjust the monthly figure to match your local rates.

Common Mistakes and Tips

• Unit mix-ups: Soil is sold in cubic yards, but depth is in inches. The formula converts correctly, but if you enter depth in feet, the result will be 12× too large. Always use inches.
• Forgetting amendments: Fertilizer, compost, and mulch are not included. Add them as a separate line item if needed.
• Overestimating yield: The calculator does not predict harvest value. A 200 sq ft garden can produce roughly 100–200 lbs of vegetables, but that depends on crop choice, climate, and care.
• Water cost is monthly, not total: If you water only 3 months, enter 3, not the whole year.

Limitations of the Formula

This is a planning tool, not a precise accounting system. Actual costs vary with local soil prices, seed quality, irrigation efficiency, and whether you use organic or synthetic inputs. The formula does not include tools, fencing, pest control, or labor. For a small garden, fixed costs like a shovel or hose can dominate, so add those separately. For a large garden, economies of scale may reduce per-sq-ft seed costs.

Alternatives to Buying Soil

If the soil cost seems prohibitive, consider composting kitchen scraps and yard waste to create free soil amendment. Many municipalities offer discounted compost. You can also start seeds indoors to reduce plant costs, or use drip irrigation to cut water bills. Raised beds require more soil per square foot than in-ground rows, so if budget is tight, choose in-ground or containers with less depth.

Frequently Asked Questions

How do I measure my garden area?

For a rectangle, multiply length by width in feet. For irregular shapes, break into rectangles and add them, or use an online area calculator. The result is in square feet.

What is a typical cost per square foot for a vegetable garden?

With seeds and basic soil, expect $1–$3 per sq ft per season. Using transplants, premium soil, and high water costs can push it to $5–$10 per sq ft. This calculator lets you input your own numbers to get a personal estimate.

Does this include the cost of plants or only seeds?

The seed/plant cost input is per square foot, so you can enter a blended rate. For example, if half the area uses $2/sq ft transplants and half uses $0.50/sq ft seeds, enter $1.25.

How much soil do I need for a raised bed?

Raised beds typically need 6–12 inches of soil. Use the soil volume output: for a 4×8 ft bed at 12 in deep, you need 4×8×12÷324 = 1.19 cu yd, about 32 cu ft.

Can I use this for a flower garden?

Yes, the formula works for any garden type. Flower beds often have higher plant costs and lower water needs, so adjust the inputs accordingly.

Why is my total so high?

Check the seed/plant cost per sq ft—it is the largest variable. Also verify the soil depth: 12 inches is deep for most vegetables; 6–8 is usually enough. Reducing depth or using cheaper seeds can cut costs significantly.

Related

• Vegetable Garden Row Calculator: Rows and Plants
• Raised Bed Calculator: Soil Volume and Fill Planning
• Pounds of Lime per Acre? Calculate the Right Amount

in area | Garden Area | sq ft | 200 | 0 | 100000
in depth | Soil Depth | in | 6 | 0 | 120
in soil_cost | Soil Cost | $/cu yd | 30 | 0 | 500
in seed_cost | Seed/Plant Cost | $/sq ft | 1.5 | 0 | 50
in water_cost | Water Cost | $/month | 15 | 0 | 500
in months | Growing Months | months | 5 | 1 | 12
out total | Total Cost | $ | (area * depth / 324 * soil_cost) + (area * seed_cost) + (water_cost * months) | 2
out per_sqft | Cost per sq ft | $/sq ft | total / area | 2
out soil_vol | Soil Volume | cu yd | area * depth / 324 | 1