🌱 How to Calculate Garden Soil – Complete Guide

A soil calculator for raised garden beds eliminates guesswork and saves 40-50% on costs. Whether you’re using a potting soil calculator or calculating for vegetable gardens, accurate measurements are essential.

📐 Basic Calculation Formula

Example: For a 4×8 ft bed at 12 inches deep:

• 4 ft × 8 ft × 1 ft = 32 cubic feet
• = 0.59 cubic yards
• = 905 liters
• = approximately 16-22 bags (40L bags)

Garden Shape	Formula	Example
Rectangle	L × W × D	4×4×1 ft = 16 cu ft
Circle	π × (D÷2)² × Depth	4 ft diameter = 12.6 cu ft
Odd Shapes	Divide into rectangles	L-shaped = 2 rectangles

🛍️ How Many Bags Do You Need?

Bed Size	Depth	Volume	Bags (40L)
2×4 ft	12 in	8 cu ft (226L)	6 bags
4×4 ft	12 in	16 cu ft (453L)	12 bags
4×8 ft	12 in	32 cu ft (905L)	23 bags
4×10 ft	12 in	40 cu ft (1,132L)	28 bags

💡 Pro Tip: Add 10-15% extra soil for settling, compaction, and future top-dressing.

🌍 Soil Mix Ratio Customizer

The Ultimate Mix (works for 90% of plants):

Component	Percentage	Purpose	Per 100L
Topsoil	40%	Structure & nutrients	40L
Compost	30%	Organic matter	30L
Cocopeat	20%	Water retention	20L
Perlite	5%	Drainage	5L
Vermiculite	5%	Moisture & roots	5L

Alternative Mixes

• High Drainage: 40% topsoil, 35% sand, 25% compost (for clay areas)
• Water Retention: 35% topsoil, 35% compost, 20% cocopeat, 10% vermiculite (dry climates)
• Budget Mix: 50% topsoil, 50% homemade compost (cost-effective)

🌱 Plant-Specific Soil Needs

Plant	Depth	Best Mix Ratio	pH Goal	Volume/Plant
Tomatoes	24 in	40-30-25-5	6.2-6.8	18-20L
Garlic	8 in	50-25-15-10	6.0-7.0	10-12L
Herbs	6 in	30-35-25-10	6.5-7.0	8-10L
Root Vegetables	12 in	40-20-20-20	6.0-6.8	15-18L
Balcony Plants	5-8 in	30-25-30-15	6.5	5-10L

💰 Cost Comparison – India vs USA

Bag Size	India (₹)	USA ($)
40L Soil	₹180-220	–
50L Soil	₹240-300	–
2 cu ft Soil	–	$3-5
Bulk Soil/yard	₹2,000-3,000	$25-45

💡 Savings Hack: Buy bulk soil + make compost = 48% cheaper than bagged mixes.

🌍 Soil pH Calculator

Correct pH determines nutrient availability. Here’s what each crop needs:

Plant	Optimal pH	Problem if Wrong
Tomatoes	6.2-6.8	Below 6.0 = Calcium deficiency (blossom end rot)
Garlic	6.0-7.0	Above 7.5 = Poor bulb development
Herbs	6.5-7.0	Below 6.0 = Nutrient lock, yellowing
Peppers	6.0-6.8	Above 7.0 = Aluminum toxicity

How to Adjust pH

• To RAISE pH: Add dolomitic lime (1-1.5 lbs per 100 sq ft)
• To LOWER pH: Add elemental sulfur (0.5-1 lb per 100 sq ft)
• DIY Test: Mix soil with white vinegar. If it fizzes, pH is high.

📊 Water Retention Score

Formula: Base (6) + (Cocopeat % × 0.18) + (Vermiculite % × 0.07) − (Perlite % × 0.08)

Score	Rating	What to Do
1-3	Very Poor	Add compost or cocopeat
4-6	Below Average	Reduce perlite, add organic matter
7-8	Good	Perfect for most vegetables
9-10	Excellent	Ideal for herbs & balcony plants

🌍 Carbon Footprint – Eco-Friendly Gardening

Method	CO₂ per 100L	Savings
Store-bought soil	45 kg CO₂	–
Homemade mix	20 kg CO₂	25 kg (56% less)

For a 500L garden: Homemade mix saves 125 kg CO₂ = planting 20 trees annually!

📉 Soil Settling Predictor

Time Period	Settlement %	Action
Day 1-7	3-5%	Water thoroughly
Week 2-4	5-8%	Check depth
Month 2	10-12%	Begin top-dressing
Month 3	12-15%	Add 1-2 inches

Formula: Settling % = 12 − (Cocopeat % ÷ 230)

❓ Quick FAQ

🚀 Start Calculating Now!

Use the Garden Soil Calculator above to:

• ✅ Calculate exact soil volume needed
• ✅ Get plant-specific mix recommendations
• ✅ Estimate total cost (India & USA pricing)
• ✅ Check water retention scores
• ✅ See carbon footprint savings
• ✅ Predict soil settling
• ✅ Export PDF report
• ✅ Print shopping list

Perfect calculations = Healthier plants + 40-50% cost savings + Zero waste