Mel's Mix Ratio Calculator for Garden Beds

Calculator Inputs

Number of Beds

Length

Width

Depth

Dimension Unit

Waste Allowance (%)

Mix Mode

Compost Ratio Share

Peat / Coco Coir Ratio Share

Vermiculite Ratio Share

Compost Bag Size (ft³)

Peat / Coir Bag Size (ft³)

Vermiculite Bag Size (ft³)

Compost Bag Cost ($)

Peat / Coir Bag Cost ($)

Vermiculite Bag Cost ($)

Classic Mel's Mix uses equal one-third portions of compost, peat or coir, and vermiculite. Custom mode lets you test alternate proportions.

Example Data Table

Example Bed Size	Depth	Total Volume	Compost	Peat / Coir	Vermiculite
4 ft × 4 ft	0.5 ft	8.00 ft³	2.67 ft³	2.67 ft³	2.67 ft³
4 ft × 8 ft	0.5 ft	16.00 ft³	5.33 ft³	5.33 ft³	5.33 ft³
3 ft × 6 ft	0.75 ft	13.50 ft³	4.50 ft³	4.50 ft³	4.50 ft³
2 ft × 10 ft	1.0 ft	20.00 ft³	6.67 ft³	6.67 ft³	6.67 ft³

These examples use the classic equal-parts blend and do not include extra waste allowance.

Formula Used

1) Bed volume: Volume = Length × Width × Depth × Number of Beds

2) Waste allowance: Adjusted Volume = Base Volume × (1 + Waste % ÷ 100)

3) Ingredient share: Ingredient Volume = Adjusted Volume × (Ingredient Ratio ÷ Total Ratio)

4) Liters conversion: Liters = Cubic Feet × 28.316846592

5) Cubic yards conversion: Cubic Yards = Cubic Feet ÷ 27

6) Bag estimate: Bags Needed = Ceiling(Ingredient Volume ÷ Bag Size)

7) Estimated cost: Cost = Bags Needed × Price Per Bag

How to Use This Calculator

Enter the number of beds you want to fill.
Add the bed length, width, and fill depth.
Select the unit used for those dimensions.
Choose classic equal-parts mode or custom ratio mode.
Enter bag sizes for each ingredient supplier pack.
Optionally add bag prices to estimate shopping cost.
Click Calculate Mix to show the results above the form.
Use the CSV or PDF buttons to export your result summary.

FAQs

1) What is Mel's Mix?

Mel's Mix is a classic raised-bed blend made from equal parts compost, peat or coir, and vermiculite. It is designed to balance drainage, moisture retention, and nutrition.

2) Why does this calculator include waste allowance?

Waste allowance helps cover settling, handling loss, uneven bed corners, and minor overfilling. A small extra margin can prevent running short during installation.

3) Can I replace peat moss with coco coir?

Yes. Many gardeners use coco coir instead of peat. Coir is often chosen for sustainability and rehydration behavior, but it may change water retention slightly.

4) Why are bag counts rounded up?

You cannot usually buy partial bags. Rounding up ensures you have enough material to complete the bed without interruption.

5) Can I use custom ratios?

Yes. Custom mode lets you test alternate percentages for local conditions, ingredient availability, or personal growing preferences while keeping the total mix calculation accurate.

6) Which unit is best to use?

Use whichever unit matches your measurements. The calculator converts everything internally to cubic feet, then also shows cubic yards and liters for easier purchasing.

7) Does this calculator estimate cost accurately?

It provides a practical estimate based on entered bag prices and rounded bag counts. Taxes, shipping, and local price variation are not included.

8) Is this tool useful for multiple raised beds?

Yes. Enter the total bed count and the calculator scales the volume, ingredient requirements, bag counts, and estimated costs automatically.