Calculate pebble mass, length, or width from coverage rate, using meters or feet and kg/m² or lb/ft² with any two inputs for landscaping projects.
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Pebble Coverage Formula
The pebble coverage calculator uses area and application rate to find the pebble mass needed. It can also work backward to find the missing length or width when you already know the available pebble mass.
- M = pebble mass required
- L = length of the coverage area
- W = width of the coverage area
- R = application rate, or mass of pebbles per unit area
If you leave pebble mass blank, the calculator multiplies length by width by the application rate.
If you leave length blank, the calculator divides the pebble mass by width and the application rate.
If you leave width blank, the calculator divides the pebble mass by length and the application rate.
The calculator converts all inputs to base units before calculating: meters, kilograms, and kg/m². It then converts the answer back to the unit you selected.
Common Pebble Application Rates
Application rate depends on pebble size, depth, compaction, and how even the surface is. Use these values as rough planning guides.
| Typical use | Approx. depth | Typical rate | Notes |
|---|---|---|---|
| Light decorative cover | 25 mm | 40 to 50 kg/m² | Best for low-traffic areas. |
| General garden coverage | 40 mm | 60 to 75 kg/m² | Common for beds and borders. |
| Path or heavier cover | 50 mm | 80 to 100 kg/m² | Useful where coverage needs to look full. |
Unit Conversion Reference
| Conversion | Value |
|---|---|
| 1 ft | 0.3048 m |
| 1 lb | 0.45359237 kg |
| 1 lb/ft² | 4.8824276 kg/m² |
| 1 kg/m² | 0.2048161 lb/ft² |
Example Calculations
Example 1: Find pebble mass
You have a garden bed that is 6 m long and 2 m wide. The application rate is 75 kg/m².
You need about 900 kg of pebbles.
Example 2: Find coverage length
You have 500 kg of pebbles. The area is 1.5 m wide, and the application rate is 75 kg/m².
The pebbles cover about 4.44 m of length at that width and rate.
FAQs
What application rate should you use for pebbles?
Use the rate that matches your desired depth and pebble size. A common starting value is 75 kg/m² for general garden coverage. Use a lower rate for a thin decorative layer and a higher rate for deeper coverage or larger pebbles.
Why does the calculator ask you to leave one field blank?
The calculator solves for one unknown value at a time. Enter any two of length, width, and pebble mass. Leave the value you want to calculate blank.
Should you order extra pebbles?
Yes, it is usually practical to allow extra material for uneven ground, settling, spreading loss, and edge areas. Adding about 5% to 10% is common for small landscaping jobs.
