HELPFUL FORMULAS AND ESTIMATES
FOR BOULDERS AND LEDGE ROCK

AREA(FACE FOOT)=Length X Width(Height)
DEPTH IN FEET=Depth in inches divided by 12
CUBIC FEET REQUIRED=Length X Width(Height) X Depth
CUBIC YARDS REQUIRED=Cubic feet divided by 27
CIRCLE AREA=3.14 X Radius Squared
CIRCLE CIRCUMFERENCE=3.14 X Diameter
TRIANGLE AREA=1/2 of Base x Height

***One Cubic Yard = 27 Cubic Feet
***One Ton = 2000 pounds
***One Ton of Construction Aggregate = 3/4 of a cubic yard

TONNAGE REQUIRED=Cubic Feet X Pounds per Cubic Foot divided 
by 2000

APPROXIMATE WEIGHTS PER CUBIC FOOT:
***Michigan Granite Boulders:170 pounds per cubic foot
***Michigan Limestone:155 pounds per cubic foot
***Canadian Limestone:165 pounds per cubic foot

***Michigan Grindstone:136 pounds per cubic foot



MICHIGAN BOULDER COVERAGE:
SIZE
APPROXIMATE
WEIGHTS
APPROXIMATE 
FACE FEET PER TON

4"-8"
20-60lbs.
30-50
4"-12"
20-100lbs.
18-19
8"-18"
100-200lbs.
15-16
12"-24"
125-250lbs.
13-14
18"-30"
205-530lbs.
11-12
24"-36"
250-1100lbs.
9-10
30"-42"
530-2000lbs.
7-8
36"-48"
1100-2800lbs.
6-7


APPROXIMATE BOULDER WEIGHTS:
SIZE
WEIGHT
12"
100lbs.
14"
125lbs.
18"
205lbs.
24"
253lbs.
30"
530lbs.
36"
1100lbs.
48"
2800lbs.

***One cubic yard of 4"-12" oversize cobblestone
weighs approximately 3,200 pounds.


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