Convert Inches to Feet and Tenths of Feet
Formula: Inches / 12 = Feet (Converts Inches Rain to Feet).
Enter inches in the cell labeled “Inches *” The cell labeled “Ft.” and ” X Ft. ” will automatically populate. The Convert Inches to Feet and Tenths of Feet calculation is used in each calculator below.
Calculate Runoff Volume in Gallons
Formula: Area Sq. Ft. * X Ft = Cubic Ft * 7.48 = Runoff Vol Gal.
There are six potential drainage area measurements that the user can input. First enter Inches of Rainfall in the cell labeled “Inches*” – the column labeled “X Ft.” will automatically populate. Next, enter the sq. ft. of each measured drainage area in the cells labeled “Area Sq. Ft.*” Enter zero for areas not needed. Columns are summed and totaled in the bottom row. Use Tot Cu. Ft to help design the shape and size of your rain garden. Use Total Gal to determine gallons of water your rain garden will treat.
Calculate Quantity of Compost
Formula: Yard Sq. Ft. * X Ft=Cubic Ft / 27=Cubic Yards Compost
First enter Inches of Mulch (6-8 inches recommended) in the cell labeled “Inches*” the cell labeled “X Feet” will automatically populate. Next enter the total area in sq. ft. to be landscaped in the cell labeled “Yard Sq. Ft.*” The remaining cells will automatically populate. Use Cubic Yards to determine the estimated amount of compost needed to mix with soils 14-16 inches deep.
Calculate Quantity of Mulch
Formula: Yard Sq. Ft. – Rain Garden Area=Mulch Area *Depth Mulch Ft.=Cubic Ft/ 27 = Cubic Yds. – 30% =Yds. Mulch Needed (We reduce the Cubic yards by 30% to account for the area taken up by plants.)
First enter Inches of Mulch (4 inches recommended) in the cell labeled “Inches*” – the cells labeled “Mlch Ft.” will automatically populate. Next enter sq. ft. of measured Yard area and Rain Garden Area in the cells labeled “YardSqFt.*” and “RG Sq.Ft.*” The rest of the cells will automatically populate. Use Cubic Yards -30% in the cell labeled “Less 30%” to determine cubic yards of Mulch needed.
Calculate Quantity River Rock
Formula: RainGarden SqFt.* Rock Depth Ft.= Cubic Ft./27
=Cu. Yds – 30% * Lbs per Yrd River Rk=Lbs. River Rk Needed.
First enter Inches of River Rock (3-6inch River Rock is ~3″ deep) in the cell labeled “Inches*” the cells labeled “Rk Dpth Ft. and Dth Ft.” will automatically populate. Next enter the measured Rain Garden area Sq. Ft. in the cell labeled “RG SqFt.*” The rest of the cells will automatically populate. Use Lbs. of Rock in the cell labeled “Lbs. Rk.” to determine the how many pounds of 3-to-6 inch River Rock.