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Surface Area Measurements

Surface Area Measurements

Have you ever applied pesticides or fertilizers to your lawn?  When you went to the garden center to purchase the product, did you know how much to purchase?  Were you confused on the amount to use as you applied it to your lawn?  If so, one way to assist in the appropriate use of these products is to know the surface area (square feet) of your turf.  Unfortunately, most people in Texas have never made this calculation.  It’s a very easy task and the information obtained is vital in your turf management program.  By not knowing the surface area, you could be applying too much or too little of the product.  Furthermore, you could be damaging both the turf and the environment.

As stated earlier, the steps in calculating the number of square feet in your lawn is relatively easy.  First, draw a sketch (diagram) of your lawn surrounding your home.  Try to incorporate the various angles and circular patterns in your drawing.  Also, be sure to label each area (i.e. front lawn, northeast landscape bed, front of house, oak tree, etc..) so that you know the exact area that you will measure.  Next, determine the exact areas (i.e. squares, rectangles, triangles, trapezoids, circles, etc..) that will be measured and label them with “letters” (i.e. A, B, C, etc..).  Now, it is time to measure!  You will need to use some type of measuring device so that you can determine the number of “feet” for each straight line.  Some use roller wheels, tape measures, or the roll-up measuring tapes.  It doesn’t really matter which type you use as long the measurement is accurate.  On your sketch, write down each measurement.  After you have completed the measuring procedure, it is now time to make the correct calculations to determine the square feet for each “lettered” area on your sketch.  Once you have done this, you can then add up all the areas to get your grand total.

It is extremely important to use the proper formula to determine the surface area of your turf.  Below is a list of shapes and the correct formula that corresponds with it:

Areas of: rectangle or square = length x width
  trapezoid  = (parallel sides A + B) / 2   x  height
  triangle   = (base x height) / 2
  circle   = (radius x radius) x 3.14
  oval   = (length x width) x 0.8

Measurement Equivalents:

1 square inch (in.2 ) =  6.451626 cm2   =  0.0069444 ft2
1 square foot (ft2) =  144 in2  =  0.111 yd2   =  0.0929 m2
1 square yard (yd2) =  9 ft2   =  1,296 in2   =   0.83613 m2
1 hectare (ha)  =  2.471 acres
1 acre = 43,560 ft2 =  4,840 yd2   =  4,046.873 m2  =  0.404687 ha  =  0.0015625 mi2