Square Feet: There are 4 planters that measure 6' long (length) by 4' wide (width) and there are 2 planters that measure 4' long (length) and 4' wide (width). NOTE: The math below does not account for the potato planter as it is filled continuously as the plants grow.
- 6' x 4' = 24 sq ft x 4 (planters) = 96 sq ft (subtotal #1)
- 4' x 4' = 16 sq ft x 2 (planters) = 32 sq ft (subtotal #2)
- 96 sq ft (subtotal #1) + 32 sq ft (subtotal #2) = 128 sq ft (total #1)
Unfortunately, this information is, basically, only useful for the purpose of communicating the sheer size of your garden when speaking with friends, neighbors, family, and colleagues.
Cubic Feet: To find cubic feet, you need to add the dimension of depth. So, say I wanted 3" of dirt in each planter. To get to cubic feet, I simply multiply L x W x D. However, I first have to convert any dimension that is measured in inches over to feet. As a result, I need to divide my depth (3") by 12". Therefore, 3" / 12" = 0.25'.
- 6' x 4' x 0.25' = 6 cu ft x 4 (planters) = 24 cu ft (subtotal #3)
- 4' x 4' x 0.25' = 4 cu ft x 2 (planters) = 8 cu ft (subtotal #4)
- 24 cu ft (subtotal #3) + 8 cu ft (subtotal #4) = 32 cu ft (total #2)
OK, so now we're getting somewhere. We now know that we have 32 cu ft (total #2) in the six raised planters.
Cubic Yards: Now that I have cubic feet, I need to divide total #2 (32 cu ft) by the number of cubic feet in a cubic yard, which is 27.
- 32 cu ft / 27 = 1.19 cu yds
If I round up the purchase to make sure I have enough dirt due to settling, I'll purchase 1.5 cu yds of dirt. Well, technically I won't be purchasing the dirt as the dirt is already available back at my house... that's a completely different problem
Amount of Pathway Rock Needed
Calculating the amount of rock needed is a bit more complex because, while the pathways are contiguous, you have to add up the length and width and depth (2") for each pathway. What I did for this calculation was to determine the vertical paths (4) and the horizontal paths (2)... look at the image above again and you should quickly see what I am referring to. Here's what the math looks like for that:
- Overall Pathway Depth: The entire rock path will be 2" deep. So I need to convert that to feet --> 2" / 12" = 0.16' (D).
- Overall Pathway Width: The path is 1' 6" all the way around for both the vertical and horizontal paths. As a result, I need to convert the 6" in the 1' 6" dimension to feet. That's easy --> 6" / 12" = 0.5', then simply add the 0.5' to the original 1' dimension --> 1.5'. The 1.5' (W) dimension will be used hereafter.
- Vertical Pathway Length: Each vertical path in the image is 4' long (L1).
- Horizontal Pathway Length: I have two pathways that measure 13' 6" in length. Just like the Overall Pathway Width, I need to convert the 6" to feet. Since we know that number is 0.5', I'll just that to the original 13' dimension which gives me 13.5' (L2).
Calculations:
- Vertical --> 4' x 1.5' x 0.16' = 0.96 cu ft x 4 (vertical paths) = 3.84 cu ft / 27 = 0.14 cu yds
- Horizontal --> 13.5' x 1.5' x 0.16' = 3.24 cu ft x 2 (horizontal paths) = 6.48 cu ft / 27 = 0.24 cu yds
- Total Rock Needed: 0.14 cu yds (vertical paths) + 0.24 cu yds (horizontal paths) = 0.38 cu yds total
Rounding up the 0.38 cu yds indicates that I'll need about 1/2 yard of rock.
Easy peezy... now you know how to estimate.