The Soil for Octagon Planter calculator computes the soil volume of an octagon planter based on the length of the sides (s) and the height (h). Use the interior dimension of the planter and a height to match the depth of soil desired. 
INSTRUCTIONS: Choose units and enter the following:
- (s) Length of Octagon Planter Sides (see diagram)
- (h) Height of planter or Desired Depth of Soil in Planter
Volume (V): The calculator returns the volume in cubic feet and the surface area in square feet. However, these can be automatically converted into compatible units via the pull-down menu next to the answer. The calculator also returns the equivalent volume of soil in number of soil bags of the following sizes:
- 1 ft3
- 1.25 ft3
- 2.5 ft3
- 8 quarts
- 32 quarts
- 64 quarts
IMPORTANT NOTE: To compute the amount of soil needed in the planter, use the interior dimensions of the container, and use the top diameter associated with how high you want to fill the container. If you wish to fill to the brim, it is the full inner height.
The Math / Science
The Octagon Planter formula calculates the volume of a octagon shaped planter. Enter the length of a side of the planter (s) and the (h) height of the interior of the container (see diagram), then this formula will provide the volume of the container. This answers the following questions:
- How much soil will my octagon planter hold?
- How much water will my octagon container hold?
- How much potting soil do I need?
If you do not intend to fill the container to the top, this formula will over estimate unless you use a height (h) that matches your expected top surface inside the container. Unless it's a very large container, and/or you are only using a small portion of the container, the overage should be small.
Potting Mix and Garden Soil
Potting Mix is combination of organic materials (e.g., peat moss, aged bark and pumice) but no soil (dirt) that is used in lieu of potting soil to improve drainage. Because potting mix has no soil, it tends to be lighter than potting soil and provides a more sterile medium for plants with fewer disease carrying agents. Potting mix is most commonly recommended for plants in containers, and potting mix is particularly desirable for starting seeds. Garden Soil is a gardening product sold that contains natural soil (dirt) comprised of mixture of loam, clay and sand. Garden soil is often used in raised gardens or planters as a healthy and easy medium for plants and seeds on top of the natural soil in one's yard. Garden Soil differs from Potting Mix in that garden soil contains real soil (dirt), where Potting Mix does not.
Potting Mix and Garden Soil Price Survey
vCalc conducts a periodic pricing survey from nationally advertised retailers for various materials. The current Garden Soil Price Survey sample information for Garden Soil and Potting Mix is as follows:
- Date: 5/14/24
- Store: Menards
- Garden Soil (1 ft3): $6.49
- Garden Soil (1.5 ft3): $7.49
- Garden Soil (2 ft3): $9.99
- Potting Mix (1.25 ft3): $13.71
- Potting Mix (2.5 ft3): $27.43
Always use local pricing! There is NO implied guarantee that these prices are available in your area or that products will be available. This pricing is purely provided for estimation convenience.
Raised Garden and Planter Soil Calculator
- Soil for Box Planter:
Computes the soil volume of a rectangular box shaped raised planter. - Soil for Circular Planter: Computes the volume and associated amount of soil for a circular planter (tapered or straight) based on the top diameter, base diameter and height.
- Soil for Tapered Rectangular Planter : Computes the volume and associated amount of soil needed for a tapered rectangular planter based on the top and bottom side lengths and height.
- Soil for Polygon Shaped Planter: Computes the volume of soil needed for a polygon shaped planter based on its shape (number of sides) and dimensions including the length of the sides and the height (depth).
- Soil for Triangular Planter: Computes the volume and associated amount of soil for a triangular shaped planter based on the side lengths (a, b, c) and (h) height.
- Soil for Hexagon Planter: Computes the volume and associated amount of soil for a hexagon shaped planter based on the length of the sides and height.
- Soil for Octagon Planter: Computes the volume and associated soil amount for an octagon planter based on the length of the sides and the height.
- Soil Needed for 3 Tier Raised Garden: Computes the amount of garden soil or potting mix needed for a three tier (step) raised garden based on the dimensions of the tiers.
- Cost of Soil: Computes the cost of a volume of soil base on unit price.
- Water Requirement to Prepare Soil: Estimates the minimum and maximum water range for plant growth to apply to initially moisten soil so that plants will not suffer from over or under watering.
- Conversions to Common Kitchen Units: This takes any volume measurement (you choose the units) and converts it into house-hold kitchen units. For example, 0.9 ft3 turns into 6 Gallons, 2 Quarts, 1 Pints, 1.5 Cups, 3 Tablespoons and 1.54 teaspoons. This is useful in measuring soil and nutrient supplements.
IMPORTANT NOTE: Use the interior dimension of the planters and a height to match the depth of soil desired.
Octagon Information
An octagon is a polygon with eight sides. It is a geometric shape characterized by having eight straight sides of equal length and eight angles, each measuring 135 degrees. The sum of the interior angles of an octagon is 1080 degrees. Octagons can come in various sizes and proportions but maintain the essential characteristic of eight sides.
Regular octagons have all sides and angles equal, while irregular octagons can have sides and angles of different lengths and measures. Octagons are commonly encountered in geometry and can be found in various contexts, such as in the design of stop signs, certain architectural elements, and decorative patterns.
Octagon Calculators
- Octagon Area: Area of regular octagon from side length.
- Octagon Side from Area: Side length of octagon from area.
- Octagon Radius from Area: Radius of octagon from its area.
- Octagon Radius from Side Length: Length of octagon side base on the outer radius.
- Octagon Side Length in a Square: Length of octagon side based on the width of the box or square containing it.
- Octagon Volume: Volume of a column based on side length and height.
- Octagon Column Surface Area: Surface area of column based on side length and height.
- Octagon Column Mass: Mass or weight of column based on side length, height and density.
- Octagon Planter Volume: Volume of soil and planting surface area in an octagon shaped planter based on dimensions.