Mulch calculator / Measured curved corner
Mulch Corner Bed Calculator
A curved corner is not a full circle. Measure its radius, choose how you measured the curve, then turn that area into mulch to order.
For your measured corners
Worked example: two 90° corners, each 6 ft from corner to edge. Replace these measurements.
11.78 cu ft
0.44 cu yd
Calculated from entered measurements, not from a photo. Depth is your choice, not a site recommendation.
Why this is not a rectangle
A 90° rounded corner is one quarter of a circle. Multiplying radius × radius gives a bounding square, not the planted area. The sector worksheet uses the radius and central angle to find the curved area first. If you measured the curved edge instead, it uses that length with the radius. Only then does it multiply by your chosen depth.
Two matching corners are added before bags are rounded up. That avoids buying a whole extra bag for each corner just because one bed ends in a fraction. The result is an ordering estimate, not a depth prescription. Look at the actual surface, existing mulch, plants and supplier package label before ordering.
Photos can show where a bed is, but they cannot supply reliable feet or inches. The source question that inspired this measurement workflow included guesses from pictures; none of those guessed dimensions is used here.
Method and limits
The University of Kentucky's sector formulas state that for a radius r and angle θ in radians, arc length is rθ and sector area is ½r²θ. With a measured arc s, this becomes area ½rs. Iowa State University Extension explains volume as area × depth, whole-bag rounding from a printed bag volume, and 27 cu ft per cu yd. These sources support the geometry and units, not the example depth or any product recommendation.
Use this only for a true circular sector with straight radial sides. It cannot infer hidden dimensions, slopes, irregular curves, plant-safe depth, taxes, or a supplier's bulk minimum. For a full round bed or bark clearance, use the tree-ring worksheet. For an uneven curve, sample measured widths with the irregular-width calculator. For several different bed shapes, measure each and use the multiple-bed worksheet.
Corner-bed questions
Can I estimate a corner bed from a photograph?
No. A photograph does not supply a reliable radius, angle or depth. Measure on site before using the worksheet.
Is the curved-edge length the same as the radius?
No. Radius is a straight line from the shared corner to the curve. Curved-edge length follows the arc along the front of the bed.
Do I round bags for every corner?
Not when the corners use the same material and bag size. The worksheet combines their measured volume first, then rounds the total up to whole bags.