Construction
Mulch Annulus Calculator
Mulch volume for a ring (annulus) bed between two radii.
Free to use — no sign-up or login.
Area
ft²
Volume
ft³
Volume
yd³
Amortization schedule
| # | Date | Payment | Principal | Extra | Interest | Balance |
|---|---|---|---|---|---|---|
Annulus area is π(R² − r²). Outer 10 ft, inner 6 ft, and 3 inches give 201.06 ft² and 50.27 ft³.
A full circular bed is the mulch circle calculator.
The ring that is subtracted
The inner circle is the empty middle. Outer radius must be larger than inner radius or the page refuses the inputs.
Depth turns area into volume
The area is π(100 − 36). Three inches is a quarter of a foot, so the ring is 50.27 ft³.
Worked example: Annulus Mulch
Outer radius 10 ft, inner radius 6 ft, depth 3 in. Volume 50.27 ft³ and 1.86 yd³.
\[ A = \pi(10^{2}-6^{2}) \]
Frequently asked questions
What does the Annulus Mulch – Ring Between Two Radii measure?
Outer radius 10 ft, inner radius 6 ft, depth 3 in. Volume 50.27 ft³ and 1.86 yd³.
How many decimal places does Annulus Mulch – Ring Between Two Radii show?
Outer radius 10 ft, inner radius 6 ft, depth 3 in. Volume 50.27 ft³ and 1.86 yd³. Lengths, areas, volumes, and money use two decimals. Purchase counts are whole numbers.
Does Annulus Mulch – Ring Between Two Radii include waste?
Annulus mulch leaves the inner disk empty. It does not add bags on top of that ring.
Can Annulus Mulch – Ring Between Two Radii mix units?
No. Annulus Mulch – Ring Between Two Radii expects every input in the unit printed on its label.
Is Annulus Mulch – Ring Between Two Radii a code or structural check?
No. Annulus Mulch – Ring Between Two Radii is a quantity estimate. Local rules and site conditions stay outside the formula.
References
Assumptions and limitations
No bag count. The volume is only the ring, not the inner disk.