Mulch Refresh / Top-Up Estimator
Estimate how much mulch you need to top up an existing bed back to a target depth — uses the difference between current and target depth, not full-depth install.
Limitations: Assumes a rectangular bed. Irregular beds should be broken into rectangles. Does not adjust for mulch that has decomposed and shrunk (compost yourself typically loses 30–50% depth per year).
What to do next: Avoid piling mulch against plant stems or tree trunks — keep a 2-in gap (no 'mulch volcanoes'). Top up annually in early spring or fall.
Planning estimate only. For bulk delivery, order ~10% extra for settling.