The math is simple. One cubic yard of mulch covers about 160 square feet at two inches deep, or roughly 108 square feet at three inches. Measure your beds, multiply length by width, divide by the coverage number, and round up slightly for the uneven spots. A typical residential front bed package lands somewhere between three and eight yards.
Two to three inches is the whole target. Under two inches, weed seed gets enough light to germinate and you'll be pulling weeds by July. Over four, water struggles to reach the soil, roots start growing up into the mulch layer instead of down, and the bed goes anaerobic and starts to smell.
The most common and most damaging mistake is the mulch volcano — a cone piled up against a tree trunk. Bark is not designed to stay wet. Buried under mulch it stays damp, rots, and invites insects and disease, and the tree can quietly start girdling itself with roots that circle in the mulch. Pull mulch back two or three inches from every trunk and stem so you can see where the trunk flares into the ground.
Order matters as much as depth. Cut a clean spade edge first, then weed and cultivate what's inside the bed, then lay the mulch. Mulching over live weeds buys you about six weeks. And unless the bed is genuinely bare, you rarely need to strip last year's mulch — cultivate it and top-dress just enough to bring the total back to about three inches.
Color is preference, not performance. Black reads modern and shows plant color hard, brown is more forgiving as it fades, natural hardwood ages the most gracefully. What actually determines whether a bed still looks sharp in September is the edge and the depth, not the dye.