Mulch, Soil & Gravel Guides on CalculatorMulch

How Much Mulch Do I Need? The 27 Rule Explained

Thu, 06 Aug 2026 00:00:00 +0000

Why does dividing by 27 turn feet into yards?

Because a cubic yard is a cube three feet on every side, and 3 × 3 × 3 = 27 cubic feet. That is the entire origin of the number. Bulk landscape material is priced by the cubic yard, bagged material is labelled in cubic feet, and every mulch question is a conversion between those two units.

Written out, the rule is:

How Deep Should Mulch Be? 2, 3 or 4 Inches

Thu, 06 Aug 2026 00:00:00 +0000

What depth does mulch actually need to be?

Three inches, for the ordinary case of a planting bed with shrubs and perennials in it. The number is not arbitrary: it is where two curves cross. Weed suppression improves steeply from zero to about three inches and then flattens out, because by three inches you have already blocked the light. Soil health gets worse steeply after about four inches, because gas exchange falls off. Three sits on the good side of both.

Bagged vs Bulk Mulch: Which Is Actually Cheaper?

Thu, 06 Aug 2026 00:00:00 +0000

What is the actual break-even between bags and bulk?

For the most common US pricing — a 2 cu ft bag at $4.29 and bulk mulch at $38 per yard with a $65 delivery — the crossover is 3.26 cubic yards. Below that, bags cost less in total. Above it, bulk does.

The arithmetic is short enough to do on a phone in the aisle:

Bagged cost per yard = 13.5 × bag price. At $4.29, that is $57.92.
Saving per yard by going bulk = $57.92 − $38.00 = $19.92.
Break-even = delivery fee ÷ saving per yard = $65 ÷ $19.92 = 3.26 yards.

What matters is that none of those three inputs is fixed, and the answer is extremely sensitive to all of them. “Bulk is cheaper past three yards” is a statement about one specific set of prices that nobody checked.

How Many Bags of Mulch Are in a Cubic Yard?

Thu, 06 Aug 2026 00:00:00 +0000

What is the conversion for every bag size?

A cubic yard is 27 cubic feet. Divide 27 by the bag size and you have the count. Here it is for all five sizes sold in US retail, together with how much ground a single bag actually covers.

Bag size	Bags per cubic yard	Covers at 2 in	Covers at 3 in	Covers at 4 in
0.75 cu ft	36	4.5 sq ft	3.0 sq ft	2.25 sq ft
1 cu ft	27	6 sq ft	4 sq ft	3 sq ft
1.5 cu ft	18	9 sq ft	6 sq ft	4.5 sq ft
2 cu ft	13.5	12 sq ft	8 sq ft	6 sq ft
3 cu ft	9	18 sq ft	12 sq ft	9 sq ft

The coverage column is the one that stops overbuying. A 2 cu ft bag covers 8 square feet at the standard 3-inch depth — an area smaller than a bath towel. That is why a modest front bed swallows fifty bags and why people are always surprised by the count. The mulch bags calculator runs your own area against every size at once.

How Much Does a Yard of Mulch Weigh — and Will It Fit in My Truck?

Thu, 06 Aug 2026 00:00:00 +0000

What does a cubic yard of each material weigh?

Volume is identical across materials — a cubic yard is always 27 cubic feet — but weight is not, and the spread is enormous. This table gives the working ranges used by every tool on this site, plus how many yards each class of truck can legally take per trip at the midpoint density.

Material	lb per cubic yard	Half-ton (1,200 lb)	¾-ton (2,000 lb)	1-ton (3,000 lb)
Shredded bark mulch	400–800	2.0 yd	3.3 yd	5.0 yd
Compost	1,000–1,600	0.9 yd	1.5 yd	2.3 yd
Screened topsoil	2,000–2,700	0.5 yd	0.85 yd	1.3 yd
Fill dirt	2,200–2,900	0.47 yd	0.78 yd	1.2 yd
Gravel / crushed stone	2,400–3,000	0.44 yd	0.74 yd	1.1 yd
Sand	2,600–3,000	0.43 yd	0.71 yd	1.1 yd

The pattern is worth stating plainly: mulch is the only material on that list a passenger truck moves in useful quantity. Everything else is a single scoop per trip at best, which is why yards deliver soil and stone by the truckload and why the delivery fee is not the rip-off it looks like.

When to Mulch and How Often to Replace It

Thu, 06 Aug 2026 00:00:00 +0000

When is the right time to mulch?

Late spring, after the soil has warmed. Mulch is an insulator, and insulation works in both directions: laid over cold March soil it keeps that soil cold, delaying the root activity that everything else depends on. Wait until the soil is around 55°F a couple of inches down — in most of the US that lands somewhere between mid-April and late May — and mulch does what you actually want, which is holding warmth and moisture in and keeping weed seeds in the dark.

How to Fill a Raised Bed Without Overpaying for Soil

Thu, 06 Aug 2026 00:00:00 +0000

How much soil does my bed actually need?

Length × width × depth in feet, divided by 27 for cubic yards. Here are the sizes people actually build, with bag counts rounded up.

Bed size	Depth	Cubic feet	Cubic yards	1.5 cu ft bags	2 cu ft bags
2 × 8 ft	6 in	8.0	0.30	6	4
4 × 4 ft	12 in	16.0	0.59	11	8
4 × 8 ft	6 in	16.0	0.59	11	8
3 × 6 ft	12 in	18.0	0.67	12	9
4 × 8 ft	12 in	32.0	1.19	22	16
4 × 8 ft	18 in	48.0	1.78	32	24
4 × 12 ft	12 in	48.0	1.78	32	24
4 × 8 ft	24 in	64.0	2.37	43	32

The depth column carries all the weight here. Doubling a 4 × 8 bed from 12 to 24 inches doubles the fill from 32 to 64 cubic feet and roughly doubles the cost — for a bed that grows almost exactly the same vegetables, since most annual crops work the top 8 to 12 inches. Twelve inches over reasonable native soil is the value sweet spot. Deeper beds earn their keep on top of paving, hardpan or contaminated ground, where the bed is the soil profile. Your own dimensions go into the raised bed soil calculator.

Topsoil vs Garden Soil vs Compost vs Potting Mix

Thu, 06 Aug 2026 00:00:00 +0000

What actually separates these five products?

The proportion of mineral soil to organic matter, and how coarse the whole thing is. Everything else — the name on the bag, the price, the weight — follows from that.

Product	What it is	Typical lb per cubic yard	Belongs in	Max share of a growing mix
Fill dirt	Unscreened subsoil, little organic matter	2,200–2,900	Grade changes, backfill below root zone	0%
Screened topsoil	Native upper-layer soil, sieved	2,000–2,700	Lawn base, bulk of a bed, levelling	50–60%
Garden soil	Topsoil pre-blended with compost	~2,035 (calculated)	In-ground beds and borders	100% as sold
Compost	Decomposed organic matter	1,000–1,600	Amendment, topdressing, mix component	25–30%
Potting mix	Peat or coir, bark, perlite — no soil	Light; sold in dry quarts	Containers and seed starting only	Containers only

The garden soil figure is worth explaining, because nobody publishes it. It is a blend, so its weight is a blend too: 70 percent topsoil at a midpoint 2,350 lb per yard plus 30 percent compost at a midpoint 1,300 gives 2,035 lb per cubic yard. That is meaningfully lighter than straight topsoil and it is why a yard of garden soil is a slightly less alarming thing to put in a pickup. All the underlying ranges are in the density and truck-load guide.

How Much Gravel for a Driveway or Patio (Depth & Base Layers)

Thu, 06 Aug 2026 00:00:00 +0000

How deep does gravel go for each job?

Depth is set by load, not by looks. Here is the whole range in one place.

Application	Total depth	Build-up
Decorative gravel in beds	2–3 in	Single layer over woven fabric
Garden path, foot traffic	3 in	2 in of 3/4 in stone + 1 in of fines or pea gravel
Paver or flagstone patio	5–7 in	4–6 in compacted crushed base + 1 in bedding sand
Shed or hot tub pad	4–6 in	Compacted crushed stone, screeded level
Driveway, firm subgrade	4–6 in	Base course + finer top course
Driveway, clay or soft subgrade	8–12 in	Three layers, coarse to fine
French drain	6–12 in	Washed stone around perforated pipe
Dry well / soakaway	as designed	Washed stone, no fines

Two rules run through that table. Coarse stone goes at the bottom, fine stone on top — the large angular pieces bridge the soft subgrade and the fines lock the surface together. And washed stone is used wherever water has to move through, because the fines that make a driveway hard are exactly what clogs a drain.