Slate Chippings Calculator
Work out how many tons or bags of slate chippings you need for a decorative bed, border, or path. Enter your dimensions below for an instant estimate.
Measure straight across the widest point.
Adjust depth below if needed.
Covers spillage and compaction. 5–10% is normal.
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Bags or bulk delivery?
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Coverage & weight
Material profile
One ton of blue/grey slate chippings covers about 110 sq ft at a 2 inch depth — the standard depth for beds and path toppings. A typical 120 sq ft bed needs about 1.1 tons, or 1.2 tons with 10% waste added for curved edges. For areas under about a quarter cubic yard, bagged chippings are usually more practical than a bulk delivery.
Slate chippings needed for common project sizes
Use these as a starting point, then fine-tune with your exact measurements above.
| Project | Depth | Cubic yards | Tons |
|---|---|---|---|
| Small border strip, 10 × 2 ft | 2 in | 0.12 yd³ | 0.18 tons |
| Flower bed, 12 × 8 ft | 2 in | 0.59 yd³ | 0.86 tons |
| Decorative bed (site default), 15 × 8 ft | 2 in | 0.74 yd³ | 1.07 tons |
| Path topping, 30 × 3 ft | 2 in | 0.56 yd³ | 0.81 tons |
| Large bed, 20 × 15 ft | 2 in | 1.85 yd³ | 2.69 tons |
| Courtyard topping, 40 × 20 ft | 2 in | 4.94 yd³ | 7.16 tons |
Slate chipping colors, density and typical use
| Type | Weight per yd³ | Best for | Drainage |
|---|---|---|---|
| Blue/grey slate, 20mm | 2,900 lb | Decorative beds, mulch alt. | Good |
| Plum slate, 20mm | 2,850 lb | Decorative borders | Good |
| Green slate, 20mm | 2,900 lb | Decorative beds | Good |
Figures are for dry material. Wet or freshly delivered material can weigh noticeably more.
How to calculate slate chippings you need
- Measure your bed or border, in feet, and note the length and width (or diameter for round beds).
- Choose your slate color, blue/grey, plum, or green — density varies slightly between colors.
- Set your depth, 2 inches is standard for decorative beds and path toppings.
- Add a waste allowance, 10% covers curved edges, overlap, and spillage during spreading.
- Review tons and bags, then compare bulk delivery pricing against bagged material for your quantity.
Worked example
Here’s the math for the site default: a 15 ft × 8 ft decorative bed at a 2 inch depth, using blue/grey slate (2,900 lb/yd³), with 10% waste added.
- Area15 ft × 8 ft = 120 sq ft
- Depth in feet2 in ÷ 12 = 0.167 ft
- Volume120 × 0.167 = 20 cu ft
- Cubic yards20 ÷ 27 = 0.74 yd³
- Tons (blue/grey slate, 2,900 lb/yd³)0.74 × 2,900 ÷ 2,000 = 1.07 tons
- Plus 10% waste1.07 × 1.10 = 1.18 tons
- Order amountRound up to 1.25 tons in bulk, or about 44 bags at 0.5 cu ft each
Recommended depth by project
| Project | Recommended depth | Notes |
|---|---|---|
| Weed-suppressing membrane topping | 1.5–2 in | Thin dressing over landscape fabric, minimum for full coverage |
| Standard decorative bed | 2 in | Site default; hides underlying soil or fabric completely |
| Path or walkway topping | 2 in | Matches bed depth; lay over a compacted sub-base |
| Border edging strip | 2–3 in | Slightly deeper looks neater and stays put along edging |
| Heavy foot-traffic path | 3 in | Extra depth resists displacement from regular walking |
| Pond or rockery surround | 3–4 in | Deeper layer needed on slopes to prevent chippings sliding |
Bags or bulk delivery?
A 0.5 cu ft bag at $8 works out to about $16 per cubic foot, while bulk slate at $95/ton (about $5.10 per cubic foot before delivery) is roughly 3 times cheaper. Once a job needs more than about 7 cubic feet — roughly 14 bags, or a quarter cubic yard — bulk delivery is cheaper even after the flat $75 fee, though many suppliers still set a minimum bulk order regardless of the math.
- Small job (under 0.25 yd³):borders, pots, or urns — bags are simplest and avoid supplier delivery minimums.
- Medium job (0.25–1 yd³):standard beds — compare your total bag count against bulk-plus-delivery pricing.
- Large job (1+ yd³):large beds or multiple areas — bulk delivery is almost always cheaper per ton.
Common mistakes
- Skipping landscape fabricslate sinks into bare soil and weeds grow through faster, forcing a earlier refresh.
- Ordering by weight without checking color densityblue/grey and green slate run about 2,900 lb/yd³ while plum runs slightly lighter at 2,850 lb/yd³, which shifts tonnage.
- Laying too shallowunder 1.5 inches doesn’t hide fabric or soil and washes away in heavy rain.
- Ignoring edgingwithout steel or plastic edging, chippings migrate into lawns and mulch beds within a season.
- Mixing colors from different batchesquarries vary batch to batch, so buy all the slate for one bed in a single order.
- Not adding waste on curved bedscurved or irregular borders need extra material for cutting and overlap; use 10% or more, not zero.
What this calculator assumes
Adjust your result if your project differs from these.
- Depth is measured after grading, not the loose-poured height straight from the bag.
- Density figures are for settled slate chippings, not loose bag fill.
- Waste percentage covers irregular edges and spillage; increase it for curved beds.
- Coverage assumes a single decorative layer, not multiple depths mixed together.
- Bag size is assumed at 0.5 cu ft per bag; confirm with your supplier before ordering.
- Pricing is a national average estimate; local supplier pricing varies by region and delivery distance.
Common questions
What is the standard depth for slate chippings?
2 inches is standard for decorative beds and path toppings — enough to fully hide soil or landscape fabric without excess cost.
Do I need landscape fabric under slate chippings?
Yes, in almost all cases. Fabric stops chippings from sinking into soil and cuts down on weed growth; skip it only under permeable paving systems.
How much does a ton of slate chippings cover?
About 110 sq ft at a 2 inch depth, or roughly 150 sq ft at a shallower 1.5 inch depth.
What's the difference between blue, plum, and green slate?
Mainly color and slight density — blue/grey and green slate run about 2,900 lb/yd³, plum runs slightly lighter at 2,850 lb/yd³. All three come in the same 20mm angular flake size.
Will slate chippings blow away in wind?
No — at 20mm size and roughly 2,850–2,900 lb per cubic yard, slate chippings are far too heavy for wind to move once laid at the standard 2 inch depth.
Can I lay slate chippings over grass?
Not directly. Kill or remove the grass first, then lay landscape fabric before adding the chippings, or the grass will grow back through within a season.
How often do slate chippings need topping up?
Typically every 2–4 years for high-traffic areas, or 5+ years for undisturbed decorative beds, depending on foot traffic and raking.
Are slate chippings good for drainage?
Yes — the angular shape and open packing drain well, making slate a reasonable choice for beds around downspouts or on slight slopes.
Bags or bulk delivery for a small garden bed?
For beds under about a quarter cubic yard (roughly 45 bags or less), bags are usually simpler even though bulk delivery is cheaper per ton once you’re ordering a full ton or more.
Can I mix slate chippings with other decorative stone?
You can, but color and size consistency looks best when you stick to one slate color and size per bed; mixing works better as a deliberate border or pattern rather than random blending.
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Project
| Shape | — |
| Dimensions | — |
| Depth | — |
| Area | — |
| Material | — |
| Waste allowance | — |
Volume & weight (incl. waste)
| Cubic yards | — |
| Cubic feet | — |
| Weight | — |
| Tons (rounded up) | — |
Shopping list
| Bulk order | — |
| Bagged alternative (0.5 cu ft) | — |
| Estimated cost | — |
Notes
Estimate generated by materialcalculate.com. Assumes uniform depth and standard dry material densities. Confirm quantities with your supplier before ordering.