Greenhouse Base Calculator
Get the gravel base right before your greenhouse kit shows up. Enter your greenhouse footprint and base depth, and this calculator gives you cubic yards, tons, bag counts, and delivered cost.
Measure straight across the widest point.
A 4 in gravel base is typical for kit greenhouses
Covers spillage and compaction. 5–10% is normal.
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Bags or bulk delivery?
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Coverage & weight
Material profile
A gravel base is calculated by volume, not just area. Multiply the greenhouse footprint (length times width) by the base depth in feet, add a waste percentage for compaction and spillage, and convert the result to cubic yards. Multiply cubic yards by the material’s weight per yard (about 2,800 lb for crushed run) to get tons, then round up to a full order since suppliers sell in fractions of a ton or by the bag.
Base Material Comparison
Crushed run and pea gravel behave differently once they’re down. Pick based on whether you want a compacted, stable base or a permeable, finished floor.
| Material | Weight per Cu Yd | Drainage |
|---|---|---|
| Crushed run / road base | 2,800 lb | Poor once compacted (by design, for a stable base) |
| Pea gravel | 2,600 lb | Good, some fines |
Greenhouse base material weight by type
| Type | Weight per yd³ | Best for | Drainage |
|---|---|---|---|
| Crushed run / road base | 2,800 lb | Compactable level base for framed kits | Poor once compacted (by design) |
| Pea gravel | 2,600 lb | Good drainage, permeable floor option | Good, some fines |
Figures are for dry material. Wet or freshly delivered material can weigh noticeably more.
How to calculate base gravel you need
- Measure your greenhouse footprint, length by width in feet.
- Choose your base depth, typically 4 in for a compacted crushed run base under a framed kit.
- Convert the volume to cubic yards and add a waste percentage for compaction and spillage.
- Multiply cubic yards by your material’s weight per yard to get tons.
- Round up to the tonnage your supplier sells, or convert to bags if you’re buying bagged material.
Worked example
For a 10 x 8 ft greenhouse footprint, 4 in of crushed run, and 10% waste:
- Footprint10 x 8 ft
- Depth4 in
- Area80 sq ft
- Waste factor10%
- Volume needed29.3 cu ft (1.09 cu yd)
- MaterialCrushed run / road base (2,800 lb/cu yd)
- Tons to order1.75 tons
- Delivered cost$169.00
Recommended depth by project
| Project | Recommended depth | Notes |
|---|---|---|
| Framed greenhouse kit base | 4-6 in | Compactable base like crushed run under a level sill or frame |
| Gravel floor / walking surface | 2-4 in | Pea gravel or similar for a permeable, finished floor |
| Raised bed or planting area base | 2-3 in | Thin drainage layer under soil, not a structural base |
| Cold-climate frost protection | 6-8 in | Deeper compacted base helps resist frost heave under a permanent foundation |
Bags or bulk delivery?
An 80 sq ft greenhouse base sits right at the edge of what’s practical in bags. This example needs about 1.75 tons delivered in bulk, or roughly 59 bags of bagged gravel. Bulk usually wins on cost per ton, but a small footprint like this can still make sense in bags if you don’t have truck access or a place for a bulk drop.
- Go bulk if you can get truck accessdelivery minimums are usually built around 1+ ton loads, and cost per ton drops fast past that.
- Go bags for tight accessno driveway clearance for a dump truck, or a base behind a fence or gate, favors 40-50 lb bags.
- Check the delivery fee separatelybulk pricing often includes a flat delivery charge on top of the per-ton material cost.
- Round up your tonnage ordersuppliers sell by the half or quarter ton, so your order total will be rounded above the raw calculated tonnage.
Common mistakes
- Skipping compactionan uncompacted base settles unevenly and can throw a framed greenhouse kit out of square.
- Using the wrong depth for the climatecold climates with real frost heave need a deeper, more stable base than the standard 4 in.
- Not accounting for delivery minimumsa small footprint like 80 sq ft may fall under a supplier’s bulk delivery minimum, making bagged material the more practical choice.
- Skipping landscape fabricwithout it, weeds grow through the base and crushed run gradually works its way into the native soil.
What this calculator assumes
Adjust your result if your project differs from these.
- Footprint is entered as a rectangular length by width
- Depth is uniform across the entire base, no sloped grading
- Waste percentage covers compaction settling and spillage during placement
- Tonnage is based on the standard weight per cubic yard for the material chosen
- Does not include a poured concrete footing or perimeter foundation, only the loose base material
Common questions
How deep should a greenhouse gravel base be?
4-6 in of compacted crushed run is standard for a framed kit. Cold climates with frost heave concerns may need 6-8 in.
Crushed run or pea gravel, which is better for a greenhouse floor?
Crushed run compacts into a stable, level base and is the standard choice under framed kits. Pea gravel drains well and works as a finished, permeable floor but doesn’t compact as firmly.
Do I need to compact the base before setting up the greenhouse?
Yes. Compact in shallow lifts with a plate compactor. An uncompacted base settles unevenly and can throw the kit’s frame out of square.
Can I skip the gravel base and set the greenhouse on soil?
You can, but soil shifts with moisture and won’t stay level, which stresses a framed kit’s joints and glazing over time.
Is it cheaper to buy gravel in bulk or bags for a small greenhouse base?
Bulk usually costs less per ton but comes with a delivery fee and truck access requirements. For a small footprint with tight access, bagged material can be more practical even at a higher per-ton price.
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Greenhouse Base Calculator Estimate
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materialcalculate.com/tools/greenhouse-base-calculator/
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.