Boulder Weight Calculator
Enter a boulder’s length, width, and height along with its rock type to estimate its weight in pounds and tons — useful for planning equipment, trucking, and cost.
A small buffer for breakage and estimate error. 5–10% is normal.
Everything is calculated in your browser. Nothing you type is sent anywhere or stored.
Equipment needed
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Weight & density
Rock profile
A boulder roughly 3 ft × 2 ft × 2 ft has an estimated volume of 8.4 cubic feet (length × width × height × 0.7, the standard adjustment for irregular natural stone). In granite (165 lb per cubic ft), that boulder weighs about 1,386 lb — just under 0.7 tons. Weight varies significantly by rock type, so always confirm density with your supplier before ordering equipment or a delivery vehicle.
Typical boulder weights by size
Volume is estimated as size × size × size × 0.7, the standard rule of thumb for roughly round natural boulders.
| Boulder size | Est. volume | Granite (165 lb/cf) | Limestone (155 lb/cf) |
|---|---|---|---|
| 1 ft | 0.7 cu ft | 115.5 lb | 108.5 lb |
| 2 ft | 5.6 cu ft | 924 lb | 868 lb |
| 3 ft | 18.9 cu ft | 3,118.5 lb (1.6 tons) | 2,929.5 lb (1.5 tons) |
| 4 ft | 44.8 cu ft | 7,392 lb (3.7 tons) | 6,944 lb (3.5 tons) |
| 5 ft | 87.5 cu ft | 14,437.5 lb (7.2 tons) | 13,562.5 lb (6.8 tons) |
| 6 ft | 151.2 cu ft | 24,948 lb (12.5 tons) | 23,436 lb (11.7 tons) |
How to calculate boulder weight
- Measure the boulder's three longest dimensions. Length, width, and height in feet, taken at the widest points along each axis.
- Multiply the three dimensions together. This gives the volume of the boulder’s bounding box, as if it were a rectangular block.
- Apply the 0.7 shape factor. Multiply by 0.7 to account for the irregular, rounded shape of natural stone versus a solid rectangular block.
- Multiply by the rock's density. Different stone types weigh different amounts per cubic foot — granite is denser than sandstone, for example.
- Multiply by quantity if ordering multiple boulders. Repeat for each boulder, or multiply total weight by boulder count for a matched order.
Worked example
Using the calculator’s defaults: a 3 ft × 2 ft × 2 ft boulder, granite, 1 boulder, 5% ordering buffer, $150 per ton, $85 per boulder.
- Dimensions3 ft × 2 ft × 2 ft
- Estimated volume (3 × 2 × 2 × 0.7)8.4 cu ft
- Rock typeGranite (165 lb/cu ft)
- Estimated weight (8.4 × 165)1,386 lb
- Quantity1 boulder → 1,386 lb total
- With 5% ordering buffer (1,386 × 1.05)1,455.3 lb (0.73 tons)
- Estimated cost (0.73 tons × $150/ton)$109.15
Equipment needed by weight
Match your handling equipment to the boulder’s estimated weight before it arrives on site.
- Under 50 lbHand-placed by one or two people; no equipment needed.
- 50–300 lbHand truck, dolly, or pry bar with two to three people, or a small engine hoist.
- 300–1,000 lbSkid steer with pallet forks or a mini excavator with a thumb attachment.
- 1,000–3,000 lb (0.5–1.5 tons)Compact excavator or skid steer with a boulder grapple attachment; standard for most accent boulders.
- Over 3,000 lb (1.5+ tons)Full-size excavator with grapple, or crane placement; confirm truck and trailer weight ratings for delivery.
Common mistakes
- Assuming a boulder is a solid rectangular block.Using length × width × height without the 0.7 shape factor overestimates weight by roughly 30%.
- Guessing at rock density.Density varies by stone type and even by quarry — granite (165 lb/cf) and sandstone (145 lb/cf) differ by nearly 14%.
- Underestimating equipment needs.A 3 ft boulder in granite already weighs close to 1,400 lb — well beyond what two people or a hand truck can safely move.
- Forgetting delivery vehicle weight limits.A pickup truck bed is typically rated for 1,000-2,500 lb payload — a single large boulder can exceed that alone.
- Not accounting for irregular shape when placing.A boulder’s widest points, not its footprint, determine clearance needed through gates and around structures.
- Ordering by piece count instead of weight for large orders.Boulder size varies naturally — pricing and trucking by ton is more accurate than assuming uniform boulders per piece.
What this calculator assumes
Adjust your result if your project differs from these.
- Volume uses a 0.7 shape factor to approximate an irregular, rounded boulder versus a solid rectangular block.
- Length, width, and height are the boulder’s three longest dimensions, not average measurements.
- Density figures are typical averages for each rock type — actual density varies by quarry and moisture content.
- Weight does not account for internal voids, fractures, or unusually porous stone.
- The ordering buffer applies to total tonnage, not to the number of individual boulders.
- Boulders are assumed dry; wet or saturated stone can weigh several percent more.
Common questions
How much does a 3 ft boulder weigh?
A 3 ft boulder (measured as roughly 3 ft in each dimension) weighs about 3,118.5 lb in granite or 2,929.5 lb in limestone, using the standard 0.7 shape factor.
Why multiply by 0.7 instead of just length × width × height?
Boulders are irregular and rounded, not solid rectangular blocks. The 0.7 factor is an industry rule of thumb that approximates the actual stone volume.
How much does granite weigh per cubic foot?
About 165 lb per cubic foot, though it can range from roughly 160-175 lb depending on the specific granite.
What's the difference in weight between granite and sandstone?
Granite (165 lb/cf) is about 14% heavier than sandstone (145 lb/cf) at the same size.
Can I move a boulder by hand?
Boulders under about 50 lb can be hand-placed by one or two people. Beyond that, use a dolly, pry bar, or mechanical equipment.
How much does it cost to buy a boulder?
Most suppliers price boulders either per ton (commonly $100-200/ton) or per piece for selected accent boulders ($50-150+ each depending on size).
How many boulders fit on a pickup truck?
Depends on the truck’s payload rating, typically 1,000-2,500 lb. A single 3 ft granite boulder near 1,400-3,100 lb may exceed that alone — check your vehicle’s rating.
Do I need a permit to move large boulders?
Usually not for placement on private property, but oversized loads on public roads may need trucking permits — check with your hauler.
How is boulder density different from gravel or crushed stone density?
Solid boulders are denser per cubic foot than loose gravel or crushed stone, which has air gaps between particles reducing bulk density by roughly 30-40%.
What equipment do I need for a 1-ton boulder?
A skid steer or compact excavator with a grapple or forks attachment. A 1-ton (2,000 lb) boulder is beyond safe manual handling.
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Project
| Dimensions | — |
| Quantity | — |
| Rock type | — |
| Handling allowance | — |
Weight
| Per boulder | — |
| Total | — |
| Total (tons) | — |
| Estimated cost | — |
Notes
Estimate generated by materialcalculate.com. Uses the standard L x W x H x 0.7 rule of thumb for irregular natural stone. Confirm quantities with your supplier before ordering.