View Full Version : Boulder formula driving me crazy help?

07-22-2008, 07:05 PM
Hey guys, ive just recently been given the chance to install boulders as a border around several beds at 2 of the properties that i service. one is commercial, the other residential. i actually sold them on boulders, rather than retaining block, blk diam, or anything else because we agreed it looked best. My problem is, these nurserys and rock yards are not even coming close to giving me a way to figure these jobs out. Since im new to boulders, i dont know how many i will need, less ofcourse measuring EVERY single boulder, which im here hoping thats not the only answer. it doesnt have to be a perfect formula, but man i cant even get a guess out of these guys. im looking to use volleyball to basketball size boulders, round and not like colors. now from what i can tell these are what the boulder industy considers 1ft (volleyball) to 2 ft basketball) boulders? Please has anyone had experience with this, and can u help me. say i need 80 linear feet worth of edging = _____2ft boulders. since they only sell by the ton, i cant just add the 2foot boulder X my linear feet right? URGGHH IM LOST

White Gardens
07-22-2008, 07:22 PM
Around here, the local suppliers have a catagory of size. Unfortunatly they aren't all the same.

One range is 1.5 feet to 3 feet. So, I find the average and do my calculations with that. Unfortunatly you don't know how many boulders are in a ton, as each load will be different.

So, if you got more than one job to use boulders on, start with the smallest one so you can get an idea on have many pounds = linear feet. If you have any left over, no sweat, you'll just use the excess for the next job, and you'll have a better idea of how much to get.

It's ok to have some left over in the end, just call it inventory and try to sell them on another job, or just stick a few in your own yard.

Another thing I've done in the past is on a few small jobs, I'll actually go hand-pick each boulder to make sure I have some uniformity and not have a bunch of small rocks left over.

Good luck.

07-22-2008, 07:56 PM
Armour stone is 165 or 185 lbs per cubic ft. One or the other, I don't know if this would apply. But it works for cubical stone anyways.

Kate Butler
07-23-2008, 07:40 AM
Granite is 167 lbs./cu.ft. Here is a link to a calculator for the volume of spheres. Once you know the volume, you can figure the weight easily.


It would be useful to know what the composition of these boulders is. BTW, where I live, something that size would be called round rocks - boulders are bigger than 3'-4' diameters.

07-23-2008, 08:45 AM
you need to go to your rock yard and become familiar with their standardized sizes, take your measurements with you. it is part guess work, if we are talking about huge boulders custom select them to meet your measurement needs. read kate butlers post again

07-24-2008, 09:18 PM
What are you having to pay for those granite boulders in your area? per ton?

07-25-2008, 07:39 AM
1-2 footers are 140.00.

07-25-2008, 09:48 AM
140 per ton or a piece?

07-25-2008, 03:59 PM
140 per ton of "1 to 2 footers" as they call them. when i asked him about how many boulders i would get within that ton, he explained he didnt have any idea...from 20 to 40. so, as you can see, its looking like im just going to have to order a few tons and sell any leftovers into another landscaping job. i will also note the amount from each ton, and keep using the same distributer so that in the future, i can have a better idea of the volume and length, verse weight.

07-25-2008, 06:33 PM
Can you go to his yard, and see what a ton will get you?

07-25-2008, 07:38 PM
yeah i actually went to this place the other day right. they were advertising $64 per ton of 1-2 footers. So compared to the other nurserys, this place was less than half the price. i show up and its they are decent rock, only thing is they appear to be chipped right off the moutain(distorterd colors, scratched, dusty, etc). So they had a few tons already wired up on pallets and i was able to get a visual and kind of calculate approimately how many tons i would need. However, im still not entirely sure i want to buy these boulders considering my customers my have issues with the cosmetic appearance, although its not all that bad. Just compared to those nice polished 1-2 footers that nurseys sell for $140, these look like POS.

07-25-2008, 08:20 PM
What is the most popular size of stones used in landscaping up north? 1-2'? What about the smaller stuff like 6"? I know a farm that there are several piles of nice stone but am wondering if it is worth hauling it out to sell.

07-26-2008, 12:05 AM
not to much of the 4-6 stuff around the burbs of MI. It seems like the boulders are really taking off around here. For example, i just saw an add on craigslist where a guy was giving away an entire front yard of slate stone, in very decent condition. When we talked, he explained that he wanted 1-2 ft boulders instead and just wanted the slate gone. I think they look the best also, especially the boulder landscape designs that incorporate 2 tiers. The bigger homes in MI, like 2500 sq ft + are using im guessing 4-6 ft boulders and they look really good.