View Full Version : What's the formula for figuring base stone??

4 seasons lawn&land
06-03-2009, 08:51 PM
I forgot how to figure it out. I need to do a 7" base, 300 sq. ft.

06-03-2009, 09:36 PM
300 sf divided by 46 (7 inches) gives you 6.5 yards. If you need to know how many tons that is multiply 6.5 by 1.33, which gives you 8.6 tons. Don't forget to allow for compaction. I'd add another 10 to 15% to either or. I'd get 7 to 7.5 yards, or 9.5 to 10 tons. Hope this helps.

DVS Hardscaper
06-03-2009, 10:51 PM
300 x 7

{Next you have to convert the inches (the 7)}

- so you divide by 12

- next divide by 27 to convert to cubic yards

- next multiply by 1.2 to convert yards to tons

- next multiply by 1.5 to compensate for compaction

it will look like this:

300 x 7 / 12 / 27 x 1.2 x 1.5 = 11.67 tons

This is how my super dooper looper estimating system figures each and every single job and we have done it this way for 13 years :)

yes, from time to time we do usually have a little left over gravel. But we have a giant truck that can take it away to our world head quarters where we have a yard to store materials.

About 2 years ago 2 people at this board told me my formula was no good!! Well, I won't mention SeaGees name, but one of those people ran his business into the ground and the creditors came in and changed the locks. And the other person that mentioned my formula is off is a good guy, but hasn't been a contractor for many years!

It works for me. If you wanna be like me (a cool mother-you-know-whater) then feel free to jump on the band wagon use my formula.


4 seasons lawn&land
06-04-2009, 08:03 PM
haha, thank's.

06-05-2009, 12:20 AM
base here is 1.5 tons a yard

06-05-2009, 12:32 PM
finding yards...

sq feet / 12 = Y

Y x's inches of base = Q

Q x 1.25 compaction = W

W / 27 = cubic yards of base aggregate.

06-10-2009, 06:13 AM
Here's an idiot-proof asphalter solution, take your square footage (300 sq ft) divide by 81 equals 3.7 tons per 2 inches of material. So if you have 7 inches, take 3.7 times 3 (to get 6 inches) equals 11.1, then divide 3.7 in half ( for the 1 inch to make 7)1.85 ton then you get 12.95 tons total compacted. Or find an on-line calculator like I do and it told me 300 sq.ft. is 12.667 tons @ 7 inches.

06-10-2009, 12:18 PM
sq/ft devided by 175 x inches of base x 1.1 = tons of compacted base

13.2 tons

06-10-2009, 08:50 PM
I use in-place weight per cubic foot rather than expansion or compaction ratios.

(((300 / 12) * 7) * 150) / 2000 = 13.125 tons

I would round up. 14 tons. Gravel is cheap, time and delivery isn't. I'd rather look at it than look for it. Take away the left-over and use it on your small jobs where delivery isn't economical.

formula is: square feet of base / by 12 inches * desired inches * in-place compacted weight per cubic foot = total weight... divide by 2000 and round up for tons to order

Now, with that out of the way. Why 7" base? Who does odd numbers? Also, do you have 300 finished square feet of pavement? Don't forget you need at least 7" of base extension beyond your pavement edge on all sides... so you'll need to add that square footage to your formula.

So if your pavement is say 30' x 10', you'd have to add more than 50 square feet to your calculation... another 2.2 tons... forget to add that and you're eating some material cost (or doing your base wrong).

06-11-2009, 03:21 PM
Here's my formula I try to keep things as simple as possible
Area x depth / 240 gives the yards I need
If I want to convert it to tons I just multiply the results by 1.33

300 x 7 / 240 = 8.75 yds x 1.33 = 11.63 tons pretty close to the super dooper looper but less math. :)
One last note if you buy it around this time of the season in tons account for moisture content so multiple by 1.5

06-12-2009, 12:02 AM

get .5833 by dividing 7 by 12.

/27 is cubic yds.

*2 accounts for conversion to tons AND compaction