Calculation help please.

[ChrisNJ]

Long time no see guys, tried the sticky calculators but could not get it to work, what do you think the volume of these would be cord wise ?

The oak logs are approx. 20-28 inch in diameter and approx. ten feet long (9 of them)

Now I would average 24 inches by 10 ft x 9 = 180sq ft ? = 1.4 cords ? How does that look.

 

[byQ]

Long time no see guys, tried the sticky calculators but could not get it to work, what do you think the volume of these would be cord wise ?

The oak logs are approx. 20-28 inch in diameter and approx. ten feet long (9 of them)

Now I would average 24 inches by 10 ft x 9 = 180sq ft ? = 1.4 cords ? How does that look.

Let's lay those logs out. We know a cord is 4' x 4' x 8'. If you grab two of those logs and lay them side by side you are now at a 4' width. And if we take 2 more logs and lay them on top of the other two we are at 4' high (two of the dimensions of a cord).

So we've now used 4 logs and we've got a width of 4', a height of 4', and a length of 10'. A cord is 4'x4'x8' = 128ft3, 4'x4'x10' = 160ft3 and you still have 5 logs left. So let's double those 4 logs, 160 (x2) = 320 ft3 (that is 8 logs). Now you have one log left. So 320/8 = 40ft3 (volume of one 10ft log). So 320ft3 + 40ft3 = 360ft3.

360/128 = just a little less than 3 cords. Cut firewood may contain more air space than logs, so maybe 9 logs is a bit over 3 cords.

 

[Wood Duck]

I'd do the calcs like this: radius of a log = 12 inches = 1 ft. The area of the end of a log is Pi r^2 = 3.14 x 1^2 = 3.14 square feet. Volume of a log is 10 ft x 3.14 sq ft = 31.4 cubic feet. 31.4 cubic feet per log x 9 logs = 282 cubic feet of solid wood. A cord is about 85 cubic feet of solid wood, so you have 282 cubic feet / 85 cubic feet/cord = 3.3 cords.

Remember a cord is 128 cubic feet of stacked wood and the air between them. It is only about 85 cubic feet of solid wood.

 

[ChrisNJ]

Geez I was way off, thanks a lot.

 

[smokedragon]

+1 to wood duck.

OP, you have a lot of wood on your hands there.

 

[jaychino415]

+1 to Wood Duck

Good amount of Oak you got there. Get them c/s/s if you haven't done so already.

 

[paul bunion]

Let's lay those logs out. We know a cord is 4' x 4' x 8'. If you grab two of those logs and lay them side by side you are now at a 4' width. And if we take 2 more logs and lay them on top of the other two we are at 4' high (two of the dimensions of a cord).

So we've now used 4 logs and we've got a width of 4', a height of 4', and a length of 10'. A cord is 4'x4'x8' = 128ft3, 4'x4'x10' = 160ft3 and you still have 5 logs left. So let's double those 4 logs, 160 (x2) = 320 ft3 (that is 8 logs). Now you have one log left. So 320/8 = 40ft3 (volume of one 10ft log). So 320ft3 + 40ft3 = 360ft3.

360/128 = just a little less than 3 cords. Cut firewood may contain more air space than logs, so maybe 9 logs is a bit over 3 cords.

I like this method, it gets you a quick estimate that you can do in your head. I look at a 24" log and say at 8' it is 1/4 cord or I need 32 running feet to get a cord. For three cords I need 96 running feet. OP has 90 running feet so he has just under 3 cords. Wood duck's figure that a cord of wood contains only 85 cu feet of solid wood can't be correct in my opinion. As 85/128= .664. I don't think that anybody here is going to tell you that a 'cord' of wood neatly stacked is 2/3 wood and 1/3 air. Mine certainly don't look like that to me and I don't think I could stack that much air into one if I tried without criss/cross stacking.

This method figures automatically that you have about 100 of solid wood/cord or the air within a stack is 21.5%. It is the difference in area between a square and a circle drawn within it.