How do i work out how much carpet I need for my stairs? 12 stairs, W33" D9" H7". Thanks.?

Answer 1

You will use width 4'
Length about 20'

This is done by stripping a 12' width of carpet into 3 widths.
20' divided by 3 = 6'8"
So you have 3 pieces 4' X 6'8".
The critical part is not to have a seam anywhere except at a valley of the step. The carpet must run lengthwise down the steps, not across, to prevent "grinning". The direction of the pile runs lengthwise.

Your numbers of 9" and 7" = 16" per step. That's not enough. I figured 20", 1'8" per step. X 12 steps =20'.

So adding each step to determine where a seam will fall,
1'8"+1'8"+1'8"+1'8"=6'8". This works as a total for 4 steps, and uses 1 strip of the carpet 6'8 in length. The other two strips complete the job since 3 lengths @ 6'8" =20'.
Seams will fall in a valley of the step.

Carpet need = 12' X 6'8". 12 X 6'9" = 9 sq yards. 81 sq ft.

I don't know if you considered the Riser at the top of the stairs, to be covered with the stair carpet, or if you are leaving the original drop down carpet from an upstairs hall.
You could be safe and buy a 12' X 7' = 9 1/3 sq. yds=84 sq. ft.
12' X 7' gives you 21 ' of length, enough to cover the top riser.

I'm posting this much info so that you understand why carpet is never run across the steps. It must be stripped as above.

Answer 2

D9+H7 x amount of stairs x W33

Answer 3

length(or depth) in inches times width in inches= square inches needed for 1 stair. divide by 12 to get square feet for one stair. Then multiply by 12 to get square feet for all 12 steps.

you have too many variables in your question, assuming your steps are rectangle shaped.

Answer 4

7+9=16
times 12
so you need
33" by 192"

Answer 5

allowing for turn ups get 18 feet

Answer 6

just take what measurements you have and take them along to where you will buy your new carpet and they will work it all out for you! easy...

Answer 7

every two steps one meter square