How do you figure the number of clips needed iN A 12X12 CEILING TILE INSTALLATION

You can go to the armstrong website thre is a calculation tool you can use Roughly you will need 156 clips need 48 for tiles on each end wall and then 24 for each side wall. Then one clip per tile for rest of tiles

Say your room is 12 x 13 If you start on the 12 ft wall then you need 4 clips per tile along that wall . Two will go between the tile and wall and then two will go between the tile and next tile. You will then need two clips for each tile going along both 13 ft sides .That would call for 26 per wall and then 48 along the one 12 ft wall and another 48 along the last 12 foot wall . Add or subtract clips per room size All other tiles take one clip take how many tiles you need minus the borders and that will be how many tiles and clips you need . A 12 x 13 is 156 sq ft. 156 minus 50 would be 106 tiles so you need 106 more clips Hope this helps