Measure the length of the eave, or the bottom edge that hangs out over the home, for each section of the roof. Do not add these up; keep the numbers separate.
Multiply the number of rows on each section by the length of the eave of that section. This gives you the total length of battens needed for each section. For example, if you are adding battens to two sides of a roof, each with an eave length of 20 feet, and you will have 15 rows of tiles, multiply 15 by 20 to get 300 feet.
Add together the length of the battens needed in each section to get the total length of batten material needed for the whole roof. Using the example from Step 2, add 300 and 300 to get 600 feet total.
Convert the measurement to meters, if it is currently in feet, by multiplying the number you got in Step 3 by 0.3048. A total of 600 feet of batten material would equal 182.88 meters of batten material.