In general measure the longest room length by the longest room width Figure 1, Length 1x Length 2 = Area 1

In awkward shaped rooms, to be precise make a series of squares/rectangles within the room, calculate the area of each and add together, Figure 2.

In Fig 2 six different measurements need to be taken, multiplied together ie:
Length 1x Length 2 = Area 1
Length 3x Length 4 = Area 2
Length 5x Length 6 = Area 3

Then add Area 1+ Area 2+ Area 3 = Total Area Required.

Add 5% for cutting allowance.

Each product comes in a pack, each pack covers a defined number of sq meters. Part packs are not sold. Pack size varies depending on the product.

To calculate the number of packs you require, you divide the Total Area Required in sq meters by the pack size in sq meters and then round the answer up to the nearest full pack.

Handy Conversions

Square footage divided by 9 = square yardage
Square meters multiplied by 1.196 = square yardage
1 square foot = 144 sq inches = 0.0929sq meters
1 square yard = 9 square feet = 0.8361 square meters

When measuring for carpet and vinyl, they normally come in 4 meter wide rolls, one side of measurement will have to be 4meters/15ft eg if a room is 3m x 5m you will need 4m x 5m to cover the room.