The size of this piece depends on the size of your hook and the weight of your thread.

Centerpiece
Size 80 thread uses 3 balls (no yardage or weight given for balls) and the projected size of the Centerpiece is 21.25 in / 540 mm (side to side) and 23.62 in / 600 mm (top to bottom).

Size 30 thread uses 4.2 balls of thread (500 yards per ball).
Projected size of the Centerpiece is 33 in / 83.8 cm (side to side) by 37 in / 94 cm (top to bottom).

Place mats
The pattern calls for 6 place mats - 1 for each side of the Centerpiece.

#80 weight thread uses 1 ball of thread (no yardage or weight of the ball given) per place mat. Each place mat would be about 15 in / 380 mm (wide). No height given.

Gauge
The gauge for #30 weight thread is 6 blocks x 6 rows = 1 inch square (pre-block).

Hook Size
Use the smallest hook that you are comfortable with when using your chosen thread.

Thread Weight
The larger weight thread that you choose will make a larger item. The original pattern was intended for #80 - #100 weight thread.