CFM Chart

 CFM

 Round

 Rectangular Duct

 Supply Register

 Return Grille

60 5 2 1/4 x 10 4 x 10
100 6 2 1/4 x 12 4 x 12 6 x 10
150 7 3 1/4 x 14 4 x 14 6 x 12
200 8 4 x 14 6 x 14 6 x 14
300 9 8 x 8 8 x 14 8 x 14
400 10 8 x 10 8 x 18
500 12 8 x 12 8 x 24
600 12 8 x 14 12 x 18
700 14 8 x 16 14 x 18
800 14 8 x 18 10 x 30
900 14 8 x 20 14 x 24
1000 16 8 x 22 12 x 30
1200 16 8 x 24 18 x 24
1400 16 8 x 28 18 x 30
1600 18 8 x 32 20 x 30
1800 20 10 x 28 24 x 30
2000 20 10 x 30 24 x 30

Note:  Check the manuufacturers spec's on the specific grilles you are using. They may vary from these numbers as manufacturers free area on grilles and registers change. Use this as a rough guide only.

Disclaimer: The information found on this website is for informational purposes only. Any and all preventive maintenance, service, installations should be reviewed on a per job situation. Any work permormed on your heating system should be performed by qualified and experienced personnel only. Comfort-Calc or it's personnel accepts no responsibility for improper information, application, damage to property or bodily injury from applied information found on this website.