Plumbing & HVAC calculators
Size ducts from CFM, select drain pipe diameters, find air filter dimensions, and calculate pipe thread specs, all in inches.
Popular plumbing & HVAC tools
Critical sizing calculators for mechanical systems.
HVAC Duct Size Calculator
Size round and rectangular ducts from CFM airflow in inches.
Air Filter Size Calculator
Find your AC filter dimensions in inches from nominal size.
CFM to Duct Diameter
Convert CFM to round duct diameter using velocity method.
Pipe Thread Size Guide
NPT and BSP thread dimensions and ID/OD charts in inches.
HVAC & air systems
Plumbing & water
Drain Pipe Size Calculator
Select drain pipe diameter from fixture units
Pipe Thread Size Guide
Identify pipe thread sizes: NPT, BSP, and dimensions
Water Heater Capacity Calculator
Calculate water heater size from household needs
Shower Flow Rate Calculator
Calculate shower head flow rate and coverage in inches
Quick reference: common pipe & duct sizes
Common HVAC round duct sizes
| Diameter | Max CFM |
|---|---|
| 4 inch | 50 CFM |
| 6 inch | 100 CFM |
| 8 inch | 175 CFM |
| 10 inch | 260 CFM |
| 12 inch | 370 CFM |
NPT pipe thread sizes (OD in inches)
| Nominal | OD |
|---|---|
| 1/4 inch | 0.540" |
| 1/2 inch | 0.840" |
| 3/4 inch | 1.050" |
| 1 inch | 1.315" |
| 1-1/2 inch | 1.900" |
Explore more categories
Construction for building systems, volume for tank and flow calculations.