Pipe Sizing Calculator
D = sqrt(4Q / πv). Calculate the minimum pipe inner diameter required for a given flow rate and maximum velocity. Recommends the next standard NPS size.
Min. Diameter
--
inches
Recommended NPS
--
inches (Sch 40 ID)
Actual Velocity
--
ft/s
Pipe Area
--
in²
Standard NPS Comparison
| NPS | Sch 40 ID (in) | Velocity (ft/s) | Status |
|---|
How this was calculated
D = sqrt(4Q / πv)
Q is converted from gpm to ft³/s (1 gpm = 0.002228 ft³/s).
The minimum diameter ensures actual velocity does not exceed the specified maximum.
Standard NPS sizes (Schedule 40) are checked to find the smallest size that meets the requirement.
Need help with piping design, facilities engineering, or flowline sizing?
Book a free strategy call →Understanding Pipe Sizing
Proper pipe sizing balances capital cost (smaller pipes) against operating cost (pressure drop and pumping power increase with velocity). Industry guidelines typically recommend 3-10 ft/s for liquids and 30-100 ft/s for gases.
In oilfield applications, pipe sizing is critical for flowlines, gathering systems, water injection lines, and facility piping. API RP 14E provides erosional velocity limits for production piping.
All calculations run in your browser. Built by Groundwork Analytics.