Drain Slope Calculator (1/4 per Foot)
What is the minimum slope for a drain pipe?
The IPC minimum is 1/4 inch per foot (2%) for pipe 2-1/2 inches and smaller. For 3-inch through 6-inch pipe the IPC allows 1/8 inch per foot (1%), and 1/16 inch per foot for 8-inch and larger, provided the design velocity stays at least 2 ft/s. The UPC is generally stricter, so check your adopted code and AHJ.
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Use the Drain Slope Calculator (1/4 per Foot) to get an exact answer for your inputs.
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