1. Flow Charts for Pipes
Water flow charts:
This water flow rate table is showing rate of water through copper tubing - pipes.
Volume of flow is at one foot per minute velocity.
Type L Copper Tube
Dia. inches: Cubic ft/min: Gallons/minute:
1/8" 0.0002 0.002
1/4" 0.0005 0.004
3/8" 0.0010 0.008
1/2" 0.0016 0.012
3/4" 0.0034 0.025
1" 0.0057 0.043
1 1/4" 0.0087 0.065
1 1/2" 0.0124 0.093
2" 0.0209 0.161
Type K Copper Tube
Dia. inches: Cubic ft/min: Gallons/minute:
1/8" 0.0002 0.0014
1/4" 0.0005 0.0039
3/8" 0.0009 0.0066
1/2" 0.0015 0.0113
3/4" 0.0030 0.0267
1" 0.0054 0.0404
1 1/4" 0.0085 0.0632
1 1/2" 0.0196 0.0895
2" 0.0209 0.1565
This water flow rate table shows water flow through pipes .
Volume of flow is at one foot per minute velocity in these pipes.

2. Schedule 40 pipe
Dia.
inches:
Cubic ft/min: Gallons/minute:
1/8" 0.0004 0.003
1/4" 0.0007 0.005
3/8" 0.0013 0.010
1/2" 0.0021 0.016
3/4" 0.0037 0.028
1" 0.0062 0.046
1 1/4" 0.0104 0.078
1 1/2" 0.0141 0.106
2" 0.0233 0.174
Schedule 80 pipe
Dia. inches: Cubic ft/min: Gallons/minute:
1/8" 0.0003 0.002
1/4" 0.0005 0.004
3/8" 0.0010 0.007
1/2" 0.0016 0.012
3/4" 0.0030 0.025
1" 0.0050 0.037
1 1/4" 0.0088 0.067
1 1/2" 0.0123 0.092
2" 0.0206 0.154
please do not rely on these figures as being totally accurate, the above is provided to give a general idea of flow
rates
Frequently Asked Questions
Q. "How do I determine what type of tubing I have?"
A. In copper pipe, Type L (which in most cases is stamped or printed with blue writing) and
Type K (which in most cases is stamped or printed with green writing) are typically used for
residential plumbing and is sold in nominal sizes which are approximately an 1/8 inch less than
the actual outside diameter. Type K has the heaviest wall thickness, and is typically used for
burial underground. Type L is more of a multi-purpose tubing, and is used for most other
installations. Type M, which in most cases is stamped or printed with red writing, has the lightest
walls (meaning it has the largest inner diameter of the three types listed) and is typically used for
drainage and other low-pressure applications. Please keep in mind that wall thickness will vary
with nominal sizes, and the resulting inside diameter is always within a few hundredths of an
inch of the nominal size. In PVC pipe, Schedule 80 has thicker walls than the standard Schedule

3. 40, and as a result, a smaller inner diameter. However, this is only true of Schedule 80 pipe; the
fittings are different in that the outside diameter of the fitting gets larger, so it can accomodate
the pipe. In older designation systems, Schedule 40 was designated as Standard Wall pipe, and
Schedule 80 was designated as Extra Strong walled pipe. Schedule 40 is the most widely used
form of PVC pipe.

4. Water
Flow
Through
Pipes
A rough rule of thumb, based on engineering experience, for use with water in
metallic pipes which are 3-in diameter and greater and are in continuous service is
that the velocity in feet per second (fps) should not exceed about 4 plus one-half of
the nominal diameter in inches, i.e., 4 + d/2. Thus, the velocity in a 3-in pipe should
normally be kept below 5.5 fps, and the velocity in a 16-in line could be as great
as 12 fps, in the absence of other constraints. In no case should a pumped liquid velocity be
allowed to exceed 14 to 17 fps. Below 3-in diameter, velocities of 5 fps are acceptable for liquids.
Table 1: Economical Pipe Sizes for Carbon Steel Schedule 40 Pipe
Flow Rate, gpm Nominal Pipe Size, inches
64 to 130 3
130 to 280 4
280 to 660 6
660 to 1,150 8
1,150 to 2,200 10
2,200 to 3,200 12
3,200 to 4,250 14
4,250 to 5,700 16
Source of Table 1: Sandler, Henry J. and Edward T. Luckiewicz. Practical Process Engineering. New York: McGraw-Hill, 1987.
A simple equation for calculating the velocity of water in a pipe is shown in Equation 1.
Equation 1: Velocity of Water in a Pipe
Where d = diameter in inches
The exact formula for calculating the flow of water in a pipe is given in Equation 2.

5. Equation 2: Volume Flow Rate