Skip to main content

.TT pocketEngineer softDesign

... pocketEngineer software for mobile design

pocketEngineer software  animated gif (free)  email me  buy now   
...Ductulator Plus+
...aDuctulator (And)
...aBattMV (And)
...aKitchenExhaust (And)
...tRod Sizer (free)
...pipe_f.Loss (for PC)
...pocketPipe Sizer
...aPipeSizer (And)
...aPocketGas (And)
...rhoAIR (free)
...aRhoAIR (free) (And)
...aPsychroAC (And)
...myEnglishFAQ (free)
...AirTAB superEZ
...Qcool Check
...txtRW (free) (And)
...aCriticalVel (And)
...aPocketPool (And)
 Ductulator Plus+ v2.12 - HVAC duct sizing


the ultimate mobile duct sizer for pocket PC & desktop PC



To take a glance at all pocketEngineer software and OS requirements, click Overview.

For Android OS, see aDuctulator.



 Ductulator Plus: HVAC Duct Sizer on-the-go  

Ductulator Plus, a duct sizing calculations program for Windows Mobile phone & Windows PC,  is specially designed by a professional engineer to replace the conventional hand-held ductulator. It helps you to do duct sizing in a quick and flexible way according to equal friction, velocity, and duct dimensions methods.

Aim: creating a mobile design environment (
ShowMe!) for the practising HVAC engineers & designers in today's mobile world.

Results: Instant solutions at your fingertips.



- duct sizing (rectangle or round) using equal friction or velocity method
- find duct fictional loss rate (duct sizing by duct dimensions method)

- duct sizer for different duct materials
- duct converter (round, rectangular, oval)
- built-in tools for louvre sizer, duct gauge browser, duct velocity guide, pyschrometric air properties calculator, fan motor kW.

- in SI & IP units


 Built-in Features . . .

Unlike the conventional hand-held ductulator which is pre-calculated for the duct roughness of 0.09mm and limited duct sizes, Ductulator Plus offers you the flexibility in duct sizing for different materials such as concrete duct, flexible duct, etc.


Ductulator Plus is designed to offer you the greatest flexibility in duct sizing:
- options for Equal Friction method or Velocity method for rectangle or round duct sizing.

- find duct frictional loss rate (duct dimensions method). This comes handy when you need to determine the friction loss of an as-built or a given duct size.
- options for Colebrook or Atshul-Tsal equations in solving Friction Factor.
- duct converter for round, rectangular & oval duct


Note: Ductulator+ does not calculate fitting / dynamic loss.


. . . & lots more than just a conventional ductulator  

Ductulator Plus gives you detail results like Flow area, Hydraulic diameter, Reynolds number & Friction factor, Velocity pressure, when you need it.


It has built-in tools like Duct Velocity Guide, Louvre Sizer, Duct Gauge Browser, Psychrometric air properties calculator and Fan Motor kW. Pictures explain everything -  view Ductulator+ explained.



 Duct Sizing Methods  

Ductulator Plus offers 3 commonly used methods of duct sizing:

1) The traditional Equal Friction Method of duct sizing is often preferred as it is easy to use and less time-consuming. This method uses a constant pressure loss per unit of duct length. Generally, 0.8 - 1.0 Pa/m of constant pressure loss per meter run has been widely practised in duct sizing.

Because there are practically unlimited number of duct sizes for a given design air flow, the duct sizing problem is solved by iteration technique. Click "calculation explained" for detail.

2) Velocity method is often used when acoustic requirements or minimum air transport/duct velocity is given. 


3) Duct Dimensions method is generally used to find duct friction loss rate for an existing "as-built" duct. 


The formula used in duct sizing is based on the ASHRAE Fundamentals.





 Units in Ductulator+  


Both SI & IP units are available in Ductulator Plus.


Parameter SI Units  IP Units
 Friction loss ratePa/m in.wc/100 ft 
 Duct roughness mmft 
 Air Volume CMH CFM
 Duct dimension mm in.
 Duct velocity m/s FPM
 Flow areamft
 Hydraulic diameter mm in.
 Velocity pressure Pa in.wg

 Did you know? . . . (1) Equivalent cross-sectional Area!  


If you want the same duct friction loss rate, it is inappropriate to convert duct size based on equal cross-sectional area, be it from round to rectangular or square to rectangular. This is because rectangular duct is less efficient than round duct; rectangular duct is less efficient than square duct. See example below, the flow areas (ie, cross-sectional areas) are diffierent for the same duct frictional loss rate.


 Did you know? . . . (2) Hydraulic diameter vs Equivalent diameter!  


For duct with shapes that are not round, hydraulic diameter does not equal to equivalent diameter. For circular duct, hydraulic diameter is the same as the diameter of a round duct.


For any duct shapes, hydraulic diameter = 4 x cross-sectional area / perimeter. Ductulator Plus uses this approach to find duct sizes.


For rectangular duct, equivalent diameter = 1.30 x {(Width x Height)0.625 / (Width + Height)0.25}. 


For oval duct, equivalent diameter = 1.55 x (cross-sectional area)0.625 / (perimeter)0.25.


 Example: Duct Sizing at job site (in SI units)  


An existing duct 600mm (W) x 500mm (H) carrying an airflow of 8000 CMH needs to be flattened to 300mm (H) to achieve the desired ceiling height.
Find the new duct size based on the existing duct friction loss rate.



Step 1: Find duct friction loss rate for the existing duct.

Step 2: Calculate new duct size with the given height constraint.


The following results are computed by the Ductulator Plus:


 Step 1 results

 Step 2 results

Duct Friction Loss Rate calculations


Retangular Duct sizing......
Duct height =500 mm
Duct width =600 mm
Air volume =8000 CMH
Duct roughness=0.09 mm
Duct velocity =7.41 m/s
Friction loss rate=0.9781 Pa/m

(1) Flow area, A = 0.300 sq.m
(2) Hydraulic dia, Dh = 545.5 mm
(3) Reynolds nos, Re = 268,283
(4) Relative roughness, e/Dh = 0.000165
(5) Friction factor, ff = 0.016205

(6) Velocity pressure, Pv = 33.03 Pa
(friction factor solved by ColeBrook equation)

Equal Friction Method calculations


Retangular Duct sizing......
Friction loss rate =0.9781 Pa/m
Duct roughness, e =0.09 mm
Air volume =8000 CMH
Duct height =300 mm
Duct width =1100 mm

Duct velocity =6.74 m/s


(1) Flow area, A = 0.330 sq.m
(2) Hydraulic dia, Dh = 471.2 mm
(3) Reynolds nos, Re = 210,908
(4) Relative roughness, e/Dh = 0.000191
(5) Friction factor, ff = 0.016916

(6) Velocity pressure, Pv = 27.34 Pa
(friction factor solved by ColeBrook equation)

 Note: For air balancing by Proportional Method, see  AirTAB superEZ.



Experience yourself the power of Ductulator plus+

Price: USD 19.90 (2014 sale



Download now:

product detail 


OS requirements: Windows Mobile, Windows.


For Android OS, see                            


Accept: credit card payment with PayPal 


1) Pay & instant Download via Click2Sell service:



Note: check your email /junk mail after making payment.

in SI & IP units


 view Ductulator+ explained




 Duct Sizing


 material selection



Velocity Guide



Louvre Sizer



 Sheet Metal Gauge




Fan Motor kW



Psychrometric Air Properties calculator (rhoAIR)