To better understand this section, it is suggested that you first read:  Conditional Actions – Explained and Accessibility

The Compute Value Conditional Action allows a User to build an assortment of arithmetic operations with a variety of operands.

You do not need a trigger field to fire a compute button.  The calculation will fire always on save or if you hit the calculator icon next to the field to be computed. See Fig 2 for example of a calculator for the TrialKit web.

1) When a user selects the Conditional Action type Compute Value

2) A dialog box opens at the bottom of the Conditional Actions Builder as shown in the figure below.

The example below is a compute for age
Fig 1

Operators are as follow:

+ = Addition

- = Subtraction

* = Multiply

/ = Divide

, = Comma (operator)

BMI Sample Formula:

Formula: weight (lb) / [height (in)]2 x 703

Calculate BMI by dividing weight in pounds (lbs) by height in inches (in) squared and multiplying by a conversion factor of 703.

Example: Weight = 220 lbs, Height = 6’0″ (72″)
Calculation: [220 ÷ (72)2] x 703 = 29.8

Fig 2

TrialKit web example of BMI calculation

TrialKit application example of BMI calculation

Another way is to do a scoring field on the web is to add up the fields as shown below in Fig 3 below:

The condition will look like Fig 4 below: Notice how there are no trigger fields used.  The calculator next to the field will compute or on save of form it will always compute.

Some other useful calculations

Body Surface Area (BSA)

(0.007184) * (POW(heightvalue,(.725)) * (POW(weightvalue,(.425))