 Feedback

Autodesk® Revit’s basic formulae ## Date

The following are the commonly used formulas that we have been using for several years. Here we include the basic functions that allow us to develop simple and complex formulas.

#### Basic operations

Functions

The following characters tell Revit what to do between 2 values.

Command in Revit

+

*

/

=

<

>

^

Sum

Sum

Subtract

Multiplication

Division

Equal

Less than

More than

Exponentiation

Declarations

The following statements tell Revit whether the formula will be a Boolean, alternative, or rounding. These are included at the beginning of the formula.

Command in Revit

IF()

AND()

OR()

NOT()

ROUND()

ROUNDDOWN()

ROUNDUP()

LOG()

Definition

Conditional declaration

Declaration to have an alternative

Opposite / flase declaration

Rounding

Rounding down

Rounding up

Logarithm

## Formulae

The following formulas outline the basic operations that can be used in Revit.

Conditional formula

A formula that gives a numerical value based on the condition being true.

Formula

``IF ([Conditional], [Value if true] , [Value if false])``

Example

X = IF ( A > B , Z , Y )

Conditional formula with text

A formula that gives a text value based on whether the condition is true or false.

Note: The text value as a result must be enclosed in quotation marks.

Formula

``IF ([Conditional], [Value if true] , [Value if false])``

Example

X = IF ( A > B , “True” , “False” )

Nested conditional formula IF() and AND()

A formula that gives a result based on two conditionals.

Formula

``IF( AND( [Conditional 1], [Conditional 2]) , [Value if true] , [Value if false])``

Example

X = IF ( AND( A > B, A > C) , “True” , “False” )

Nested conditional formula IF() and OR()

A formula that gives a result based on one of two conditions being true.

Formula

``IF( AND( [Conditional Alternative 1], [Conditional Alternative 2]) , [Value if any alternative is true] , [Value if no alternatives are true])``

Example

X = IF ( OR( A > B, A > C) , “True” , “False” )

Exponential

Formula that returns the exponential of a value to the indicated power.

Formula

``[Numeric Value] ^ [Exponential]``

Example

X = Y ^ E

Exponential of E

Formula that returns the exponential E of a value.

Formula

``exp([Numeric Value])``

Example

X = exp(N)

Circles

Formula to calculate the value of the circumference and/or area of a circle.

Formula

``````Circumference = pi() * ([Radio] * 2)
Area = pi() * [Radio] ^ 2``````

Example

(Circumference) X = pi() * (Radius * 2)

(Area) X = pi() * Radius ^ 2

Square Root

Formula to calculate the square root of a numerical value.

Formula

``sqrt([Numeric Value])``

Example

X = sqrt(N)

Force (Yes/No) parameters to Yes

Formula that blocks a parameter to check (Yes)

Formula

``[1 < 2] , [1 = 1]``

Example

X = 1 < 2 , X = 1 = 1

Force (Yes/No) parameters to No

Formula that blocks a parameter to uncheck (No)

Formula

``[1 > 2] , [1 = 0]``

Example

X = 1 > 2 , X = 1 = 0

## Trigonometry with Right Triangles

The following formulas help us to calculate the values of angles and lengths of a triangle knowing 2 values of the triangle.

Known: a + b

Formula

``c = sqrt(a ^ 2 + b ^ 2)``

A = atan(a / b)

B = atan(b / a)

Known: a + c

Formula

``b = sqrt(c ^ 2 - a ^ 2)``

A = asin(a / c)

B = acos(a / c)

Known: b + c

Formula

A = acos(b / c)

``a = sqrt(c ^ 2 - b ^ 2)``

B = asin(b / c)

Known: c + A

Formula

``a = c * sin(A)``

b = c * cos(A)

B = 90° – A

Known: c + B

Formula

``a = c * cos(B)``

b = c * sin(B)

A = 90° – B

Known: a + B

Formula

``b = a * tan(B)``

c = a / cos(B)

A = 90° – B

Known: b + A

Formula

``a = b * tan(A)``

c = b / cos(A)

B = 90° – A

Known: a + A

Formula

``b = a / tan(A)``

c = a / sin(A)

B = 90° – A

Known: b + B

Formula

``a = b / tan(B)``

c = b / sin(B)

A = 90° – B

We hope you find this list useful.

If there is a formula you need, please describe it in the comments…