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FullForm[expr]

prints as the full form of expr, with no special syntax.

Details and Options
Details and Options Details and Options
Examples  
Basic Examples  
Scope  
Basic Objects  
Special Input Forms  
Special Output Forms  
Options  
NumberMarks  
Applications  
Properties & Relations  
Possible Issues  
See Also
Tech Notes
Related Guides
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FullForm

FullForm[expr]

prints as the full form of expr, with no special syntax.

Details and Options

  • FullForm always effectively uses "PrintableASCII" as the setting for $CharacterEncoding.
  • The option NumberMarks can be used to specify whether ` marks should be used to indicate type, precision, or accuracy of approximate numbers. »
  • The typeset form of FullForm[expr] is interpreted the same as expr when used in input. »
  • When an input evaluates to FullForm[expr], FullForm does not appear in the output. »

Examples

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Basic Examples  (2)

FullForm of a typeset expression:

Wolfram Language code: FullForm[(x/Sqrt[5]) + y^2 + 1 / z]

FullForm of a graphic:

Wolfram Language code: [image]//FullForm

Scope  (8)

Basic Objects  (2)

Integer, Rational, Real, and Complex numbers:

Wolfram Language code: Map[FullForm, {123, 1 / 23, 1.23, 1 + 23I}]

Arbitrary-precision Real and Complex numbers:

Wolfram Language code: FullForm /@ N[{10 / 3, 10 / 3I}, 20]

Special constants:

Wolfram Language code: FullForm /@ {I, π, E}

Characters and strings of characters:

Wolfram Language code: FullForm /@ {"a", "α", "⊕"}

Control characters for strings:

Wolfram Language code: FullForm["A first line A second line"]

Special Input Forms  (4)

Different inputs interpreted as Power expressions:

Wolfram Language code: FullForm /@ {a ^ x, a^x, Sqrt[a], Sqrt[a], a^(1/(3)), Exp[x], 1 / x, (1/x)}

Special typeset expressions:

Wolfram Language code: FullForm /@ {y'[x], ∫y[x]ⅆx, Subsuperscript[∑, k = 1, n]y[k], Subsuperscript[∏, k = 1, n]y[k], x∈Reals, x∧y∨z}

Different list structures:

Wolfram Language code: FullForm[{1, 2, 3}]
Wolfram Language code: FullForm /@ {(| | | | | - | - | - | | a | b | c | | d | e | f |), {{a, b, c}, {d, e, f}}}

Input without special interpretation:

Wolfram Language code: FullForm /@ {Subscript[x, a], Overscript[x, a], Underscript[x, a]}

With special characters in the same positions, there may be special interpretations:

Wolfram Language code: FullForm /@ {Subscript[x, - ], Overscript[x, _], Underscript[x, _]}

In the case of superscripts, most things get interpreted as Power:

Wolfram Language code: FullForm /@ {x^a, Subsuperscript[x, b, a], x^†}

Special Output Forms  (2)

Some objects use a special output representation:

Wolfram Language code: Series[Sin[x], {x, 0, 3}]
Wolfram Language code: FullForm[%]

Some objects use an elided output representation:

Wolfram Language code: i = Interpolation[{1, 2, 3, 1}]
Wolfram Language code: s = SparseArray[{{1, 2} -> 1}, {5, 5}]

The elided parts are visible in the underlying FullForm:

Wolfram Language code: FullForm[i]
Wolfram Language code: FullForm[s]

Options  (2)

NumberMarks  (2)

Inexact numbers format without number marks by default:

Wolfram Language code: FullForm[4.567]
Wolfram Language code: FullForm[N[10 / 3, 20]]

The same numbers without number marks:

Wolfram Language code: FullForm[4.567, NumberMarks -> False]
Wolfram Language code: FullForm[N[10 / 3, 20], NumberMarks -> False]

A mixed symbolic and numeric expression:

Wolfram Language code: expr = N[10, 4]Sin[.25x]
Wolfram Language code: FullForm[expr]

Omit all number marks:

Wolfram Language code: FullForm[expr, NumberMarks -> False]

Applications  (4)

The FullForm will show the precedence of operators:

Wolfram Language code: FullForm[a b + c]

Grouping with parentheses affects the precedence:

Wolfram Language code: FullForm[a (b + c)]

See the underlying interpretation for a TraditionalForm output:

Wolfram Language code: TraditionalForm[Sin[I Pi / n]]
Wolfram Language code: FullForm[%]

Perform replacements:

Wolfram Language code: {{a}, b, {{c}}}//FullForm

Replace lists with a new wrapper newhead:

Wolfram Language code: {{a}, b, {{c}}} /. List -> newhead

Multiplications have the head Times:

Wolfram Language code: expr = a + b(c - d)
Wolfram Language code: FullForm[expr]

Find all multiplications in expr:

Wolfram Language code: Cases[expr, _Times, Infinity]

See the underlying expressions:

Wolfram Language code: Map[FullForm, %]

Properties & Relations  (4)

The typeset form of FullForm[expr] is interpreted the same as expr when used in input:

Wolfram Language code: {FullForm[x ^ 2]}

Copy the output and paste it into an input cell. The Power[x,2] is interpreted as x2:

Wolfram Language code: {Power[x, 2]}

When an input evaluates to FullForm[expr], FullForm does not appear in the output:

Wolfram Language code: FullForm[x ^ 2]

Out is assigned the value x2, not FullForm[x^2]:

Wolfram Language code: %

FullForm has linear formatting without special syntax:

Wolfram Language code: FullForm[1 / a + x ^ 2]

InputForm formats as linear input:

Wolfram Language code: InputForm[1 / a + x ^ 2]

TreeForm graphically displays an expression's tree structure:

Wolfram Language code: FullForm[1 / (a + b)x ^ 2]
Wolfram Language code: TreeForm[1 / (a + b)x ^ 2]

Possible Issues  (2)

Even when an output omits FullForm from the top level, it is not stripped from subexpressions:

Wolfram Language code: e = FullForm[x ^ 2]

The output does not have FullForm in it:

Wolfram Language code: %

However, the variable e does have FullForm in it, which may affect subsequent evaluations:

Wolfram Language code: FullForm[e]

The product is not evaluated due to the intervening FullForm:

Wolfram Language code: x * e

Assign variables first and then apply FullForm to the result to maintain computability:

Wolfram Language code: (f = x ^ 2)//FullForm
Wolfram Language code: x * f

Pattern matching is based on the FullForm:

Wolfram Language code: 1 / Sqrt[2] /. {Sqrt[2] -> sq2}

The previous fraction is represented as a single Power expression:

Wolfram Language code: 1 / Sqrt[2]//FullForm

Perform the desired replacement:

Wolfram Language code: 1 / Sqrt[2] /. Power[2, -1 / 2] -> 1 / sq2
Wolfram Research (1988), FullForm, Wolfram Language function, https://reference.wolfram.com/language/ref/FullForm.html (updated 2003).

Text

Wolfram Research (1988), FullForm, Wolfram Language function, https://reference.wolfram.com/language/ref/FullForm.html (updated 2003).

CMS

Wolfram Language. 1988. "FullForm." Wolfram Language & System Documentation Center. Wolfram Research. Last Modified 2003. https://reference.wolfram.com/language/ref/FullForm.html.

APA

Wolfram Language. (1988). FullForm. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/FullForm.html

BibTeX

@misc{reference.wolfram_2026_fullform, author="Wolfram Research", title="{FullForm}", year="2003", howpublished="\url{https://reference.wolfram.com/language/ref/FullForm.html}", note=[Accessed: 13-June-2026]}

BibLaTeX

@online{reference.wolfram_2026_fullform, organization={Wolfram Research}, title={FullForm}, year={2003}, url={https://reference.wolfram.com/language/ref/FullForm.html}, note=[Accessed: 13-June-2026]}