Postfix to Prefix Converter

Last Updated : 2 Mar, 2026

Our Postfix to Prefix converter toolhelps you convert an expression written in postfix notation to its equivalent prefix notation.

Steps to Use Postfix to Prefix Converter

Step 1: Enter your postfix expression in the text box below.

Step 2: Click the "Convert" button.

Step 3: The equivalent prefix expression will be displayed below.

Postfix and Prefix Notation

Infix notation is the standard way we write mathematical expressions, with operators placed between operands (e.g., 2 + 3). Postfix notation puts operators after operands (e.g., 2 3 +), while prefix notation places operators before operands (e.g., + 2 3).

Example:

Postfix: 2 3 +
Prefix: + 2 3

How to Convert Postfix to Prefix Expression

  • Scan the given postfix expression from left to right character by character.
  • If the character is an operand, push it into the stack.
  • But if the character is an operator, pop the top two values from the stack. Concatenate this operator with these two values (operator+2 nd top value+1 st top value) to get a new string.
  • Now push this resulting string back into the stack.
  • Repeat this process until the end of the postfix expression. Now the value in the stack is the desired prefix expression.

Prefix Notation is in the stack that is *+ABc.

Important Notes:

  • This converter supports basic arithmetic operators like addition (+), subtraction (-), multiplication (*), and division (/).
  • The operands should be separated by spaces.
  • Make sure the expression is well-formed and follows postfix notation rules.
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