Python List index() Method

list.index() finds the position of a value in a list.

Use it when you have a list and want to know where a specific item appears. It returns the index of the first matching item. If the value is not in the list, Python raises a ValueError.

Quick answer

items = ["apple", "banana", "cherry"]
position = items.index("banana")
print(position)  # 1

Use list.index(value) to get the position of the first matching item. It raises ValueError if the item is not found.

What list.index() does

list.index():

  • Finds the position of a value in a list
  • Returns the index of the first matching item
  • Uses zero-based indexing, so the first item is at position 0
  • Works only if the value exists in the list

If you are new to lists, see Python lists explained for beginners.

Basic syntax

The basic form is:

my_list.index(value)

You can also limit the search:

my_list.index(value, start, end)

Here is what each part means:

  • value: the item to search for
  • start: where the search begins
  • end: where the search stops
  • end is not included in the search range

This means Python searches from start up to, but not including, end.

What the return value means

list.index() returns an integer.

That integer is the position of the first match in the list.

Example:

numbers = [10, 20, 30]
result = numbers.index(20)

print(result)

Output:

1

If the same value appears more than once, index() still returns only the first matching position.

Example: find an item in a list

Here is a simple example with strings:

fruits = ["apple", "banana", "cherry"]
position = fruits.index("cherry")

print(position)

Output:

2

In this list:

  • "apple" is at index 0
  • "banana" is at index 1
  • "cherry" is at index 2

So fruits.index("cherry") returns 2.

If you want a task-focused example, see how to find an item in a list in Python.

Example: list with duplicate values

If a list contains the same value more than once, index() returns the first match only.

colors = ["red", "blue", "red", "green"]

print(colors.index("red"))

Output:

0

Even though "red" appears again later, Python returns 0 because that is the first matching position.

If you need to count how many times a value appears, use Python list count() method.

Using start and end

The optional start and end arguments let you search only part of a list.

letters = ["a", "b", "c", "b", "d"]

print(letters.index("b"))        # first match
print(letters.index("b", 2))     # search starting at index 2
print(letters.index("b", 1, 4))  # search from 1 up to 4

Output:

1
3
1

How this works:

  • letters.index("b") searches the whole list and returns the first "b" at index 1
  • letters.index("b", 2) starts searching at index 2, so it finds the next "b" at index 3
  • letters.index("b", 1, 4) searches indexes 1, 2, and 3

This is useful when you want to skip earlier items and find a later match.

What happens if the value is missing

If the value is not in the list, Python raises a ValueError.

Example:

items = ["apple", "banana", "cherry"]
print(items.index("orange"))

This causes an error because "orange" is not in the list.

A safer approach is to check first:

items = ["apple", "banana", "cherry"]
search_value = "orange"

if search_value in items:
    print(items.index(search_value))
else:
    print("Item not found")

Output:

Item not found

This avoids the error and makes your code easier to understand.

If you want more help with this kind of problem, see ValueError in Python: causes and fixes.

Common beginner mistakes

Here are some common problems when using list.index():

  • Thinking index() returns -1 if the item is missing
    Python does not return -1. It raises ValueError.
  • Confusing the item value with the item position
    my_list.index("banana") returns the position of "banana", not the value itself.
  • Using index[] instead of index()
    This is a method call, so you must use parentheses.
    Correct:
    items.index("banana")

    Wrong:
    items.index["banana"]
  • Searching with the wrong type
    "3" and 3 are different values in Python.
    numbers = [1, 2, 3]
print("3" in numbers)  # False

If your code is not working, these quick checks can help:

print(my_list)
print(type(search_value))
print(search_value in my_list)
print(my_list.index(search_value))

Be careful with the last line. It will still raise an error if the value is missing.

Common causes of problems include:

  • The searched value is not in the list
  • The value exists but has a different type, such as "3" instead of 3
  • The code expects all matches, but index() returns only the first one
  • Parentheses were forgotten when calling the method

When to use index()

Use index() when:

  • You need the position of a known value
  • You are working with a small list
  • You only need the first matching position

Do not use it when you need every matching position. In that case, a loop or list comprehension is a better choice.

FAQ

What does list.index() return in Python?

It returns the index of the first matching item in the list.

Does list.index() return -1 if the value is not found?

No. It raises ValueError instead.

Can list.index() find all matching items?

No. It returns only the first match.

Can I search only part of a list with index()?

Yes. You can use the optional start and end arguments.

See also