What Does enumerate() Do in Python? (With Examples)

Wondering what enumerate does in Python? It wraps any iterable and hands you each item together with its position, as an (index, item) pair. So in a for loop you get the counter for free:

for i, park in enumerate(["Yellowstone", "Zion"]):
    print(i, park)      # 0 Yellowstone, then 1 Zion

All the output below is copied from Python 3.12.5 on Windows, and the screenshots show the same runs in Command Prompt.

I’ll show the basic loop, the start argument, why it beats range(len()), using it on strings, dicts and files, and a few tricks with zip().

How enumerate works in a Python for loop

enumerate() produces tuples, and the for i, park in ... line unpacks each one into two variables. Wrapping it in list() shows exactly what’s coming out:

parks = ["Yellowstone", "Yosemite", "Zion"]

for i, park in enumerate(parks):
    print(i, park)

print(list(enumerate(parks)))     # what enumerate actually produces
print(enumerate(parks))           # a lazy enumerate object

Output:

0 Yellowstone
1 Yosemite
2 Zion
[(0, 'Yellowstone'), (1, 'Yosemite'), (2, 'Zion')]
<enumerate object at 0x00000153FC825E90>

Printing the object itself just shows <enumerate object at ...>. It’s lazy, so it makes each pair only when the loop asks for it.

Starting enumerate at 1 (or any number)

Humans count from 1, so numbered lists usually look wrong starting at 0. Pass start=1, or any other integer, as the second argument:

tasks = ["File taxes", "Renew license", "Book flights"]

for n, task in enumerate(tasks, start=1):
    print(f"{n}. {task}")

for n, task in enumerate(tasks, 101):      # start can be any integer
    print(f"Ticket #{n}: {task}")

Output:

1. File taxes
2. Renew license
3. Book flights
Ticket #101: File taxes
Ticket #102: Renew license
Ticket #103: Book flights

Why use enumerate instead of range(len())?

You’ll often see for i in range(len(items)) in older code. It works, but you then need items[i] everywhere. enumerate() gives you the value directly:

prices = [19.99, 5.49, 102.00]

# the old way
for i in range(len(prices)):
    print(i, prices[i])

# the Pythonic way
for i, price in enumerate(prices):
    print(i, price)

# changing items in place still needs the index
for i, price in enumerate(prices):
    prices[i] = round(price * 1.08, 2)      # add 8% tax
print(prices)

Output:

0 19.99
1 5.49
2 102.0
0 19.99
1 5.49
2 102.0
[21.59, 5.93, 110.16]

You still use the index when you change items in place, as in the tax example. For more patterns, see Python for loop with index.

Using enumerate on strings, dictionaries and files

Anything you can loop over works with enumerate(). With a dict, enumerate .items() and unpack the pair in parentheses. With a file, you get line numbers:

for i, letter in enumerate("Ohio"):
    print(i, letter, end="  ")
print()

capitals = {"TX": "Austin", "CA": "Sacramento"}
for i, (state, city) in enumerate(capitals.items(), start=1):
    print(i, state, city)

with open("orders.txt", "w") as f:
    f.write("order 1001\norder 1002\n\norder 1004\n")

with open("orders.txt") as f:
    for line_no, line in enumerate(f, start=1):
        if not line.strip():
            print("blank line at", line_no)

Output:

0 O  1 h  2 i  3 o  
1 TX Austin
2 CA Sacramento
blank line at 3

That line-number trick is my go-to for reporting errors in CSV or log files. Python dictionary index has more on positions in a dict.

enumerate with zip, comprehensions and next()

Combine it with zip() to number two lists at once, or use it in a comprehension to find every index of a value. Remember it’s an iterator, so it only runs once:

scores = [88, 92, 75, 92, 61]

print([i for i, s in enumerate(scores) if s == 92])           # every index of 92
print({name: i for i, name in enumerate(["Ann", "Bo", "Cy"])})  # name -> position

cities = ["Reno", "Mesa", "Waco"]
states = ["NV", "AZ", "TX"]
for i, (city, state) in enumerate(zip(cities, states), start=1):
    print(i, city, state)

numbered = enumerate(scores)
print(next(numbered), next(numbered))    # it's an iterator
print(len(list(numbered)), "left")       # the first two are already used
print(len(list(numbered)), "on a second pass")

Output:

[1, 3]
{'Ann': 0, 'Bo': 1, 'Cy': 2}
1 Reno NV
2 Mesa AZ
3 Waco TX
(0, 88) (1, 92)
3 left
0 on a second pass

If you need to loop twice, call enumerate() again or save list(enumerate(...)) once. The Python zip() function guide covers the zip side.

enumerate() in Python: quick reference

You write	You get
enumerate(items)	(0, first), (1, second), …
enumerate(items, start=1)	(1, first), (2, second), …
list(enumerate(items))	A list of (index, item) tuples
enumerate(d.items())	(0, (key, value)), …
enumerate(zip(a, b))	(0, (a0, b0)), …

A few related loop guides worth a look:

• Python for loop
• Break and continue in Python
• len() function in Python
• What does in mean in Python
• List of lists in Python

Frequently asked questions