Python zip() Function

Q: What happens if the lists passed to zip() have different lengths?

By default `zip()` stops at the shortest list and ignores the rest. Use `strict=True` to raise a `ValueError` instead.

Q: How do I unzip a list of tuples in Python?

Use `zip(*pairs)`. The star unpacks the list of tuples so that `zip()` regroups them into one tuple per position.

By Yogesh Sharma (LinkedIn) · Every code example is run and checked on Python 3.13 (how we test) · Last updated 21 Oct 2026

Short answer

zip(*iterables, strict=False) combines items from several iterables into tuples, stopping when the shortest one runs out.

zip() is the tool for walking two or more sequences side by side: names with scores, keys with values, x-coordinates with y-coordinates. Each loop step receives one tuple holding the matching item from every iterable.

Like enumerate(), zip() returns a lazy iterator. Wrap it in list() or dict() to keep the result. See the lesson on enumerate and zip for more patterns.

Quick facts
Syntax	`zip(*iterables, strict=False)`
Parameters	`*iterables`: any number of iterables; `strict`: if `True`, raise `ValueError` when lengths differ (Python 3.10+)
Returns	A `zip` iterator of tuples
Default with unequal lengths	Stops silently at the shortest iterable
Time complexity	O(1) per tuple, O(n) overall

How zip() pairs items together

The first tuple holds the first item of every iterable, the second tuple holds the second items, and so on. With two lists of three items you get three pairs.

Python

names = ["Asha", "Ravi", "Meera"]
marks = [88, 92, 79]
print(list(zip(names, marks)))

In a loop you normally unpack the tuple: for name, mark in zip(names, marks):.

What zip() does when lengths differ

By default zip() stops as soon as one iterable is exhausted, so extra items in longer ones are dropped without any warning. That is handy when you want it, and a quiet source of bugs when you don't.

Pass strict=True (Python 3.10 and newer) to turn a length mismatch into a ValueError. If you want to keep the longer data and fill the gaps, use itertools.zip_longest, covered in the itertools lesson.

Call	Lengths 3 and 2	Result
`zip(a, b)`	Unequal	Two tuples; the third item of `a` is dropped
`zip(a, b, strict=True)`	Unequal	`ValueError` while iterating
`zip_longest(a, b)`	Unequal	Three tuples, filled with `None`

Unzipping with zip(*pairs)

The * operator spreads a list of tuples into separate arguments, and zip() then regroups them by position. This turns a list of pairs back into separate sequences. See unpacking for how the star works.

Python

pairs = [("a", 1), ("b", 2), ("c", 3)]
letters, numbers = zip(*pairs)
print(letters)
print(numbers)

Examples you can run

Press Run, then edit the code and run it again.

Loop over two lists together

Each step unpacks one name and one mark.

Loop over two lists together

names = ["Asha", "Ravi", "Meera"]
marks = [88, 92, 79]
for name, mark in zip(names, marks):
    print(name, mark)

Expected outputAsha 88
Ravi 92
Meera 79

Build a dictionary from two lists

dict(zip(keys, values)) is the standard way to combine them.

Build a dictionary from two lists

fields = ["id", "item", "qty"]
values = [101, "pen", 3]
print(dict(zip(fields, values)))

Expected output{'id': 101, 'item': 'pen', 'qty': 3}

Catch mismatched lengths with strict=True

The error is raised while iterating, once one list runs out early.

Catch mismatched lengths with strict=True

a = [1, 2, 3]
b = [10, 20]
try:
    print(list(zip(a, b, strict=True)))
except ValueError as e:
    print(e)

Expected outputzip() argument 2 is shorter than argument 1

Compute with paired values

Combine zip() with a comprehension to calculate line totals.

Compute with paired values

prices = [2.5, 4.0, 1.5]
qty = [4, 2, 10]
totals = [p * q for p, q in zip(prices, qty)]
print(totals)
print(sum(totals))

Expected output[10.0, 8.0, 15.0]
33.0

Common mistakes

Reusing an exhausted zip

✗ Wrong

z = zip([1, 2], [3, 4])
print(list(z))
print(list(z))

The second print shows `[]` because a zip object can be consumed only once.

✓ Right

z = list(zip([1, 2], [3, 4]))
print(z)
print(z)

Store the result with list() if you need it more than once, or create a new zip() each time.

Losing data to unequal lengths

✗ Wrong

names = ["Asha", "Ravi", "Meera"]
marks = [88, 92]
print(list(zip(names, marks)))

No error, but Meera is silently dropped: `[('Asha', 88), ('Ravi', 92)]`

✓ Right

names = ["Asha", "Ravi", "Meera"]
marks = [88, 92]
try:
    print(list(zip(names, marks, strict=True)))
except ValueError:
    print("length mismatch")

Use strict=True to catch the mismatch, or zip_longest to keep every name.

Indexing a zip object

✗ Wrong

pairs = zip([1, 2], [3, 4])
print(pairs[0])

TypeError: 'zip' object is not subscriptable

✓ Right

pairs = list(zip([1, 2], [3, 4]))
print(pairs[0])

Convert to a list before indexing.

Python zip() Function: questions people ask

What does zip() do in Python?

It pairs up items from two or more iterables by position and returns an iterator of tuples. The first tuple holds every first item, the second holds every second item, and so on.

What happens if the lists passed to zip() have different lengths?

By default zip() stops at the shortest list and ignores the rest. Use strict=True to raise a ValueError instead.

How do I unzip a list of tuples in Python?

Use zip(*pairs). The star unpacks the list of tuples so that zip() regroups them into one tuple per position.

Keep learning

Step-by-step lessons:
Python enumerate() and zip()Python for Loops Python Dictionaries

More in built-in functions:
Python print() Function Python len() Function Python range() Function Python type() Function Python int() Function Python float() Function Python str() Function Python input() Function See all →