How to Convert Integer to String in Python

What you’ll build or solve

You’ll convert an integer to a string so you can concatenate it, format messages, or write it to text output.

When this approach works best

Converting an integer to a string works well when you:

• Build messages for users or logs, like User 42 signed in.
• Create filenames or IDs, like report_2026_02_16.txt.
• Join numbers into text output, like turning [1, 2, 3] into "1,2,3".

Skip this approach if you need to do math next. Keep the value as an integer until the final display or export step.

Prerequisites

• Python 3 installed
• You know what an integer and a string are

Step-by-step instructions

1) Convert an integer with str()

str() is the standard way to convert an integer to a string.

count = 42
text = str(count)

print(text)
print(type(text))

What to look for: After conversion, the value prints the same, but the type changes to str.

2) Use f-strings for readable formatting

When you’re building a message, f-strings often read better than manual concatenation. Python converts the integer for you.

user_id = 42
message = f"User {user_id} signed in"

print(message)

Option A (most common): f-string

Option B: format() for older code

user_id = 42
message = "User {} signed in".format(user_id)

print(message)

What to look for: f-strings work in Python 3.6+. If you’re on an older version, use format().

3) Convert while joining or concatenating

If you need to combine an integer with other strings, convert first or use formatting.

page = 3
filename = "page_" + str(page) + ".txt"

print(filename)

For lists of integers, convert each item before joining.

nums = [10, 25, 30]
text = ", ".join(map(str, nums))

print(text)

What to look for: join() only accepts strings, so map(str, nums) prevents TypeError.

Examples you can copy

Example 1: Build a filename with a number

report_num = 7
filename = f"report_{report_num}.txt"
print(filename)

Example 2: Convert an integer for JSON output

JSON requires strings when you want the value stored as text.

import json

user_id = 42
data = {"user_id": str(user_id)}

print(json.dumps(data))

Example 3: Convert command-line input back and forth

You often parse strings into ints, then format them back to strings.

raw = "42"
n = int(raw)
message = f"Parsed number: {n}"

print(message)

Common mistakes and how to fix them

Mistake 1: Concatenating a string and an int

What you might do:

count = 3
text = "Count: " + count

Why it breaks: + only concatenates strings, so Python raises TypeError.

Correct approach:

count = 3
text = "Count: " + str(count)

Or use formatting:

count = 3
text = f"Count: {count}"

Mistake 2: Joining integers without converting

What you might do:

nums = [1, 2, 3]
text = ", ".join(nums)

Why it breaks: join() requires strings, not integers.

Correct approach:

nums = [1, 2, 3]
text = ", ".join(map(str, nums))

Mistake 3: Converting too early and breaking math

What you might do:

a = str(10)
b = str(5)
result = a + b

Why it breaks: String addition concatenates, so you get "105" instead of 15.

Correct approach:

a = 10
b = 5
result = a + b
text = str(result)

Troubleshooting

If you see TypeError: can only concatenate str (not "int") to str, wrap the int in str(...) or use an f-string.

If you see TypeError: sequence item 0: expected str instance, convert items before join(), for example map(str, nums).

If numbers look wrong after combining, check if you converted to a string before finishing arithmetic.

If you get unexpected spaces or punctuation, check the separator you used in join(), such as ", " vs ",".

Quick recap

• Use str(n) to convert an integer to a string.
• Use f-strings like f"Value: {n}" for readable text.
• Convert items before joining: ", ".join(map(str, nums)).
• Keep values as integers for math, then convert at the final display step.
• Fix type errors by converting ints before concatenation or join().