How to Write a String to a File in Python

To write a string to a file in Python, open the file in write mode and call write(): with open("file.txt", "w", encoding="utf-8") as f: f.write(text). Use mode "a" to append instead of overwriting, add \n for new lines, and convert numbers with str() first. This guide covers every way to write a string to a file in Python, including print(file=...) and pathlib, the file modes, newlines, encodings, bytes, and the errors you are most likely to hit.

All examples were run with Python 3.12.5 in the Windows Command Prompt; after each script, type shows what actually ended up in the file. Reference: open() and Reading and Writing Files in the Python docs.

Write a string to a file

text = "Hello from Python!"

with open("greeting.txt", "w", encoding="utf-8") as f:
    f.write(text)

print("Saved", len(text), "characters to greeting.txt")

Command Prompt output (the script, then type showing the file):

Saved 18 characters to greeting.txt
Hello from Python!

• "w" creates the file, or empties it if it already exists.
• The with block closes the file automatically, even if an error happens. (Without it, you must call f.close(), with parentheses.)
• Always pass encoding="utf-8"; otherwise Python uses the system default, which on Windows may not handle every character.
• write() returns the number of characters written.

Write a string with newlines

write() writes exactly what you give it; it never adds a line break. Add \n yourself, or use print(..., file=f), which ends the line for you:

with open("notes.txt", "w", encoding="utf-8") as f:
    f.write("First line")                 # write() adds no newline
    f.write("Still the first line\n")    # add \n yourself
    f.write("Second line\n")
    print("Third line", file=f)           # print() adds the newline for you

with open("notes.txt", encoding="utf-8") as f:
    print(repr(f.read()))

Command Prompt output (the script, then type showing the file):

'First lineStill the first line\nSecond line\nThird line\n'
First lineStill the first line
Second line
Third line

Overwrite, append or create only: the file modes

The second argument of open() decides what happens to existing content:

from pathlib import Path

with open("log.txt", "w", encoding="utf-8") as f:     # "w": create or overwrite
    f.write("run 1\n")
with open("log.txt", "w", encoding="utf-8") as f:     # overwrite again: run 1 is gone
    f.write("run 2\n")
with open("log.txt", "a", encoding="utf-8") as f:     # "a": add to the end
    f.write("run 3 (appended)\n")

try:
    with open("log.txt", "x", encoding="utf-8") as f:  # "x": only create, never overwrite
        f.write("run 4\n")
except FileExistsError as e:
    print("FileExistsError:", e)

print(Path("log.txt").read_text(encoding="utf-8"))

Command Prompt output (the script, then type showing the file):

FileExistsError: [Errno 17] File exists: 'log.txt'
run 2
run 3 (appended)
run 2
run 3 (appended)

Mode	If the file exists	If it does not exist
"w"	Empties it, then writes	Creates it
"a"	Writes at the end	Creates it
"x"	Raises FileExistsError	Creates it
"r+"	Reads and writes from the start (no truncation)	Raises FileNotFoundError

Write a string with pathlib (one line)

Path.write_text() opens, writes and closes the file in one call. It always overwrites:

from pathlib import Path

report = Path("report.txt")
count = report.write_text("Total sales: 1,245\nTop region: Texas\n", encoding="utf-8")
print("characters written:", count)
print(report.read_text(encoding="utf-8"), end="")
print("size on disk:", report.stat().st_size, "bytes")

Command Prompt output (the script, then type showing the file):

characters written: 37
Total sales: 1,245
Top region: Texas
size on disk: 39 bytes
Total sales: 1,245
Top region: Texas

The text is 37 characters but 39 bytes on disk on Windows: each \n is saved as the two bytes \r\n (see the last section).

Write several strings or a list

Join the strings into one, or pass them to writelines(), which, despite its name, does not add line breaks either:

cities = ["Austin", "Denver", "Seattle"]

with open("cities.txt", "w", encoding="utf-8") as f:
    f.write("\n".join(cities) + "\n")                  # one string, joined

with open("cities2.txt", "w", encoding="utf-8") as f:
    f.writelines(city + "\n" for city in cities)       # writelines adds no newlines itself

with open("cities2.txt", encoding="utf-8") as f:
    print(f.read().splitlines())

Command Prompt output (the script, then type showing the file):

['Austin', 'Denver', 'Seattle']
Austin
Denver
Seattle

More options in write multiple lines to a file in Python and write a list to a file.

Write numbers and other values

write() only accepts strings. Convert other values with str() or format them with an f-string:

price = 19.99
qty = 3

with open("order.txt", "w", encoding="utf-8") as f:
    try:
        f.write(qty)                                     # write() only accepts str
    except TypeError as e:
        print("TypeError:", e)
    f.write(str(qty) + "\n")                             # convert with str()
    f.write(f"{qty} x ${price:.2f} = ${qty * price:.2f}\n")   # or use an f-string

Command Prompt output (the script, then type showing the file):

TypeError: write() argument must be str, not int
3
3 x $19.99 = $59.97

To save variables of any type (and read them back), see write a variable to a file in Python.

Encoding: accents, symbols and emoji

Write non-English text with encoding="utf-8". A narrower encoding like ASCII fails on the first character it cannot represent:

text = "Café in São Paulo costs €4 ☕"

with open("utf8.txt", "w", encoding="utf-8") as f:
    f.write(text)

try:
    with open("ascii.txt", "w", encoding="ascii") as f:
        f.write(text)
except UnicodeEncodeError as e:
    print("UnicodeEncodeError:", e.reason, "for", repr(e.object[e.start:e.end]))

with open("utf8.txt", encoding="utf-8") as f:
    print(f.read())

Output:

UnicodeEncodeError: ordinal not in range(128) for 'é'
Café in São Paulo costs €4 ☕

Write bytes instead of text

Binary mode ("wb") takes bytes, not str. Convert a string with .encode():

data = "Price: 4 €".encode("utf-8")                   # str -> bytes (the € sign is 3 bytes in UTF-8)

with open("data.bin", "wb") as f:                        # "b": binary mode takes bytes
    count = f.write(data)
print("bytes written:", count)

with open("data.bin", "rb") as f:
    print(f.read())

try:
    with open("other.bin", "wb") as f:
        f.write("a normal string")
except TypeError as e:
    print("TypeError:", e)

Output:

bytes written: 12
b'Price: 4 \xe2\x82\xac'
TypeError: a bytes-like object is required, not 'str'

Line endings on Windows (newline argument)

In text mode on Windows, every \n you write is saved as \r\n. Pass newline="\n" to keep Unix line endings, for example for files used on Linux servers:

with open("windows.txt", "w", encoding="utf-8") as f:
    f.write("a\nb\n")
with open("unix.txt", "w", encoding="utf-8", newline="\n") as f:
    f.write("a\nb\n")

for name in ("windows.txt", "unix.txt"):
    with open(name, "rb") as f:
        print(name, f.read())

Output:

windows.txt b'a\r\nb\r\n'
unix.txt b'a\nb\n'

Related file-handling tutorials:

• Convert a string to CSV in Python
• Write multiple lines to a file
• Read a file line by line in Python
• Python file methods

Frequently asked questions