f-string formatting

Learn number formatting with f"{x:.2f}".

f-strings

An f-string starts with the f prefix and embeds an expression in curly braces {}:

name = "Ayşe"
age = 30
print(f"Merhaba, {name}!")
# Merhaba, Ayşe!
print(f"Yaş: {age + 1}")
# Yaş: 31

The expression inside the f-string is evaluated and its result is embedded in the string. Variables, arithmetic, function calls — any expression works.

Python 3.12 also supports nested f-strings and multi-line f-strings.

Format specifiers

After the colon : inside the curly braces comes a format specifier:

score = 95.567
print(f"{score:.1f}")   # 95.6
print(f"{score:>10}")    #     95.567
print(f"{42:0>5}")       # 00042

.1f means one decimal, >10 means right-align width 10, 0>5 means zero-fill width 5. These specifiers align output and format numbers.

Format specifiers are valuable for table and report output.

Exercise Print score with f-string

Assign "Ayşe" to name. Assign 95.5 to score. Then write print(f"{name}: {score:.1f}").

Show example solution

name = "Ayşe"
score = 95.5
print(f"{name}: {score:.1f}")

Test yourself

Which prints 3.142? (x = 3.14159)
- f'{x:.0f}'
- f'{x:.1f}'
- f'{x:.3f}'
- f'{x:.2f}'
Show answer

f'{x:.3f}' — :.3f shows three decimal places: 3.142.
Match format specifiers

:.2f

Two decimals
:>10

Right-align
:0>5

Zero-fill
:.0f

No decimals

Complete the f-string format

result = f"Score: {score:____}"

Show answer

result = f"Score: {score:.1f}"

Next lesson: sys.argv

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