Python f-Strings

In the last lesson, we learned how to get user input. Now let’s learn how f-strings make output cleaner.

After learning Python Getting User Input, our programs can collect values from a user. Now let’s display those values in clean, readable sentences. In this tutorial, we’ll learn about Python f-strings with easy examples.

🖨️ Let’s Talk About Printing Nicely

We know how to print things. We know how to use variables. But sometimes, printing gets messy. Let me show what I mean.

name = "Alex"
age = 25
city = "London"

Now we want to print: “Alex is 25 years old and lives in London.” How do we do it?

We could do this:

print(name + " is " + str(age) + " years old and lives in " + city)

It works. But look at it. It is ugly. Hard to read. And we have to convert age to a string.

Or we could do this:

print(name, "is", age, "years old and lives in", city)

This is easier. But it adds spaces automatically. And sometimes we don’t want that.

There is a better way. It is called f-strings.

✨ What Is an f-String in Python?

An f-string is a special type of string. It lets us put variables directly inside it. Without any extra work. The “f” stands for “formatted.” Because it formats the string for us. Let me show.

name = "Alex"
age = 25
city = "London"

print(f"{name} is {age} years old and lives in {city}")

Alex is 25 years old and lives in London

Look at that. Clean. Simple. No str(). No + signs. No commas. That is the power of f-strings.

✍️ How to Create an f-String in Python

It is easy. Just put an f before the quotes.

f"This is an f-string"

Then, inside the string, we put variables inside curly braces { }.

name = "Alex"
print(f"Hello, {name}")

Hello, Alex

The {name} gets replaced with the value of name. That’s it. That’s how it works.

🧮 We Can Put Any Expression Inside f-Strings

It is not just variables. We can put any Python expression inside the curly braces.

age = 25
print(f"Next year I will be {age + 1}")

Next year I will be 26

See? It did the math for us.

print(f"2 plus 3 is {2 + 3}")

2 plus 3 is 5

name = "alex"
print(f"Your name in uppercase is {name.upper()}")

Your name in uppercase is ALEX

We can call functions. Do math. Anything.

💬 Python f-Strings: A Real-Life Example

Let’s say we are making a receipt program.

item = "Coffee"
price = 4.50
quantity = 3
total = price * quantity

print(f"Item: {item}")
print(f"Price: ${price}")
print(f"Quantity: {quantity}")
print(f"Total: ${total}")

Item: Coffee
Price: $4.5
Quantity: 3
Total: $13.5

Clean. Readable. Easy. Now compare that to the old way:

print("Item: " + item)
print("Price: $" + str(price))
print("Quantity: " + str(quantity))
print("Total: $" + str(total))

See the difference? The f-string version is much cleaner.

🔢 Formatting Numbers with Python f-Strings

Here is where f-strings get really useful. Sometimes we want to control how a number looks. Like showing only 2 decimal places.

price = 4.5
print(f"Price: ${price:.2f}")

Price: $4.50

See that :.2f? That means: format as a float with 2 decimal places.

Let me break it down:

• : means “here comes the format”
• .2 means “2 decimal places”
• f means “float”

So {price:.2f} gives us 4.50.

If we had 3.14159:

pi = 3.14159
print(f"Pi is approximately {pi:.2f}")

Pi is approximately 3.14

And with 3 decimals:

print(f"Pi is approximately {pi:.3f}")

Pi is approximately 3.142

This is very useful for money and measurements.

🧾 Adding Commas to Big Numbers in Python f-Strings

If we have a big number, we can add commas to make it readable.

population = 8000000000
print(f"World population: {population:,}")

World population: 8,000,000,000

That comma makes a big difference. It is much easier to read.

↔️ Padding and Aligning in Python f-Strings

We can also control the width of the output.

name = "Alex"
print(f"{name:>10}")

      Alex

The >10 means: right-align in a space of 10 characters.

print(f"{name:<10}")

Alex

The <10 means: left-align in a space of 10 characters.

print(f"{name:^10}")

   Alex

The ^10 means: center in a space of 10 characters. This is useful when we want to make tables that line up.

📊 Python f-Strings: A Real-Life Table Example

Let’s make a simple table.

print(f"{'Name':<10} {'Age':>5}")
print("-" * 16)
print(f"{'Alex':<10} {25:>5}")
print(f"{'Sam':<10} {30:>5}")
print(f"{'John':<10} {22:>5}")

Name         Age
----------------
Alex          25
Sam           30
John          22

See how the columns line up? That is the power of formatting.

⚙️ Expressions Inside Python f-Strings

We can put any valid Python expression inside the curly braces.

x = 10
y = 3

print(f"{x} + {y} = {x + y}")
print(f"{x} - {y} = {x - y}")
print(f"{x} * {y} = {x * y}")
print(f"{x} / {y} = {x / y}")

10 + 3 = 13
10 - 3 = 7
10 * 3 = 30
10 / 3 = 3.3333333333333335

We can also use functions and methods.

name = "alex"
print(f"Hello, {name.capitalize()}!")

Hello, Alex!

🪆 Nested Quotes in Python f-Strings

Here is a nice thing about f-strings. We can use different quotes inside and outside.

name = "Alex"
print(f'Hello, {name}')

Single quotes outside. Works fine.

name = "Alex"
print(f"Hello, {name}")

Double quotes outside. Also works. If we need quotes inside the f-string, we use the other type.

name = "Alex"
print(f"He said \"Hello, {name}\"")

He said "Hello, Alex"

Or we use single quotes inside:

print(f'He said "Hello, {name}"')

He said "Hello, Alex"

See? No escape needed.

⚡ Python f-Strings Are Fast

Here is a bonus fact. f-strings are faster than the old ways of formatting strings. There are other ways to format strings in Python:

• % formatting — old style
• .format() — newer style
• f-strings — newest and fastest

f-strings are not just easier to read. They are also faster. So let’s use them. Always.

🧪 A Complete Python f-String Example

Let’s put everything together.

# Get user info
name = input("Enter your name: ")
age = int(input("Enter your age: "))
salary = float(input("Enter your monthly salary: "))

# Calculate yearly salary
yearly = salary * 12

# Print a nice summary
print()
print(f"Hello, {name}!")
print(f"You are {age} years old.")
print(f"Your monthly salary is ${salary:,.2f}")
print(f"Your yearly salary is ${yearly:,.2f}")

Example output:

Enter your name: Alex
Enter your age: 25
Enter your monthly salary: 5000

Hello, Alex!
You are 25 years old.
Your monthly salary is $5,000.00
Your yearly salary is $60,000.00

See how nice that looks? The numbers have commas. The decimals are controlled. The text is clean. That is f-strings in action.

⚠️ Common Mistakes with Python f-Strings

🧭 Mistake 1: Forgetting the f

name = "Alex"
print("{name}")    # This prints {name}, not Alex

{name}

Why? Because there is no f at the start. Python thinks it is a normal string.

So what do we do? We add the f.

print(f"{name}")

🖥 Mistake 2: Using the Wrong Brackets

name = "Alex"
print(f"(name)")    # This prints (name)

So what do we do? We use curly braces.

print(f"{name}")

🐍 Mistake 3: Forgetting to Close the Brace

print(f"Hello, {name")

This gives an error. Because the curly brace is not closed.

So what do we do? We close the brace.

print(f"Hello, {name}")

☕ Mistake 4: Using f-String in Python 2

f-strings were introduced in Python 3.6. If we are using an older version, they will not work. But we should be using Python 3.6 or newer anyway. So this should not be a problem.

Next, we will learn about Python Data Types Overview so we can continue step by step.