Roll your own tqdm-like progress-bar in 3 lines of code

While libraries like tqdm are fantastic, sometimes you just need a quick and simple progress bar for a long-running loop without adding another dependency.

Here’s the complete code snippet:

# 'i' is the loop index and 'total' is the number of items
percent = (i + 1) / total
chars = int(percent * 50) # filled chars count
print(f"Task [{'':=^{chars}}>{'':.^{50-chars}}] {percent*100:.0f} %  ",
    end="\r", flush=True)

This tiny block of code produces a clean, updating progress bar right in your terminal:

Task [==================>...............................] 36 %

The beauty of this solution lies in its simplicity and portability. It uses only built-in Python features, making it trivial to drop into any script. The core technique is also easily adaptable to other languages like C or Java using their respective formatted printing functions.

How It Works

Let’s demystify this “magic” by examining each line.

1. Calculate the Percentage: We compute the completion percentage using (i + 1) / total. The +1 ensures we count from 1% to 100% rather than 0% to 99%.
2. Visual Fill: We determine how many = characters to display by scaling the percentage to our 51-character bar width.
3. The Formatting Magic: This line is the heart of the operation, combining powerful f-string formatting with two special arguments for the print() function.
   The syntax {'':=^{chars}} is a clever trick. It tells Python to create a string of length chars and fill it with the = character. Similarly, {'':.^{50-chars}} creates the “empty” part of the bar using . characters. The > is just a character we use to show the current position.
   flush=True ensures immediate output for smooth animation, while end='\r' returns the cursor to the line start for seamless updates.