Generate QR Codes with Python

Overview

QR codes bridge physical and digital. Python’s qrcode library generates them from any string: URLs, contact info, WiFi credentials, payment links. This recipe covers basic generation, styling, error correction levels, and batch creation.

When to Use

• You need to generate QR codes for URLs or product pages
• You are creating vCard contact cards for print or email
• You want to encode WiFi credentials for guest access
• You need to batch-generate hundreds of QR codes from a CSV

Solution

Basic QR code

import qrcode

img = qrcode.make("https://example.com")
img.save("qr_basic.png")

Custom size and error correction

import qrcode

qr = qrcode.QRCode(
    version=1,  # 1 = 21x21, increases with more data
    error_correction=qrcode.constants.ERROR_CORRECT_H,  # High = 30% recovery
    box_size=10,  # pixel size of each box
    border=4,  # minimum border (quiet zone)
)
qr.add_data("https://example.com/long-url-here")
qr.make(fit=True)

img = qr.make_image(fill_color="black", back_color="white")
img.save("qr_custom.png")

Generate vCard QR code

import qrcode

vcard = """BEGIN:VCARD
VERSION:3.0
FN:Jane Smith
ORG:Acme Corp
TITLE:Software Engineer
TEL:+15551234567
EMAIL:jane@example.com
URL:https://example.com
END:VCARD"""

qr = qrcode.QRCode(error_correction=qrcode.constants.ERROR_CORRECT_M)
qr.add_data(vcard)
qr.make(fit=True)
img = qr.make_image(fill_color="#1a56db", back_color="white")
img.save("qr_vcard.png")

WiFi credentials QR code

import qrcode

wifi = "WIFI:T:WPA;S:MyNetwork;P:MyPassword;;"
qr = qrcode.QRCode(error_correction=qrcode.constants.ERROR_CORRECT_H)
qr.add_data(wifi)
qr.make(fit=True)
img = qr.make_image()
img.save("qr_wifi.png")

Batch generate from CSV

import qrcode
import csv
from pathlib import Path

output_dir = Path("qr_codes")
output_dir.mkdir(exist_ok=True)

with open("urls.csv", newline="") as f:
    reader = csv.DictReader(f)
    for row in reader:
        url = row["url"]
        name = row["name"]
        img = qrcode.make(url)
        img.save(output_dir / f"{name}.png")
        print(f"Generated: {name}.png")

Generate as SVG

import qrcode
import qrcode.image.svg

qr = qrcode.QRCode(image_factory=qrcode.image.svg.SvgImage)
qr.add_data("https://example.com")
qr.make(fit=True)
img = qr.make_image()
img.save("qr_vector.svg")

Explanation

QR codes encode data in a 2D matrix of black and white squares. The version parameter controls the matrix size (1 = 21x21, up to 40 = 177x177). Higher versions hold more data but produce larger images.

Error correction has four levels:

• L (Low): 7% recovery. Smallest QR code for the data.
• M (Medium): 15% recovery. Good default for most uses.
• Q (Quartile): 25% recovery. Use when the code might get partially obscured.
• H (High): 30% recovery. Use for print where ink spread or damage is possible.

The box_size controls pixel dimensions. border (quiet zone) must be at least 4 modules for scanners to detect the QR code reliably.

Variants

Format	Library	Output	Use When
PNG	qrcode + Pillow	Raster image	Web, print
SVG	qrcode.image.svg	Vector image	Print, scaling
PNG with logo	qrcode + Pillow	Branded QR	Marketing

Guidelines

• Use error correction H for print materials. Ink spread can damage the code.
• Keep the quiet zone at 4 or more modules. Scanners need clear borders.
• Test QR codes with multiple scanner apps before printing.
• Use SVG for print. It scales without pixelation at any size.
• Keep URLs short. Use a URL shortener if the encoded string is too long for version 10+.

Common Mistakes

• Using error correction L for print. Ink spread damages low-correction codes.
• Setting border to 0. Scanners cannot detect the QR code without a quiet zone.
• Encoding too much data. URLs over 100 characters push the version high and make the code hard to scan.
• Not testing on physical prints. Screen previews do not reflect scanning conditions.
• Using colored fills with low contrast. Scanners need dark modules on light backgrounds.

Frequently Asked Questions

Can I add a logo in the center of a QR code?

Yes, but only with error correction H. The logo covers part of the data, and the 30% recovery compensates. Use Pillow to paste the logo image onto the center of the QR code.

How much data can a QR code hold?

Up to 2,953 bytes (alphanumeric) or 4,296 digits at version 40 with error correction L. Practical limits are lower because high-density codes are hard to scan with phone cameras.

How do I decode a QR code from an image?

Use pyzbar with Pillow:

from pyzbar.pyzbar import decode
from PIL import Image

results = decode(Image.open("qr_code.png"))
for r in results:
    print(r.data.decode())

Is the qrcode library free for commercial use?

Yes. The qrcode library is BSD-licensed. You can use it in commercial projects without restrictions.