Tech With Galvan

Introduction

In this guide you will build an interactive Age Calculator web app using Python and Streamlit. The app calculates your exact age in years, months, and days — and even shows fun insights like the total number of days you have been alive.

Features

Date Picker — Users select their birthdate with a simple calendar widget.

Age Breakdown — Displays years, months, and days in a clean metric layout.

Special Messages — Dynamic messages based on age range (minor, adult, senior).

Fun Fact — Shows the total number of days the user has been alive.

Prerequisites

Make sure you have the following installed before you begin:

Python 3.8+ — Download from python.org.

Streamlit — Install with pip:

code

pip install streamlit

Step 1: Create the Python Script

Create a new file called age_calculator_app.py and paste in the following code:

code

import streamlit as st
from datetime import datetime, date

st.set_page_config(page_title="Age Calculator", layout="centered", page_icon="🎂")
st.title("🎉 Age Calculator App 🎂")

st.sidebar.header("📅 Enter Your Birthdate")
dob = st.sidebar.date_input(
    "Select your date of birth:",
    value=datetime(2000, 1, 1),
    min_value=datetime(1900, 1, 1),
    max_value=datetime.now(),
)

def calculate_age(birthdate):
    today = date.today()
    years = today.year - birthdate.year
    months = today.month - birthdate.month
    days = today.day - birthdate.day
    if days < 0:
        months -= 1
        days += 30
    if months < 0:
        years -= 1
        months += 12
    total_days = (today - birthdate).days
    return years, months, days, total_days

years, months, days, total_days = calculate_age(dob)

col1, col2, col3 = st.columns(3)
col1.metric("Years", years)
col2.metric("Months", months)
col3.metric("Days", days)

st.info(f"You have been alive for **{total_days:,} days**! 🎉")

Step 2: Run the App

Open your terminal, navigate to the folder where you saved the file, and run:

code

streamlit run age_calculator_app.py

Step 3: Use the App

The app will open in your browser automatically. Select your date of birth from the sidebar and the app instantly displays your age in years, months, and days, plus a fun total-days count.

Key Concepts

`st.date_input()` — Renders a calendar date picker widget.

`calculate_age()` — Custom function that computes years, months, days, and total days.

`st.columns()` — Splits the page into a clean 3-column grid.

`st.metric()` — Renders each number in a styled metric card.

What to Try Next

Add a zodiac sign display based on the birth date.

Show a countdown to the user's next birthday.

Add a download button to save the result using st.download_button().