diff --git a/Cargo.lock b/Cargo.lock
index c189a9e..b43c1e2 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -177,6 +177,12 @@ version = "1.23.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "5c76a5792e44e4abe34d3abf15636779261d45a7450612059293d1d2cfc63422"
 
+[[package]]
+name = "byteorder"
+version = "1.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1fd0f2584146f6f2ef48085050886acf353beff7305ebd1ae69500e27c67f64b"
+
 [[package]]
 name = "byteorder-lite"
 version = "0.1.0"
@@ -704,6 +710,16 @@ dependencies = [
  "cc",
 ]
 
+[[package]]
+name = "ico"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cc50b891e4acf8fe0e71ef88ec43ad82ee07b3810ad09de10f1d01f072ed4b98"
+dependencies = [
+ "byteorder",
+ "png",
+]
+
 [[package]]
 name = "ignore"
 version = "0.4.23"
@@ -1563,6 +1579,7 @@ dependencies = [
  "dotenvy",
  "envy",
  "futures",
+ "ico",
  "lazy_static",
  "phf 0.12.1",
  "phf_codegen 0.12.1",
diff --git a/Cargo.toml b/Cargo.toml
index 92d50fb..1598924 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -25,6 +25,7 @@ phf = { version = "0.12.1", features = ["macros"] }
 phf_codegen = "0.12.1"
 chrono = "0.4.41"
 regex = "1.11.1"
+ico = "0.4.0"
 
 [build-dependencies]
 chrono = "0.4.41"
diff --git a/src/render.rs b/src/render.rs
index e818f04..f14719c 100644
--- a/src/render.rs
+++ b/src/render.rs
@@ -5,6 +5,7 @@ use axum::body::Bytes;
 use axum::http::{header, StatusCode};
 use axum::response::IntoResponse;
 use chrono::{DateTime, Utc};
+use std::io::Cursor;
 
 /// Output format for rendered time banners.
 #[derive(Debug, Clone)]
@@ -41,7 +42,7 @@ impl OutputFormat {
 }
 
 /// Converts SVG to the requested format. PNG requires rasterization.
-fn handle_rasterize(data: String, format: &OutputFormat) -> Result<Bytes, TimeBannerError> {
+pub fn handle_rasterize(data: String, format: &OutputFormat) -> Result<Bytes, TimeBannerError> {
     match format {
         OutputFormat::Svg => Ok(Bytes::from(data)),
         OutputFormat::Png => {
@@ -103,3 +104,50 @@ pub fn render_time_response(
         Err(e) => get_error_response(e).into_response(),
     }
 }
+
+/// Generates PNG bytes for the favicon clock.
+pub fn generate_favicon_png_bytes(time: DateTime<Utc>) -> Result<Vec<u8>, TimeBannerError> {
+    // Build context for rendering
+    let context = RenderContext {
+        value: time,
+        output_form: OutputForm::Clock,
+        output_format: OutputFormat::Png,
+        timezone: None,
+        format: None,
+        now: None,
+    };
+
+    // Render template to SVG
+    let rendered_template = render_template(context)
+        .map_err(|e| TimeBannerError::RenderError(format!("Template rendering failed: {}", e)))?;
+
+    // Convert SVG to PNG
+    let png_bytes = handle_rasterize(rendered_template, &OutputFormat::Png)?;
+
+    Ok(png_bytes.to_vec())
+}
+
+/// Converts PNG bytes to ICO format using the ico crate.
+pub fn convert_png_to_ico(png_bytes: &[u8]) -> Result<Bytes, String> {
+    // Create a new, empty icon collection
+    let mut icon_dir = ico::IconDir::new(ico::ResourceType::Icon);
+
+    // Read PNG data from bytes
+    let cursor = Cursor::new(png_bytes);
+    let image =
+        ico::IconImage::read_png(cursor).map_err(|e| format!("Failed to read PNG data: {}", e))?;
+
+    // Add the image to the icon collection
+    icon_dir.add_entry(
+        ico::IconDirEntry::encode(&image)
+            .map_err(|e| format!("Failed to encode icon entry: {}", e))?,
+    );
+
+    // Write ICO data to a buffer
+    let mut ico_buffer = Vec::new();
+    icon_dir
+        .write(&mut ico_buffer)
+        .map_err(|e| format!("Failed to write ICO data: {}", e))?;
+
+    Ok(Bytes::from(ico_buffer))
+}
diff --git a/src/routes.rs b/src/routes.rs
index e4e5fe4..92dbe63 100644
--- a/src/routes.rs
+++ b/src/routes.rs
@@ -1,10 +1,11 @@
 use crate::duration::parse_time_value;
 use crate::error::{get_error_response, TimeBannerError};
-use crate::render::render_time_response;
+use crate::render::{convert_png_to_ico, generate_favicon_png_bytes, render_time_response};
 use crate::template::OutputForm;
 use crate::utils::parse_path;
 use axum::extract::ConnectInfo;
 use axum::extract::Path;
+use axum::http::{header, StatusCode};
 use axum::response::IntoResponse;
 use std::net::SocketAddr;
 
@@ -53,15 +54,33 @@ pub async fn implicit_handler(Path(path): Path<String>) -> impl IntoResponse {
 
 /// Handles `/favicon.ico` - generates a dynamic clock favicon showing the current time.
 ///
-/// Logs the client IP address and returns a PNG image of an analog clock.
+/// Logs the client IP address and returns an ICO image of an analog clock.
 pub async fn favicon_handler(ConnectInfo(addr): ConnectInfo<SocketAddr>) -> impl IntoResponse {
     let now = chrono::Utc::now();
 
     // Log the IP address for the favicon request
     tracing::info!("Favicon request from IP: {}", addr.ip());
 
-    // Generate clock favicon showing current time
-    render_time_response(now, OutputForm::Clock, "png").into_response()
+    // Generate PNG bytes directly for conversion
+    let png_bytes = match generate_favicon_png_bytes(now) {
+        Ok(bytes) => bytes,
+        Err(e) => return get_error_response(e).into_response(),
+    };
+
+    // Convert PNG to ICO using the ico crate
+    match convert_png_to_ico(&png_bytes) {
+        Ok(ico_bytes) => (
+            StatusCode::OK,
+            [(header::CONTENT_TYPE, "image/x-icon")],
+            ico_bytes,
+        )
+            .into_response(),
+        Err(e) => get_error_response(TimeBannerError::RenderError(format!(
+            "Failed to convert PNG to ICO: {}",
+            e
+        )))
+        .into_response(),
+    }
 }
 
 /// Fallback handler for unmatched routes.