diff --git a/src/lib.rs b/src/lib.rs
index ea8cfde..e1fa05d 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -9,16 +9,10 @@ use std::{
     process::Command,
 };
 
-pub const DEFAULT_BUF_SIZE: usize = 8 * 1024;
-pub const SIZE_KB: i64 = 1024;
-pub const SIZE_MB: i64 = SIZE_KB * SIZE_KB;
-pub const SIZE_GB: i64 = SIZE_MB * SIZE_KB;
-pub const SIZE_PB: i64 = SIZE_GB * SIZE_KB;
-pub const SIZE_TB: i64 = SIZE_PB * SIZE_KB;
-
 pub mod util_io;
 pub mod util_os;
 pub mod util_msg;
+pub mod util_size;
 
 pub type XResult<T> = Result<T, Box<dyn std::error::Error>>;
 
@@ -114,44 +108,6 @@ pub fn new_box_ioerror(m: &str) -> Box<dyn std::error::Error> {
     Box::new(Error::new(ErrorKind::Other, m))
 }
 
-pub fn parse_size(size: &str) -> XResult<i64> {
-    let lower_size = size.to_lowercase();
-    let no_last_b_size = if lower_size.ends_with("b") {
-        &lower_size[0..lower_size.len()-1]
-    } else {
-        &lower_size
-    };
-    if no_last_b_size.ends_with("k") {
-        return Ok((SIZE_KB as f64 * no_last_b_size[0..no_last_b_size.len()-1].parse::<f64>()?) as i64);
-    } else if no_last_b_size.ends_with("m") {
-        return Ok((SIZE_MB as f64 * no_last_b_size[0..no_last_b_size.len()-1].parse::<f64>()?) as i64);
-    } else if no_last_b_size.ends_with("g") {
-        return Ok((SIZE_GB as f64 * no_last_b_size[0..no_last_b_size.len()-1].parse::<f64>()?) as i64);
-    } else if no_last_b_size.ends_with("t") {
-        return Ok((SIZE_TB as f64 * no_last_b_size[0..no_last_b_size.len()-1].parse::<f64>()?) as i64);
-    } else if no_last_b_size.ends_with("p") {
-        return Ok((SIZE_PB as f64 * no_last_b_size[0..no_last_b_size.len()-1].parse::<f64>()?) as i64);
-    }
-
-    Ok(no_last_b_size.parse::<i64>()?)
-}
-
-pub fn get_display_size(size: i64) -> String {
-    if size < SIZE_KB {
-        return size.to_string();
-    } else if size < SIZE_MB {
-        return format!("{:.*}KB", 2, (size as f64) / 1024.);
-    } else if size < SIZE_GB {
-        return format!("{:.*}MB", 2, (size as f64) / 1024. / 1024.);
-    } else if size < SIZE_TB {
-        return format!("{:.*}GB", 2, (size as f64) / 1024. / 1024. / 1024.);
-    } else if size < SIZE_PB {
-        return format!("{:.*}TB", 2, (size as f64) / 1024. / 1024. / 1024. / 1024.);
-    } else {
-        return format!("{:.*}PB", 2, (size as f64) / 1024. / 1024. / 1024. / 1024. / 1024.);
-    }
-}
-
 pub fn run_command_and_wait(cmd: &mut Command) -> io::Result<()> {
     cmd.spawn()?.wait()?;
     Ok(())
diff --git a/src/util_io.rs b/src/util_io.rs
index a53a3ee..812b528 100644
--- a/src/util_io.rs
+++ b/src/util_io.rs
@@ -4,7 +4,7 @@ use std::{
     time::SystemTime,
 };
 
-use super::get_display_size;
+use super::util_size::get_display_size;
 use super::util_msg::print_lastline;
 
 pub const DEFAULT_BUF_SIZE: usize = 8 * 1024;