Java tutorial
//package com.java2s; import java.text.DecimalFormat; public class Main { public static String getReadableSize(long bytes, boolean si) { int unit = si ? 1000 : 1024; if (bytes < unit) return bytes + " B"; int exp = (int) (Math.log(bytes) / Math.log(unit)); String pre = (si ? "kMGTPE" : "KMGTPE").charAt(exp - 1) + (si ? "" : "i"); return String.format("%.1f %sB", bytes / Math.pow(unit, exp), pre); } public static String getReadableSize(long bytes) { if (bytes <= 0) return "0"; final String[] units = new String[] { "B", "KB", "MB", "GB", "TB" }; int digitGroups = (int) (Math.log10(bytes) / Math.log10(1024)); return new DecimalFormat("#,##0.#").format(bytes / Math.pow(1024, digitGroups)) + " " + units[digitGroups]; } }