diff --git a/DiscordChatExporter.Core/DiscordChatExporter.Core.csproj b/DiscordChatExporter.Core/DiscordChatExporter.Core.csproj
index 276e305..9b95e78 100644
--- a/DiscordChatExporter.Core/DiscordChatExporter.Core.csproj
+++ b/DiscordChatExporter.Core/DiscordChatExporter.Core.csproj
@@ -20,6 +20,7 @@
     </ItemGroup>
 
     <ItemGroup>
+        <PackageReference Include="ByteSize" Version="1.3.0" />
         <PackageReference Include="Failsafe" Version="1.0.0" />
         <PackageReference Include="Newtonsoft.Json" Version="12.0.1" />
         <PackageReference Include="Onova" Version="2.2.0" />
diff --git a/DiscordChatExporter.Core/Models/Attachment.cs b/DiscordChatExporter.Core/Models/Attachment.cs
index ebf5f76..f8d6336 100644
--- a/DiscordChatExporter.Core/Models/Attachment.cs
+++ b/DiscordChatExporter.Core/Models/Attachment.cs
@@ -1,4 +1,6 @@
-namespace DiscordChatExporter.Core.Models
+using ByteSizeLib;
+
+namespace DiscordChatExporter.Core.Models
 {
     // https://discordapp.com/developers/docs/resources/channel#attachment-object
 
@@ -16,9 +18,9 @@
 
         public string FileName { get; }
 
-        public long FileSize { get; }
+        public ByteSize FileSize { get; }
 
-        public Attachment(string id, int? width, int? height, string url, string fileName, long fileSize)
+        public Attachment(string id, int? width, int? height, string url, string fileName, ByteSize fileSize)
         {
             Id = id;
             Url = url;
diff --git a/DiscordChatExporter.Core/Resources/ExportTemplates/HtmlShared/Main.html b/DiscordChatExporter.Core/Resources/ExportTemplates/HtmlShared/Main.html
index 85bf3c0..999714e 100644
--- a/DiscordChatExporter.Core/Resources/ExportTemplates/HtmlShared/Main.html
+++ b/DiscordChatExporter.Core/Resources/ExportTemplates/HtmlShared/Main.html
@@ -79,7 +79,7 @@
                                     <img class="chatlog__attachment-thumbnail" src="{{ attachment.Url }}" />
                                 {{~ # Non-image ~}}
                                 {{~ else ~}}
-                                    Attachment: {{ attachment.FileName }} ({{ attachment.FileSize | FormatFileSize }})
+                                    Attachment: {{ attachment.FileName }} ({{ attachment.FileSize }})
                                 {{~ end ~}}
                             </a>
                         </div>
diff --git a/DiscordChatExporter.Core/Services/DataService.Parsers.cs b/DiscordChatExporter.Core/Services/DataService.Parsers.cs
index 4bf89db..837548c 100644
--- a/DiscordChatExporter.Core/Services/DataService.Parsers.cs
+++ b/DiscordChatExporter.Core/Services/DataService.Parsers.cs
@@ -1,6 +1,7 @@
 using System;
 using System.Drawing;
 using System.Linq;
+using ByteSizeLib;
 using DiscordChatExporter.Core.Internal;
 using DiscordChatExporter.Core.Models;
 using Newtonsoft.Json.Linq;
@@ -69,7 +70,9 @@ namespace DiscordChatExporter.Core.Services
             var width = json["width"]?.Value<int>();
             var height = json["height"]?.Value<int>();
             var fileName = json["filename"].Value<string>();
-            var fileSize = json["size"].Value<long>();
+            var fileSizeBytes = json["size"].Value<long>();
+
+            var fileSize = ByteSize.FromBytes(fileSizeBytes);
 
             return new Attachment(id, width, height, url, fileName, fileSize);
         }
diff --git a/DiscordChatExporter.Core/Services/ExportService.TemplateModel.cs b/DiscordChatExporter.Core/Services/ExportService.TemplateModel.cs
index f6a5824..e593cfb 100644
--- a/DiscordChatExporter.Core/Services/ExportService.TemplateModel.cs
+++ b/DiscordChatExporter.Core/Services/ExportService.TemplateModel.cs
@@ -77,21 +77,6 @@ namespace DiscordChatExporter.Core.Services
 
             private string FormatDate(DateTime dateTime) => Format(dateTime, _dateFormat);
 
-            private string FormatFileSize(long fileSize)
-            {
-                string[] units = {"B", "KB", "MB", "GB", "TB", "PB", "EB", "ZB", "YB"};
-                double size = fileSize;
-                var unit = 0;
-
-                while (size >= 1024)
-                {
-                    size /= 1024;
-                    ++unit;
-                }
-
-                return $"{size:0.#} {units[unit]}";
-            }
-
             private string FormatMarkdownPlainText(IEnumerable<Node> nodes)
             {
                 var buffer = new StringBuilder();
@@ -250,7 +235,6 @@ namespace DiscordChatExporter.Core.Services
                 scriptObject.Import(nameof(GroupMessages), new Func<IEnumerable<Message>, IEnumerable<MessageGroup>>(GroupMessages));
                 scriptObject.Import(nameof(Format), new Func<IFormattable, string, string>(Format));
                 scriptObject.Import(nameof(FormatDate), new Func<DateTime, string>(FormatDate));
-                scriptObject.Import(nameof(FormatFileSize), new Func<long, string>(FormatFileSize));
                 scriptObject.Import(nameof(FormatMarkdown), new Func<string, string>(FormatMarkdown));
 
                 return scriptObject;
diff --git a/Readme.md b/Readme.md
index 6a396e4..647f071 100644
--- a/Readme.md
+++ b/Readme.md
@@ -34,6 +34,7 @@ DiscordChatExporter can be used to export message history from a [Discord](https
 - [Scriban](https://github.com/lunet-io/scriban)
 - [CommandLineParser](https://github.com/commandlineparser/commandline)
 - [Ookii.Dialogs](https://github.com/caioproiete/ookii-dialogs-wpf)
+- [ByteSize](https://github.com/omar/ByteSize)
 - [Failsafe](https://github.com/Tyrrrz/Failsafe)
 - [Gress](https://github.com/Tyrrrz/Gress)
 - [Onova](https://github.com/Tyrrrz/Onova)