BytesToStringConverter.cs

using System;
using System.Globalization;
using System.Windows.Data;

namespace NodaStack
{
    public class BytesToStringConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            if (value is long bytes)
            {
                return FormatFileSize(bytes);
            }
            return "0 B";
        }

        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            throw new NotImplementedException();
        }

        private string FormatFileSize(long bytes)
        {
            string[] suffixes = { "B", "KB", "MB", "GB", "TB" };
            double size = bytes;
            int suffixIndex = 0;

            while (size >= 1024 && suffixIndex < suffixes.Length - 1)
            {
                size /= 1024;
                suffixIndex++;
            }

            return $"{size:0.##} {suffixes[suffixIndex]}";
        }
    }
}