Will convert bytes into readable data units.

HumanReadableBytes.cs

using System.Collections.Generic;
using System.Globalization;

namespace HumanReadable
{
	public class HumanReadableBytes
	{
		private readonly Dictionary<Base, Unit[]> _baseUnits = new Dictionary<Base, Unit[]>();
		public int DecimalPoints = 2;
		public int DecimalsAfterPower = 2;
		public string DecimalSeparator = null;
		public string ThousandSeparator = null;

		public HumanReadableBytes()
		{
			Init();
		}

		private void Init()
		{
			_baseUnits.Add(Base.Base10, new Unit[]
			{
				new Unit("byte", "B"),
				new Unit("kilobyte", "kB"),
				new Unit("megabyte", "MB"),
				new Unit("gigabyte", "GB"),
				new Unit("terrabyte", "TB"),
				new Unit("petabyte", "PB")
			});
			_baseUnits.Add(Base.Base2, new Unit[]
			{
				new Unit("byte", "B"),
				new Unit("kibibyte", "KiB"),
				new Unit("mebibyte", "MiB"),
				new Unit("gibibyte", "GiB"),
				new Unit("tebibyte", "TiB"),
				new Unit("pebibyte", "PiB")
			});
		}

		public string GenerateHumanReadableString(long bytes, Base baseUnit = Base.Base10, bool longName = false)
		{
			NumberFormatInfo nfi = GetNumberFormatInfo();

			decimal decimalSize = bytes;
			int loop = 0;

			while (decimalSize >= (int)baseUnit && _baseUnits[baseUnit].Length - 1 > loop)
			{
				decimalSize /= (int)baseUnit;
				loop++;
			}

			string format;

			if (loop >= DecimalsAfterPower)
			{
				format = $"#,0.{new string('0', DecimalPoints)}";
			}
			else
			{
				format = "#,0";
			}

			var unit = longName ? _baseUnits[baseUnit][loop].LongName : _baseUnits[baseUnit][loop].ShortName;

			string formatedNumber = decimalSize.ToString(format, nfi);

			return $"{formatedNumber} {unit}";
		}

		private NumberFormatInfo GetNumberFormatInfo()
		{
			NumberFormatInfo nfi = new NumberFormatInfo();
			nfi.NumberDecimalSeparator =
				DecimalSeparator ?? CultureInfo.CurrentCulture.NumberFormat.NumberDecimalSeparator;
			nfi.NumberGroupSeparator =
				ThousandSeparator ?? CultureInfo.CurrentCulture.NumberFormat.NumberGroupSeparator;

			return nfi;
		}

		public enum Base
		{
			Base10 = 1000,
			Base2 = 1024
		}

		private readonly struct Unit
		{
			public Unit(string longName, string shortName)
			{
				this.LongName = longName;
				this.ShortName = shortName;
			}

			public readonly string LongName;
			public readonly string ShortName;
		}
	}
}