Converting binary value from BitArray to an int and back in C#

What I am creating is essentially a binary clock face with touch input for setting values as well as displaying - so I need to convert both ways between an int and a binary sequence in a BitArray.

I cobbled this together (borrow and modifying a bit from a couple different examples I found):

public class BinaryConverter
    {
        public static BitArray ToBinary(int numeral)
        {
            BitArray binary = new BitArray(new int[] { numeral });
            bool[] bits = new bool[binary.Count];
            binary.CopyTo(bits, 0);
            return binary;
        }

        public static int ToNumeral(BitArray binary, int length)
        {
            int numeral = 0;
            for (int i = 0; i < length; i++)
            {
                if (binary[i])
                {
                    numeral = numeral | (((int)1) << (length - 1 - i));
                }
            }
            return numeral;
        }
    }

It isn't especially verbose, but in my head before I started it should have been a couple of lines per method, perhaps better leveraging some .NET classes like System.Convert (though, I can't quite see how to do that). Is there a cleaner way to do this? Do you have any other suggestions for improvement?

You've made it much more complicated than necessary.

The conversion to a BitArray needlessly copies the values to the bool array bits. You could instead use that on the conversion back to int.

public static class BinaryConverter
{
    public static BitArray ToBinary(this int numeral)
    {
        return new BitArray(new[] { numeral });
    }

    public static int ToNumeral(this BitArray binary)
    {
        if (binary == null)
            throw new ArgumentNullException("binary");
        if (binary.Length > 32)
            throw new ArgumentException("must be at most 32 bits long");

        var result = new int[1];
        binary.CopyTo(result, 0);
        return result[0];
    }
}

StackExchange Code Review Q#3796, answer score: 17