I was working in cleaning 2 months ago into bakery was medium size but I heard the contrat was about $10,000 monthly who my boss keep it(sub-contrator) and we were working 2 persons in the month we together we did about $1,200 because we worked on night 4 hours every day.
Unable to answer due to total lack of details.What you would do is to make an est of the number of hours it will take to clean the factory. Then multiply the number of hours by your billing rate, and that is the est for your cleaning fee.