Layoff Using Reduced Work Week Hours of 32 hours or 40 hours?

Our company has been on a reduced work week at 32 hours / week for over a year now. We are now starting into Layoffs and doing calculations I am inquiring if I use 32 hours / week for their Termination Notice and for Severance pay. (The employment contracts have been revised via letters to each employee stating reducing to 32 hours). Thanks, I appreciate your speedy response back, Erin