I'm going away for 2 days and leaving my 2 month old son with grandma, he's exclusively breastfed…

I'm going away for 2 days and leaving my 2 month old son with grandma, he's exclusively breastfed and I've been trying to pump every day to make sure my mom doesn't run out of milk for him. Anyone know how many total ounces I should have for him? Hubby and I will really be gone for one day, but I'm rounding it up to 2 days, just in case.