Every inch of batt insulation is equal to R-3, unless it’s more than 20 years old. For example, if you can see the floor joist (typically 2×6’s), that equals to R-18. For blown-in cellulose it is R -. Be sure to pay attention to the floor duct work. Lift the duct work to see if installers actually blew insulation underneath the ducts. Most commonly you will see insulation on vertical walls or the tray ceilings that have completely fallen down or never were installed properly.