The pre-money valuation is the value of your company that you and your investors agree upon just before you raise money in a priced equity round (e.g. a Series A raise). Pre-money valuation is not connected to the terms “Pre-money SAFE” and “Post-money SAFE”.
A pre-money valuation is connected to your “post-money valuation” which is the value of your company after you have raised your priced equity round. Your post-money valuation is your pre-money valuation plus the Series A Investment Amount you raised.
Your pre-money valuation is used to determine the price per share that your new investors will pay. The price per share is calculated by dividing your pre-money valuation by the sum of your existing cap table shares and options plus the shares you give to your SAFE investors plus the shares set aside for an option pool top up.