Those clever folks at PC Magazine have devised an iPhone Death Watch for those of you who are worried about your new toy’s battery and are already fretting over its expiration date and possible withdrawal while you exchange it. Simply enter the date of purchase and the calculator will tell you when to plan for the end and its subsequent replacement.

Apple claims that after 400 charges, an iPhone retains only 80%. Since this was all the info the mag could get out of the company, they just used one of their own to estimate how long between charges, added in the length of trickle charging over a USB port, and came up with 1.5 days. They also stretched the amount of charges to 450, multiplied the two together, and voila, the Death Widget was born. If you get too paranoid about the countdown and take the issue too seriously, we suggest that you take off another couple of days to account for all that calendar reassurance.