Since we are into trading and we watch out for the movement of the coins that we have in our bags it would help traders to see how much they already gained or loss just by looking at their tracker. One app that I usually see that traders download to their smart phone is Blockfollio because there you input the price of the coin by the time you bought it and you will easily see the % if you gained profits or not.

Others just use a simple journal that they can bring anywhere, they write down the price of the coins by the time they bought it and compare to the current price, old school you may say but it still works and practiced by a lot of traders.