Dear ronald_peterson,
The calculation as needed by you can be easily done using a normal calculator... I mean, if it is just the % of buying / selling price (long / short), why need a special calculator ? I hope I got your needs correctly.
A stoploss calculator should take into account the noise created by intraday volatility (highs / lows) and calculate the stoploss accordingly (so that it is not hit by the volatility). This way, the only way your stoploss can get hit is by more-than-normal volatility or when the trend reverses (which is what we want). Please tell me if I am in sync with your requirement.
If this is what you want, please refer to my thread
http://www.traderji.com/introductions/7714-stop-loss.html wherein I have given my method of calculating stoploss. If you are using metastock, I can give you the formula (stoploss indicator).
Regards,
Abhay (AAD)