Current market price, limit price, and short term volatility define the probability that the market price will reach the desired limit price and that the order will be executed. A computer implemented method estimates the probability of executing the limit price order and provides output to the investor to assist in setting the limit price in an informed way. According to an embodiment of the present invention, a computer implemented system provides the investor with prices predicted to be executable at a set of given probabilities of execution. In one embodiment, the output to the investor includes a set of limit order execution probabilities, such as 80%, 90%, 95%, or similar, and corresponding limit order set prices. In another embodiment, an investor sets the execution probability, such as 95%, which is provided as input into the system. The output to the investor includes the calculated limit price corresponding to the set execution probability.