Basic loss per share excludes dilution and is computed by dividing loss available to common shareholders by the weighted-average number of shares outstanding for the period. Diluted loss per share reflects the potential dilution that could occur if securities or other contracts to issue common stock were exercised or converted into common stock, except for periods when the Company reports a net loss because the inclusion of such items would be antidilutive. The antidilutive effect of 623,276 shares and 179,490 shares from stock options were excluded from diluted shares for the three months ended March 31, 2018 and 2017, respectively.

The following is a reconciliation of the amounts used in calculating basic and diluted net loss per common share: