The kinetic stability of SDS foam was probed using Bartsch method at concentrations above CMC (0.03M and 0.06M) and below CMC (0.006M). The foam created from the higher concentration (0.06M) of micellar solution was more kinetically stable than that produced from the 0.03M SDS solution and showed a stepwise decrease. On the other hand, the foam produced from SDS surfactant concentration below CMC (0.006M) did not show such a behaviour and the height remained more or less constant. The effect of the foam lamella size on the bulk foam stability was also investigated. It was found that the critical lamella area is independent of the hydrostatic pressure. And, it took longer to reach the critical lamella area in the 0.06M SDS system than to reach the critical lamella area in the 0.03M SDS system. We probed the foam stability by studying the stability of a single foam lamella and observed the micellar layering phenomenon. We found 5 film thickness transitions in the case of 0.06M SDS system and 3 thickness transitions for 0.03M SDS system. Therefore, the foam lamella formed from the 0.06M SDS solution is kinetically more stable than that formed from the 0.03M SDS solution because the better layering structure in the former case slows down the liquid film drainage. Therefore, this study clearly demonstrates that both the size of the foam lamella and the micellar concentration are important factors in controlling the bulk foam stability.