In Excel, you can try the following equation (in Row 4) to convert blows to foot to equivalent SPT N vlaues. Cell E4 will be SPT for SPT samples, U for a Dames & Moore sampler with 2.5" ID & 3.25" OD, and M for modified California samples with 1.94" ID & 2.5" OD. Cell D4 has the blows per foot...