It depends on whether the LPN school is properly accredited.
In my home state of California, LVN schools
only need to be state-approved by the Bureau of Postsecondary Education. LVN schools don't necessarily need to be accredited in California; however, many are.
If your LPN school is state-approved only
, the curriculum might not count for any credit hours whatsoever. Rather, the state-approval will only permit you to take NCLEX upon completion of the program. The disadvantage to state-approved schools is the possibility that RN bridge programs may want you to start from scratch.
If your LPN program is also accredited
, the curriculum will often count as one year's worth of credit hours (30 or so units). Most RN bridge programs will accept LPNs as advanced-placement students if they graduated from accredited LPN schools. Your home state may have differing rules.