Conversion of δ¹⁸O values between PDB and SMOW

To convert from delta values reported relative to one standard to another:

 

Example:

δ¹⁸O(VSMOW) = δ¹⁸O(VPDB) + δPDB-SMOW + δ¹⁸O(VPDB)*δPDB-SMOW/1000

δ¹⁸O(VSMOW) = δ¹⁸O(VPDB) + 30.92             + δ¹⁸O(VPDB)*30.92/1000

δ¹⁸O(VSMOW) = 30.92 + 1.03092 * δ¹⁸O(VPDB)

from Libby Stern at utexas site