Systems and methods for optical fluid identification approximation and calibration are described herein. One example method includes populating a database with a calculated pseudo optical sensor (CPOS) response of a first optical tool to a first sample fluid. The CPOS response of the first optical tool may be based on a transmittance spectrum of a sample fluid and may comprise a complex calculation using selected components of the first optical tool. A first model may be generated based, at least in part, on the database. The first model may receive as an input an optical sensor response and output a predicted fluid property. A second model may also be generated based, at least in part, on the database. The second model may receive as an input at least one known/measured fluid/environmental property value and may output a predicted pseudo optical sensor response of the first optical tool.