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    VPD truth calculator

    Start with air temperature and RH. Add a measured leaf temperature, canopy placement, and current calibration evidence before Verdant will compare the result with a stage target.

    Nothing is uploaded or savedAir estimate first · verified leaf VPD for target status

    Calculate from a manual reading

    %

    Normal flower-room readings around 40–55% are valid here for an air-VPD estimate. Target status still requires the optional evidence below.

    °F

    Measure a representative leaf in the current light and airflow conditions.

    Measurement evidence

    These checks stay in this browser session and are not uploaded. Missing or old evidence keeps the result visible as an estimate but blocks a target-status claim.

    %

    Leave blank for an air estimate. Target status requires a documented 75–100% RH calibration reference, not the room setpoint.

    Stage comparison remains locked until the measurement evidence is verified.

    Manual inputs · calculated locally · not live telemetry. Nothing is uploaded or saved. Air-only results are labeled as estimates.

    Accuracy before color

    Air VPD describes the atmosphere. Leaf-to-air VPD adds the plant surface temperature. Neither proves plant health or justifies a sudden equipment, nutrient, or irrigation change. Verdant keeps the target color locked until the measurement basis is explicit and the calibration evidence is current.

    Want the reasoning behind source labels and stage context? Read the grow-room VPD tracking guide.

    VPD calculator questions