The monitoring of plant development during the growing season is a fundamental base for site-specific crop management. In this regard, the amount of plant biomass at a specific phenological stage is an important parameter to evaluate the actual crop status. Since biomass is directly only determinable with destructive sampling, methods of recording other plant parameters, such as crop height or density, which are suitable for reliable estimations are increasingly researched. Over the past two decades the research interest has focused on non-destructive remote sensing approaches. They have the main benefit that plant parameters can be obtained without disturbing the plant growth. Terrestrial laser scanning (TLS) is known as promising tool for determining plant height at field scale and monitoring its development. In former studies, the usability of biomass regression models (BRMs) for estimating spring barley biomass based on TLS‑derived plant height across‑season was shown. However, from a field management perspective the in‑season estimation of the actual biomass is more important. The herein presented study investigates the accuracy of these proven models for estimating the actual crop biomass at a specific date during the growing season. Overall the validity of all BRMs for across-season analyses is supported by high R² values of up to 0.73 and 0.85 between measured and estimated values for fresh and dry biomass, respectively. The R² values for the campaign‑wise separated analyses are generally lower (ranging from 0.01 to 0.23). In contrast, strongly reduced root mean square error (RMSE) and relative RMSE values for these analyses underline the benefit of a campaign‑wise separated investigation. In conclusion, the results verify that TLS‑derived plant height is a suitable estimator for crop biomass at a specific date.