Quantitative phase imaging (QPI) has been investigated to retrieve optical phase information of an object and applied to biological microscopy and related medical studies. In recent examples, differential phase contrast (DPC) microscopy can recover phase image of thin sample under multi‐axis intensity measurements in wide‐field scheme. Unlike conventional DPC, based on theoretical approach under partially coherent condition, we propose a new method to achieve isotropic differential phase contrast (iDPC) with high accuracy and stability for phase recovery in simple and high‐speed fashion. The iDPC is simply implemented with a partially coherent microscopy and a programmable thin‐film transistor (TFT) shield to digitally modulate structured illumination patterns for QPI. In this article, simulation results show consistency of our theoretical approach for iDPC under partial coherence. In addition, we further demonstrate experiments of quantitative phase images of a standard micro‐lens array, as well as label‐free live human cell samples. The left‐hand side panel shows individual phase contrast images in isotropic differential phase contrast (iDPC) dataset with corresponding gradient amplitude mask on top‐right side. White arrows denote phase gradient direction of each phase contrast image. The figure in right‐hand side is quantitative phase image of alive human adipose‐derived stem cells reconstructed using iDPC dataset.