Mechanical forces are critical for virtually all fundamental biological processes, yet quantification of mechanical forces at the molecular scale remains challenging. Here, we present a new strategy using calibrated coiled-coils as genetically encoded, compact, tunable, and modular mechano-sensors to substantially simplify force measurement , via diverse readouts (luminescence, fluorescence and analytical biochemistry) and instrumentation readily available in biology labs. We demonstrate the broad applicability and ease-of-use of these coiled-coil mechano-sensors by measuring forces during cytokinesis (formin Cdc12) and endocytosis (epsin Ent1) in yeast, force distributions in nematode axons (β-spectrin UNC-70), and forces transmitted to the nucleus (mini-nesprin-2G) and within focal adhesions (vinculin) in mammalian cells. We report discoveries in intracellular force transmission that have been elusive to existing tools.