Convert Kilogram (kg) to Attogram (ag) instantly.
About these units
Kilogram (kg)
The kilogram is the base unit of mass in the SI system and the only SI unit defined directly by a fundamental constant rather than a physical object. Originally, its definition was tied to a platinum–iridium artifact stored in France—the famous "International Prototype Kilogram." Over time, tiny mass changes in the prototype and its official copies created difficulties for high-precision science. In 2019, the kilogram was redefined using Planck's constant, linking mass to the laws of quantum physics through the Kibble balance. This innovation ensures universality, stability, and reproducibility across the world. The kilogram is central to commerce, science, engineering, and every quantitative field dealing with matter. Its decimal relationships with other metric units (grams, milligrams, tons) make it universally convenient. From groceries to spacecraft mass budgets, the kilogram anchors modern mass measurement.
Attogram (ag)
An attogram is 10⁻¹⁸ grams, an incredibly small mass used only in advanced scientific settings. At this scale, we are dealing with masses comparable to large molecules, viruses, or clusters of atoms. Modern techniques such as atomic force microscopy, mass spectrometry, and nanoscale resonators allow detection of attogram-level changes. Researchers studying chemical reactions, nanotechnology, and molecular biology may use attograms when describing ultra-fine mass differences. The attogram is an example of scientific progress: a unit unnecessary in the past, but now essential for understanding the smallest measurable interactions in nature.