hardness

Tablet hardness is the force needed to crush a tablet — a simple gauge of how mechanically strong it is. It answers a practical question: will this tablet survive coating, packaging, shipping and a rattling pill bottle without breaking, while still being able to fall apart once swallowed?

It is measured on a hardness tester, which holds the tablet between two jaws and slowly squeezes until it fractures, reporting the breaking force (often in newtons or kiloponds). Hardness depends on the compression force used on the press and on the formulation — more binder or higher pressure gives a harder tablet. Because larger tablets naturally take more force to break, the value is sometimes converted to a shape-independent tensile strength for fair comparison.

Hardness is a balancing act, not a target to maximise. Too soft and the tablet crumbles in handling; too hard and it may resist disintegration, slowing release of the drug. It is closely related to friability — both probe mechanical strength — but hardness is a single crushing force whereas friability measures resistance to repeated abrasion.