---
term: "Reduction of Area"
category: "material-testing"
shortDefinition: "Percent decrease in minimum cross-sectional area after tensile fracture relative to the original area; a ductility indicator reported alongside elongation at break."
formula: "Z = 100 × (A0 − Au) / A0"
relatedStandards: ["ISO 6892-1","ASTM E8"]
url: "https://vectorbtc.com.tr/resources/glossary/reduction-of-area/"
---

## What it measures

**Reduction of area (Z)** quantifies how much the fracture cross-section has **necked down** compared with the original specimen area. High Z generally indicates **ductile** fracture; very low Z can signal brittle failure modes.

## How it is tested

After a tensile test to fracture, measure the **minimum diameter or area** at the neck and compare with the original gauge section. Some workflows use post-fracture micrometer readings; others estimate from fracture appearance for screening only.

## Standards and reporting

ISO 6892-1 and ASTM E8 include Z for round and flat specimens when the fracture is suitable. Report specimen type and measurement method because irregular fractures bias area estimates.

## Common errors

Measuring away from the minimum neck, including shear lips inconsistently, and mixing engineering strain with area-based ductility metrics without context.