The way total output changes due to change in all inputs in same proportion is known as law of

The law of returns to scale describes how total output changes when all factors of production (inputs) are increased or decreased in the same proportion [1]. This is a long-run production concept because all inputs are variable. There are three distinct stages: Increasing Returns to Scale (IRS), where output increases by a larger proportion than inputs; Constant Returns to Scale (CRS), where output increases by the exact same proportion; and Decreasing Returns to Scale (DRS), where output increases by a smaller proportion [2]. In contrast, the law of diminishing returns (or variable proportions) is a short-run concept that occurs when only one input is varied while others remain fixed. Therefore, the specific phenomenon of changing all inputs proportionally is uniquely defined as the law of returns to scale [1].

Sources

1. [1] Microeconomics (NCERT class XII 2025 ed.) > Chapter 3: Production and Costs > 3.6 RETURNS TO SCALE > p. 42
2. [2] Microeconomics (NCERT class XII 2025 ed.) > Chapter 3: Production and Costs > 3.6 RETURNS TO SCALE > p. 43