cost fundamentals - variable cost, fixed cost and semi veriable cost

Variable cost : These are the costs which tend to vary directly with volume of output. These are also known as direct costs. These costs vary in total but remain fixed per unit.
Examples : a) Direct materials;
b) Direct labour;
c) Direct Expenses;
d) Variable overheads such as consumable stores, fuel etc.
Fixed Cost : It refers to the cost which tends to remain unaffected by variations in volume of output. This cost remains fixed during a given period and within a given range of activity. So, fixed cost is known as period cost. This cost remains fixed in total, but varies per unit.
Examples : a) Rent and rates of factory building;
b) Salary of works manager, General Manager or Sales manager;
c) Depriciation of buildings,
d) Insurance;
e) Interest on capital (if included in costs)
Semi-variable cost - Those are the costs which are partly fixed and partly variable. Both fixed and variable elements are present in semi-variable cost. This is also known as semi-fixed cost.
Examples :
a) Normal maintenance of building and plant;
b) Salary of supervisors;
c) Depreciation of plant and machinery;
d) Service department wages etc.