Economical

1. Pertaining to the household; domestic.
2. Relating to domestic economy, or to the management of household affairs.
3. Managing with frugality; guarding against waste or unnecessary expense; careful and frugal in management and in expenditure; -- said of character or habits.
4. Managed with frugality; not marked with waste or extravagance; using the minimum of time or effort or resources required for effectiveness; frugal; -- said of acts; saving; as, an economical use of money or of time; an economic use of home heating oil.
5. of or pertaining to the national or regional economy; relating to political economy; relating to the means of living, or the resources and wealth of a country; relating to the production or consumption of goods and services of a nation or region; as, economic growth; economic purposes; economical truths; an economic downturn.
6. Regulative; relating to the adaptation of means to an end.
7. of or pertaining to economics.
8. profitable. Opposite of uneconomic.
9. avoiding waste; as, an economical meal. Opposite of wasteful.

Economical is the usual form when meaning frugal, saving; economic is the form commonly used when meaning pertaining to the management of a household, or of public affairs.