Most people think of income as binary. Either spend it or save it. In economics, this behavior is measured by consumption trends. This is simply the percentage of gross income that a household spends directly on goods and services instead of putting them into a savings account.
It’s not just about personal budget. This is the basic system of national income. Since money has two purposes: consumption and saving, the propensity to consume and the propensity to save always add up. If you don’t spend, you keep it.
Average and limited spending
Economists classify this concept into two different indicators. The first is the average propensity to consume. This is the ratio of total consumption to total income. By answering the question, “What percentage of my income do I actually spend?”
Another indicator is often more important for understanding macroeconomic trends: marginal propensity to consume. This measures how much your increase in income. If you get a $100 raise, how much of that extra $100 is saved rather than spent?
Why is this distinction important? Because the average propensity to consume varies according to the level of wealth.
Income differences in consumption habits
The average propensity to consume of low-income households is usually higher than that of high-income households. This is not a moral failure. This is a mathematical necessity.
Households in the lowest income brackets tend to have ratios above 1. They are forced to save or borrow money just to buy food, pay rent, and buy basic necessities. Their income is completely absorbed by the cost of living.
High-income households do not spend part of their income on the same needs. They have the opportunity to save considerable sums. Their average propensity to consume is clearly below 1.
“Therefore, the average propensity to consume of low-income households can be greater than 1, while the average propensity to consume of high-income households is only a fraction of 1.”
Why does the marginal propensity drive the economy?
For many economists, marginal propensity to consume is a more important concept. It has a synergistic effect.
Money does not disappear when governments increase spending or companies increase investment. It spins. The initial cash injection may lead to additional costs depending on how likely people are to spend their new income without saving.
A higher propensity to consume means that every dollar fed into the economy produces more gross national income. A low propensity to consume means that money stays in savings and economic growth slows down.
Compromise
There is no perfect balance here. High consumption stimulates short-term growth. High savings rates offer long-term investment capital. The tension between the two determines the business cycle.
Understanding where you fall on this spectrum can help explain why policy changes affect different demographics differently. Tax cuts for low-income earners tend to result in immediate spending because they have a higher propensity to consume. Tax cuts for the rich can result in less money flowing through the economy.
The mechanism is simple. The implications are complex. How much of your next paycheck can you really keep? The answer doesn’t just affect your bank account. It shapes the wider economy.
