What is inflation? Inflation is a sustained increase in the overall price level of goods and services in an economy over time. It is usually expressed as a percentage change in a price index over a period such as 12 months. When prices rise faster than a person’s income, their money buys less than before. Inflation is not the same as one shop raising the price of one item: the idea concerns a broad measure of prices across the economy.
The most important practical point is that lower inflation does not normally mean prices have returned to their old levels. It means the broad price level is increasing more slowly. If a representative shopping basket cost $100, then $105 one year later, the inflation rate for that period would be 5%. If its price rose again to $107.10 the following year, that next year’s rate would be 2%, even though the basket remained more expensive than two years earlier.
Quick notes: Inflation = rising overall price level. CPI = consumer price index, one common way to measure it. Disinflation = inflation slowing while prices may still rise. Deflation = falling overall price level. Purchasing power = how much your money can buy. Inflation has multiple possible causes, including stronger demand, supply disruptions, increased production costs and expectations. Different households experience price changes differently.
The definition of inflation: prices versus the inflation rate
Think of the price level as a measure of what a representative collection of goods and services costs at a particular time. The inflation rate tells us how fast that price level changes between two dates. These two concepts are related but not interchangeable. Prices can remain high even when the inflation rate falls dramatically.
An isolated price increase is not enough to establish economy-wide inflation. Suppose a concert ticket rises by 50%, while most household expenses stay the same. That is a major price increase for concertgoers, but by itself it does not tell us the inflation rate. A meaningful inflation measure considers a broad set of prices and the importance of different items in household expenditure.
The International Monetary Fund explains inflation as a rate of price increase over a period. Statistical authorities use carefully designed measures, often including a consumer price index. The outcome is an estimate based on the index’s population, coverage and methods—not a universal measurement of every person’s shopping list.
How inflation is calculated
A common calculation uses a consumer price index (CPI). If the CPI was 120 a year ago and is now 126, the annual inflation rate is (126 − 120) ÷ 120 × 100 = 5%. The numbers are index points, not dollars. The result describes the change in that index between the specified dates.
Inflation rate (%) = ((Price index now / Price index before) - 1) × 100
Example: Index 120 → 126
((126 / 120) - 1) × 100 = 5%For a single year, this is straightforward. Across several years, price increases compound. You cannot generally add rates from different years and expect an exact multi-year total. The correct method multiplies the year-by-year growth factors.
A worked example: why lower inflation can still feel expensive
- Start: a fictional basket costs $100.
- Year one: 5% inflation raises the basket to $105.
- Year two: 2% inflation raises the basket to $107.10.
- Compare: annual inflation has slowed from 5% to 2%, but prices are now 7.1% higher than at the start.
- Interpret: families may still struggle because the level of prices remains elevated even as the speed of increases falls.
This is the difference between a rate and a level. It is also why newspaper headlines about inflation easing can appear inconsistent with what people see at the supermarket. Both statements can be true: the rate of increase has eased, and the price is still above its earlier level.
What causes inflation? Four useful mechanisms
1. Demand-pull inflation
Demand-pull pressures arise when spending on goods and services grows faster than an economy can easily supply them. Businesses may face more orders than they can fulfil at existing prices. Competition for labour, equipment and products can contribute to higher prices. A simple illustration is a popular event with limited seating: demand can push prices up, although an event’s ticket price is not itself a national inflation rate.
An expanding economy does not automatically create harmful inflation. The effect depends on production capacity, productivity, competition, supply conditions and how quickly businesses can respond.
2. Cost-push inflation
Cost pressures arise when producing or transporting goods and services becomes more expensive. Examples include a sudden rise in energy prices, expensive imported materials, disrupted supply chains or higher costs of essential inputs. Some firms absorb part of the increase in profit margins; others pass part of it on to customers. Different sectors respond differently.
For an import-dependent economy, changes in foreign prices and exchange rates can affect domestic costs. This is one reason international developments can influence household bills even when local demand is not exceptionally strong.
3. Money, credit and economic policy
Monetary and financial conditions can influence demand, borrowing, saving and the long-run value of money. Over long periods, persistently excessive growth in money relative to an economy’s productive capacity can contribute to high inflation. However, it is misleading to claim that every monthly increase in consumer prices has one simple cause.
Policy transmission is not immediate. Interest rates, credit conditions, exchange rates, expectations and changes in real output interact. A careful economic explanation distinguishes short-run shocks from persistent underlying inflation.
4. Expectations and repeated adjustments
If employees, businesses and households expect prices to keep rising rapidly, they may adjust wage demands, contracts and selling prices. Some future price changes may then reflect expectations formed earlier. Expectations do not act alone, but they can make inflation harder to reduce once it becomes persistent.
What is the Consumer Price Index?
A consumer price index tracks the prices of a representative collection of goods and services purchased by the population covered by the index. The basket often includes categories such as food, housing, transport, healthcare, education, clothing and recreation. Statistical authorities estimate how prices change and combine the observations using specified weights.
The weights matter. If housing uses a large share of the expenditure measured by an index, housing prices can have more influence than a small category. A product that becomes dramatically more expensive may matter greatly to one family but have a more limited effect on the overall index if it is not a large part of total expenditure.
Consumer price indices also involve difficult methodological decisions: which households are included, how prices are collected, how quality changes are handled, and when expenditure weights are updated. These details are not footnotes to avoid. They determine what a published number means.
Why your household inflation may differ from the official figure
- Different spending patterns: a family with young children may spend more on childcare than a retired household.
- Different housing situations: homeowners, tenants and households in different areas face different costs.
- Different transport choices: car owners and public-transport users respond differently to fuel and vehicle costs.
- Substitution: households may switch products or shops as prices change.
- Frequency: frequently purchased groceries can dominate what people notice, even if less frequent categories also matter in the index.
- Different incomes: a particular price increase can be more difficult for a lower-income household even when the measured percentage change is similar.
The official measure is useful because it applies a consistent methodology to a defined population. Your household budget is useful because it describes the money you actually spend. Neither replaces the other. A complete explanation uses both appropriately.
Inflation, disinflation and deflation: the three-way distinction
Inflation
The broad price index rises over the period. A rate of 6% means the index increased 6% over the stated interval, under that particular method.
Disinflation
The price index keeps rising, but at a slower rate. If inflation moves from 6% to 3%, this is disinflation. A family does not receive an automatic refund of the previous price increases.
Deflation
The broad price index falls over the period. An annual inflation rate of −1% indicates a 1% decline in the index over that year. Deflation is not always a simple benefit: widespread, persistent declines can interact with debts, wages, employment and consumer or business decisions.
Individual goods can fall in price during a period of general inflation. Technology products, for example, may become cheaper while other categories rise. It is the overall movement of the specified index that determines the inflation measure.
What is hyperinflation?
Hyperinflation refers to exceptionally rapid and often destabilising increases in prices. Definitions differ in academic and historical discussions; some commonly cited classifications use a monthly threshold rather than a yearly one. The everyday lesson is that ordinary moderate inflation and a collapse of monetary stability are not equivalent situations.
During extreme inflation, prices may change quickly, wages lose value before they can be spent, and people may struggle to use the local currency for routine planning. Such episodes can reflect deep economic, financial and political problems. They should not be invoked casually simply because household costs have risen.
How inflation affects income and purchasing power
A salary increase can look positive in cash terms while leaving a worker worse off in purchasing-power terms. Economists often distinguish nominal amounts (measured in current money) from real amounts (adjusted for price changes). The real comparison helps answer how much the income can buy.
Suppose a person’s monthly pay rises from $3,000 to $3,120, a 4% increase, while the relevant price index rises by 5%. The approximate change in real pay is 1.04 ÷ 1.05 − 1 = −0.95%. The pay packet contains more dollars, but those dollars purchase slightly less of the representative basket than before.
A household with fixed income can be particularly exposed when its major expenses rise. Others may experience wage growth that exceeds inflation. The impact is uneven: the words ‘inflation hurts everyone equally’ are not accurate.
Inflation and savings
A savings account may pay interest while inflation reduces purchasing power. The relevant comparison is the interest earned after relevant costs and taxes, where applicable, against the rate of price increase during the same period. A positive nominal interest rate does not necessarily mean a positive real return.
If savings earn 2% while a matching price index rises 4%, the approximate real change is negative. The exact real rate is (1.02 ÷ 1.04 − 1) × 100 ≈ −1.92%. This is a mathematical example, not a recommendation to choose a particular investment or financial product.
Inflation and borrowing
Unexpected inflation can change the real value of debt repayments. Borrowers who agreed to fixed nominal repayments may, under some circumstances, repay with money that buys less than expected; creditors can lose purchasing power. But this does not mean inflation is always good for borrowers. Interest rates, refinancing costs, wages, loan terms and financial stability can move against them.
Floating-rate borrowing can become more expensive when policy and market rates rise. A household should not rely on simplistic claims such as ‘inflation wipes out debt’. Real outcomes depend on the contract, income path, changes in interest rates and the broader economy.
How central banks try to control inflation
Central banks influence monetary and financial conditions to help maintain price stability alongside other legal mandates. Many central banks use an interest-rate policy framework: higher policy rates can dampen some spending and borrowing over time, while lower rates can support demand. The effect is not instantaneous or perfectly predictable.
Singapore is a valuable exception to the classroom assumption that every central bank primarily changes a domestic short-term policy interest rate. The Monetary Authority of Singapore uses an exchange-rate-centred monetary policy framework, reflecting the city-state’s open economy and imported-price exposure. A strengthening Singapore dollar can help moderate imported inflation, although it cannot eliminate every domestic cost pressure.
Different countries publish different targets, measures and policy decisions. To understand a particular country, consult its central bank and statistical authority rather than applying one country’s rules everywhere.
What is core inflation?
Core inflation is an attempt to examine underlying price pressures by excluding or reducing the influence of selected categories or unusually volatile prices. The exclusions are not universal. In some countries, a familiar core measure excludes food and energy; other measures use different rules.
In Singapore, MAS Core Inflation excludes accommodation and private road transport costs from CPI-All Items inflation. That is a specific national definition. It should not be re-described as merely ‘inflation without food and energy’. The headline measure and the core measure answer different questions and both can be useful.
For the current definition and Singapore’s monetary-policy reasoning, see the MAS monetary policy statement at a glance, October 2026. For a global introduction, see the IMF’s explanation of inflation.
Inflation in Singapore: a reader’s practical guide
When reading a Singapore inflation report, begin by identifying whether it discusses CPI-All Items or MAS Core Inflation. Check the period: month-on-month, year-on-year and calendar-year averages are different measurements. Also note whether a figure is an observed statistic, an official forecast or a journalist’s interpretation.
- Find the source: use the Singapore Department of Statistics and MAS for official data and definitions.
- Identify the index: headline CPI-All Items or MAS Core Inflation.
- Identify the period: compare like with like—annual change, monthly change or average for a specified year.
- Examine the categories: understand which prices contributed most to the reported movement.
- Compare with your budget: note your own major expenses without assuming they mirror the index.
- Do not overinterpret one month: temporary shocks, seasonal influences and base effects can distort the impression from a single number.
The latest figures change with official releases. This article teaches interpretation rather than embedding a quickly outdated ‘today’s inflation rate’. Current official data and policy should be checked at SingStat and MAS.
What is the difference between inflation and the cost of living?
Inflation is a rate of change in a broad price measure. The cost of living concerns the money required to achieve a particular standard of living, taking into account household needs and circumstances. A household may find life expensive because of housing, healthcare or childcare even when the annual inflation rate is low.
You cannot fully describe affordability from the CPI alone. Income, taxes, housing arrangements, family size, available services, subsidies and consumption choices matter too. For a Singapore household-focused treatment, see Cost of Living in Singapore: Household Budgets and Financial Help.
What is the difference between inflation and GDP growth?
GDP growth describes changes in economic production or output; inflation describes price changes. A country can have economic growth and inflation at the same time. Economic growth may be reported in nominal terms or in real, price-adjusted terms. A headline ‘the economy grew 5%’ is incomplete until we know which measure it uses.
A GDP price deflator is another measure of prices, covering a different collection of economic production than a consumer price index. It should not be mistaken for a household cost-of-living index. The distinction matters when comparing public economic statistics.
Why businesses and families both watch inflation
Businesses consider how costs and customer demand influence prices, wages, contracts and investment. A firm facing higher input costs cannot assume it can raise its prices without reducing sales. A family considers income, essential bills, savings and long-term commitments. Inflation changes the information both groups use to make decisions.
A practical household exercise is to list the recurring monthly expenses that matter most, then separate changes in quantity from changes in unit price. A higher electricity bill may reflect higher tariffs, higher usage or both. Accurate interpretation starts by checking the components instead of assigning every change to inflation.
How to read an inflation news headline correctly
- Look for the country: different economies have different price indices and economic conditions.
- Look for the metric: headline CPI, core inflation, producer prices or another index.
- Look for the time period: year-on-year and month-on-month figures are not substitutes.
- Look for the previous base: a high or low comparison month can alter the reported annual rate.
- Separate actuals from forecasts: a forecast is not a measured outcome.
- Ask about prices: does the story mean prices are falling or merely rising more slowly?
- Ask about households: which spending categories are most relevant to the people affected?
For example, ‘Inflation dropped to 2%’ usually does not mean supermarket prices fell by 2%. It may mean the selected index increased 2% compared with the stated earlier period, which is lower than the previous reported rate. The full report clarifies the comparison.
Five misleading claims about inflation
- ‘Inflation fell, so everything is cheaper.’ Disinflation can leave prices higher than before.
- ‘One very expensive item proves the national inflation rate.’ CPI uses a broader basket and weights.
- ‘A pay rise always improves living standards.’ Compare income growth with relevant price changes.
- ‘Core inflation means food and energy are always excluded.’ Definitions differ across countries; Singapore’s MAS core measure has different exclusions.
- ‘A higher interest rate immediately fixes inflation.’ Transmission takes time and the effect depends on the underlying causes.
A seven-day plan for learning inflation
- Day 1: Define inflation and distinguish a price level from a change in that level.
- Day 2: Calculate one year of inflation from a fictional CPI.
- Day 3: Calculate two consecutive years and explain why rates compound.
- Day 4: Compare demand, cost, money conditions and expectations using separate scenarios.
- Day 5: Compare nominal pay with inflation-adjusted purchasing power.
- Day 6: Read an official local inflation report and label its measure and time period.
- Day 7: Explain why inflation may slow while households still report high costs.
The learner should be able to work with a new set of values, not only repeat the example from this page. Understanding inflation is a combination of accurate definitions, arithmetic and economic judgment.
Frequently asked questions about inflation
What is inflation in simple words?
Inflation means the overall level of prices is increasing over time, so a unit of money generally buys less of the representative basket than before.
Is inflation always bad?
High, unpredictable inflation can be especially harmful, but the consequences of inflation depend on its size, stability, economic conditions and how incomes and contracts adjust. Many policy frameworks aim for low, stable inflation rather than permanently falling prices.
What is CPI?
CPI stands for consumer price index. It tracks changes in the prices of a representative basket of goods and services for a defined population.
What is inflation versus deflation?
Inflation is a rise in the overall price index; deflation is a decline in that index over the stated period.
What is disinflation?
It means the inflation rate is slowing. Prices can keep increasing, just not as quickly as they did before.
Why do groceries feel more expensive than official inflation?
A particular household’s spending basket may differ from the index, and frequently purchased items are more noticeable. Check category data and your actual receipts rather than assuming one of the measures must be false.
How do interest rates affect inflation?
Interest rates can influence borrowing, spending, saving and demand over time. Their effects vary with circumstances and central-bank frameworks.
What is MAS Core Inflation?
It is Singapore’s core measure of consumer-price inflation that excludes accommodation and private road transport costs from CPI-All Items.
Where can I find the latest inflation rate?
Check the national statistical authority and central bank for your country. For Singapore, begin with SingStat and MAS and confirm the date and index.
Continue learning with eduKateSG
For the step-by-step study version, read How to Learn Inflation Quickly and Correctly. For a wider household perspective, see Cost of Living in Singapore. For school economics, read Economics Reference: Unemployment, Inflation, CPI and Policy. Each article answers a distinct question.
Sources and date-sensitive cautions
The International Monetary Fund’s inflation explainer provides definitions, common causes and purchasing-power implications. The US Bureau of Labor Statistics CPI FAQ explains how a consumer price index is constructed and used. For Singapore’s distinctive framework, consult MAS’s October 2026 policy explanation. Numerical baskets and salary examples here are invented teaching calculations; they are not live inflation statistics, financial forecasts or personal investment advice.