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Rate of natural increase

Rate of natural increase is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Rate of natural increase rather than just read about it. In short: In demography and population dynamics, the rate of natural increase (RNI), also known as natural population change, is defined as the birth rate minus the death rate of a particular population, over a particular time period. It is typically expressed either as a number per 1,000 individuals in the population or as a percentage.

Rate of natural increase — main illustration
Rate of natural increase — illustration

Key takeaways

  • Rate of natural increase belongs to science; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect Rate of natural increase to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Rate of natural increase from memory before moving on to harder problems.

Reference excerpt

In demography and population dynamics, the rate of natural increase (RNI), also known as natural population change, is defined as the birth rate minus the death rate of a particular population, over a particular time period. It is typically expressed either as a number per 1,000 individuals in the population or as a percentage. RNI can be either positive or negative. It contrasts to total population change by ignoring net migration. This RNI gives demographers an insight into how a region's population is evolving, and these analyses can inform government attempts to shape RNI.

Examples Suppose a population of 5,000 individuals experiences 1,150 live births and 900 deaths over the course of one year. To show the RNI over that year as a percentage, the equation would be (1,150 – 900) ÷ 5,000 = 0.05 = +5% To show the RNI as a number per 1,000 individuals in the population, the equation would be (1,150 – 900) ÷ (5,000/1,000) = 250 ÷ 5 = +50 It can also be shown as natural births per 1,000 minus deaths per 1,000 (1,150 ÷ 5) – (900 ÷ 5) = 230 – 180 = +50 To convert the RNI per 1,000 population to a percentage, divide it by 1,000. The equation would be +50 ÷ 1,000 = 0.05 = +5%

Uses The rate of natural increase gives demographers an idea of how a region's population is shifting over time. RNI excludes in-migration and out-migration, giving an indication of population growth based only on births and deaths. Comparing natural population change with total population change shows which is dominate for a particular region. Looking at this difference across regions reveals those that are changing mainly due to births exceeding deaths and those changing mainly due to migration. The map shows just such an analysis for the US.

The trend of RNI over time can indicate what stage of the Demographic Transition Model (DTM) a region or country is in.

National efforts to affect RNI Government attempts to shape the RNI of a region or country are common around the world. Policies can either encourage or discourage an increase in birth rates. For example, during the COVID-19 crisis Singapore offered families a “pandemic baby bonus” to encourage a higher birth rate, therefore increasing RNI. The US has considered similar policies. Another example was China's one-child policy, intended to decrease birth rates, therefore decreasing the RNI. A country with a good infrastructure to support families, women's health, and maternal/child health would likely have lower death rates from infant or maternal mortality, which would increase RNI.

See also List of countries by rate of natural increaseBirth rateMortality ratePopulation growth

References

Illustrations

Rate of natural increase: Natural annual increase in population per 1,000 people, from the CIA World Factbook, 2025. .mw-parser-output .legend{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .legend-color{display:inline-block;min-width:1.25em;height:1.25em;line-height:1.25;margin:1px 0;text-align:center;border:1px solid black;background-color:transparent;color:black}.mw-parser-output .legend-text{}  35 and up   30 to 34.9   25 to 29.9   20 to 24.9   15 to 19.9   10 to 14.9   5 to 9.9   0 to 4.9   -5 to -0.1   -10 to -5.1   -11.4 (Ukraine)   No data
Natural annual increase in population per 1,000 people, from the CIA World Factbook, 2025. .mw-parser-output .legend{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .legend-color{display:inline-block;min-width:1.25em;height:1.25em;line-height:1.25;margin:1px 0;text-align:center;border:1px solid black;background-color:transparent;color:black}.mw-parser-output .legend-text{}  35 and up   30 to 34.9   25 to 29.9   20 to 24.9   15 to 19.9   10 to 14.9   5 to 9.9   0 to 4.9   -5 to -0.1   -10 to -5.1   -11.4 (Ukraine)   No data
Rate of natural increase: Most Influential Component of Change for US Counties That Gained Population Between 2014 and 2015
Most Influential Component of Change for US Counties That Gained Population Between 2014 and 2015

Worked examples

Example 1 — a first encounter with Rate of natural increase

Start with the simplest possible case. Write down what Rate of natural increase claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Rate of natural increase before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Rate of natural increase ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Rate of natural increase

In research
Rate of natural increase appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses Rate of natural increase in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
Rate of natural increase is common in secondary-school and first-year university syllabi. It links to neighbouring topics Demographics indicators, Temporal rates, so understanding it makes those chapters shorter.
In everyday life
Look for Rate of natural increase outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.
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How to study Rate of natural increase in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Rate of natural increase means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain Rate of natural increase out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Rate of natural increase in simple terms?

In demography and population dynamics, the rate of natural increase (RNI), also known as natural population change, is defined as the birth rate minus the death rate of a particular population, over a particular time period. It is typically expressed either as a number per 1,000 individuals in the…

Why does Rate of natural increase matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Rate of natural increase?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Rate of natural increase.

Tags

  • Demographics indicators
  • Temporal rates

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