Market sizing is one of the most common exercises in consulting case interviews, and in real projects too. When the market is in Africa, many candidates freeze: they do not know the orders of magnitude, or they quote figures without a year or a source. This post shows a simple method with real World Bank figures, and shares a clean dataset of 13 key indicators for all 54 African countries that you can reuse.

The dataset

The dataset gives, for each African country, the latest World Bank value of 13 indicators (growth, inflation, GDP, GDP per capita in current and PPP dollars, population, life expectancy, access to electricity, internet use, drinking water, forest area, unemployment and poverty), each with its year and its World Bank code. Country names are in English and French. It is a snapshot of 14 November 2026, under CC BY 4.0.

import pandas as pd df = pd.read_csv("hf://datasets/omaribanbdillah/africa-54-countries-key-figures/africa-54-countries-key-figures-wide.csv") df[["country_en", "population", "internet", "internet_year", "gdpPerCapita"]].head()

A worked example: how many people could use a mobile service?

Say a client wants to launch a paid mobile learning service in West and East Africa, and asks how many potential users each country has. A first, top-down estimate takes three steps.

1. Start from the population. Senegal had about 18.9 million people in 2025, Côte d'Ivoire 32.7 million, Kenya 57.5 million and Nigeria 237.5 million.

2. Keep only the people who use the internet. The share of internet users was 60.1% in Senegal, 41.4% in Côte d'Ivoire, 35.0% in Kenya and 41.2% in Nigeria (2024 values). This gives about 11.4 million internet users in Senegal, 13.6 million in Côte d'Ivoire, 20.1 million in Kenya and 97.9 million in Nigeria.

Note that the population is a 2025 figure and the internet share a 2024 figure. That is normal with public data, but say it out loud in an interview: "I am combining the 2025 population with the 2024 internet share, so this is an order of magnitude."

3. Narrow down to people who can pay. Here the choice of measure matters. GDP per capita in current US dollars was about 1,224 dollars in Nigeria and 3,050 dollars in Côte d'Ivoire in 2025. In purchasing power parity (PPP), the order flips: about 9,532 international dollars in Nigeria against 8,209 in Côte d'Ivoire. Current dollars tell you what a price in dollars means for a household. PPP tells you what people can buy at local prices. For a service priced in local currency, PPP is often the better guide. For a service priced in dollars, look at current dollars.

From there, you apply assumptions that you state clearly: the share of the target age group, the share that would pay, the price. The data gives you a solid base. Your judgment does the rest.

Sanity checks that impress interviewers

  • Access to electricity. A phone needs to be charged. Access to electricity was 82.9% in Senegal and 62.5% in Nigeria in 2024, but as low as 5.4% in South Sudan and 13.4% in Chad. A service that assumes daily use will not reach the same share everywhere.
  • Totals. The 54 countries have about 1.5 billion people. If your country estimate is a large share of that, check your logic.
  • Year and source. Always say where a number comes from and how old it is. "About 11 million internet users in Senegal, from World Bank data for 2024 and 2025" sounds far more credible than a bare number.
  • Modeled figures. Unemployment in this table is a modeled estimate by the International Labour Organization, not a survey count. Use it for orders of magnitude, not for precise comparisons.

Common mistakes

  1. Mixing current dollars and PPP dollars in the same calculation.
  2. Using a figure without its year, when some values are two or three years older than others.
  3. Treating a regional average as if it applied to every country. Africa has 54 very different economies: South Africa's GDP was about 427 billion dollars in 2025, that of the Comoros about 1.8 billion.

Practice

The best way to get comfortable is to repeat the exercise with different countries and products until the method becomes automatic. Pick a country, write down three figures with their year, and build a quick estimate in under five minutes.

Disclosure: I am the founder of Invea, the company behind Consulting 360, a mobile app to prepare consulting case and fit interviews, with sourced profiles of the 54 African countries. It is free to download on iPhone (App Store) and Android (Google Play): https://consulting360.app/. The dataset above comes from the same country data, and it is free to reuse with credit.

Data: World Bank, World Development Indicators, CC BY 4.0.