Market Share Calculations
Market share questions test your ability to work with percentages, totals and proportions. They appear in numerical reasoning tests for consulting, retail and FMCG roles. Here's how to handle them.
Basic Formula
Market share = (Company sales ÷ Total market sales) × 100
Or: Market share = (Company sales ÷ Market size) × 100
Market size (or total market) is the sum of all competitors' sales in that market.
Finding Market Size from Share
If you know one company's sales and its share:
Market size = Company sales ÷ (Share ÷ 100)
Example: Company A has £50m sales and 20% share. Market size = 50 ÷ 0.20 = £250m.
Finding Another Company's Sales
If you know market size and one company's share, you can find that company's sales:
Company sales = Market size × (Share ÷ 100)
If you know Company A's sales and share, and need Company B's sales: first find market size, then apply B's share.
Common Question Types
- "What is Company X's market share?" – X's sales ÷ Total market × 100.
- "What is the total market size?" – Use one company's sales and share to back-calculate.
- "If Company X grows 10% and the market stays flat, what is X's new share?" – New X sales = Old × 1.10. New share = New X ÷ (Total market) × 100. Total market unchanged.
- "Rank companies by market share" – Calculate share for each, then sort.
Pitfalls
- Units – Ensure all figures are in the same units (e.g. £m, units).
- Scope – "European market" vs "global market"—check what the total includes.
- Time period – All data for the same period (e.g. Q3 2024).
Practice with numerical reasoning questions and the numerical reasoning test.
Frequently Asked Questions
What if the table gives "share of revenue" vs "share of units"?
They can differ. A company can have high revenue share but lower unit share if it sells premium products. Use the measure the question asks for.
How do I calculate share when "Others" is given?
"Others" is often a single row. Add it to the named companies to get total market. Or subtract named companies from 100% if shares are given in %.
What if market size changes?
If the market grows, a company can have higher sales but lower share (if it grows slower than the market). Recalculate share with the new total.