Calculator
Formula Used
Four-firm concentration ratio:
CR4 = S1 + S2 + S3 + S4
S1, S2, S3, and S4 are the market shares of the four largest firms.
When sales values are entered, each firm share is calculated first:
Firm Share = Firm Sales / Total Market Sales × 100
The calculator sorts all firms from highest share to lowest share. It then adds the first four shares. It also calculates HHI as the sum of squared market shares.
How to Use This Calculator
- Enter a market name and period.
- Select market share mode or sales value mode.
- Add firm names and their shares or sales values.
- Enter total market sales when using sales mode.
- Choose decimal places for rounded output.
- Press the calculate button to show the result.
- Use CSV or PDF buttons to save the report.
Example Data Table
| Firm | Market Share | Rank | CR4 Status |
|---|---|---|---|
| Firm A | 28% | 1 | Included |
| Firm B | 22% | 2 | Included |
| Firm C | 15% | 3 | Included |
| Firm D | 11% | 4 | Included |
| Firm E | 9% | 5 | Not Included |
Understanding the Four-Firm Concentration Ratio
A four-firm concentration ratio shows how much of a market is held by the four largest firms. It is often written as CR4. The measure is simple, but it gives useful first insight. A low value suggests a fragmented market. A high value suggests that a few firms may shape prices, output, or service levels.
Why This Calculator Helps
This calculator accepts market shares or sales values. You can enter each firm, rank the leaders, and compare the top four total against the rest of the market. When revenues are used, the tool converts every firm value into a percentage share before adding the four largest shares. This keeps the method consistent.
The result also includes HHI, active firm count, leader gap, and basic structure notes. These extra checks help users avoid reading CR4 alone. A market can have the same CR4 with very different internal patterns. One large leader and three small followers can feel different from four balanced leaders.
How to Read the Result
A CR4 below forty percent usually points to broad competition. A value from forty to sixty percent may suggest moderate concentration. A value above sixty percent deserves closer review, especially when the biggest firm has a strong lead. These labels are guides, not legal findings. Real competition review also considers entry barriers, buyer power, substitutes, geography, regulation, and product differences.
Good input quality matters. Use the same period for every company. Do not mix annual sales with quarterly sales. Do not combine local shares with national totals. If the listed firms do not cover the full market, enter total market sales in revenue mode. In share mode, make sure the combined share is realistic.
Practical Uses
Students can use the page to test market structure examples. Analysts can prepare quick tables for reports. Small businesses can compare competitors before entering a market. Policy readers can use it as a screening tool. The CSV and PDF buttons make the output easier to save. The example table also shows how a standard data set should look before calculation. Save each run, compare scenarios, and document assumptions for future reviews. This supports clearer team discussion later. Simple records reduce repeated work well.
FAQs
What is a four-firm concentration ratio?
It is the combined market share of the four largest firms in a market. It is often used as a quick measure of market concentration.
What does a high CR4 mean?
A high CR4 means the largest four firms control a large part of the market. It may suggest strong market power or limited competition.
Can I use sales instead of market share?
Yes. Select revenue mode, enter firm sales, and add total market sales. The calculator converts sales into shares before calculating CR4.
How many firms should I enter?
Enter all known firms when possible. The calculator ranks them and uses the largest four shares for the main CR4 result.
What is the HHI value?
HHI is the sum of squared market shares. It gives another view of concentration and helps compare markets with similar CR4 values.
Why is total market sales important?
Total market sales are needed in revenue mode. They let the calculator convert each firm value into a proper market share percentage.
Can CR4 exceed one hundred percent?
It should not exceed one hundred percent with correct share data. If it does, check inputs, units, or total market sales.
Is CR4 enough for legal analysis?
No. CR4 is a screening measure. Legal or regulatory review also needs entry barriers, substitutes, geography, buyer power, and conduct evidence.