Average Poverty Gap Calculator
Poverty statistics usually count how many people are poor. This calculator measures how poor they are: the average income shortfall per poor person in currency, that shortfall as a percentage of the poverty line, and the poverty gap index the World Bank publishes, all from four aggregate figures.
Enter the number of poor individuals, the poverty line, the total income of the poor, and the total population. The worked example used throughout this page, 1,000 poor people under a line of 2,000 with 1,500,000 of combined income in a population of 10,000, returns a shortfall of 500.00 per poor person and a poverty gap index of 2.50%. The tool is pre-filled with those figures so you can verify every step before entering your own.
Use consistent units: if the poverty line is annual income, total income of the poor must be annual too. Results describe the depth of poverty in the measured population, not the cost of any specific program.
Quick Answer
Key takeaways
- The headcount says how many are poor. The gap says how poor they are. Policy sized on the headcount alone is sized blind.
- Three report forms describe the same shortfall: currency per poor person, percent of the poverty line, and the poverty gap index over the whole population.
- The index equals headcount multiplied by the average proportional shortfall, exactly as the World Bank's Poverty and Inequality Platform defines it.
- The gap is an average: it does not move when income shifts between poor people, so pair it with the squared gap when distribution among the poor matters.
- Quick Answer
- How to use the average poverty gap calculator
- The formula, in the World Bank's Foster-Greer-Thorbecke form
- Worked example: a region of 10,000 people
- Why the gap beats the headcount for budgeting
- Absolute lines, relative lines, and honest limits
- What competing calculators miss
- Frequently asked questions
- Add This Calculator to Your Website
- References
How to use the average poverty gap calculator
Enter four aggregate figures from a survey or a published table, then press Calculate. You need the number of poor people, the poverty line, the total income of those poor people, and the total population. No household-level microdata is required.
Keep the period and the welfare measure aligned. An annual poverty line needs annual income totals; a consumption-based line needs consumption totals. The calculator guards the two mistakes that quietly wreck this statistic: it refuses a poor count larger than the population, and it flags a total income of the poor that exceeds the line multiplied by the number of poor, which means the group or the period is mismatched.
The formula, in the World Bank's Foster-Greer-Thorbecke form
The poverty gap index is the P1 member of the Foster-Greer-Thorbecke family. The World Bank's Poverty and Inequality Platform methodology handbook defines it as the average, over the whole population, of each poor person's shortfall expressed as a share of the poverty line, with the nonpoor counted as zero.
Average shortfall per poor person. (Poverty line multiplied by number of poor, minus total income of the poor), divided by the number of poor. Worked example: (2,000 x 1,000 - 1,500,000) / 1,000 = 500.00.
Share of the line. Divide the shortfall by the poverty line: 500.00 / 2,000 = 25.00%. This form travels across countries because it does not depend on the local line's size.
Headcount ratio. Number of poor divided by total population: 1,000 / 10,000 = 10.00%.
Poverty gap index. Headcount multiplied by the proportional shortfall: 10.00% x 25.00% = 2.50%. Multiply the index by the line for the per-capita transfer cost: 50.00.
Worked example: a region of 10,000 people
The calculator is pre-filled with this region, and the table below is exactly what it returns.
| Figure | Value |
|---|---|
| Average shortfall per poor person | 500.00 |
| Shortfall as share of the poverty line | 25.00% |
| Headcount ratio | 10.00% |
| Poverty gap index (PGI) | 2.50% |
| Per-capita cost to close the gap | 50.00 |
Read the last row carefully. It does not say each poor person needs 50.00. Each poor person needs 500.00 on average; spread across all 10,000 residents, the bill is 50.00 per resident. That is the theoretical minimum budget with perfectly targeted transfers, which is why development economists size programs from the gap rather than from the headcount. Readers combining group figures like these should also know how the averaging itself behaves: the average of percentages calculator covers the traps in averaging rates across groups of different sizes.
Why the gap beats the headcount for budgeting
Two regions can both report 10% of people below the line while needing wildly different budgets. In one, poor incomes cluster just under the line and small transfers finish the job. In the other, incomes sit near zero and the same headcount hides a far deeper problem.
The World Bank's DataBank glossary describes the published poverty gap the same way this tool computes the index: the mean shortfall from the poverty line, counting the nonpoor as zero, expressed as a percentage of the line. Where the inputs come from matters as much as the arithmetic. Group totals usually start as a population aggregate, and the aggregate income calculator is the companion step when you are building the income total from components. When a report gives you a rate instead of the counts behind it, the average rate calculator is the safer place to combine rates across periods than a quick mean in a spreadsheet.
Absolute lines, relative lines, and honest limits
An absolute line is a fixed money amount, like the World Bank's international lines used for global comparison. A relative line moves with the society around it, commonly half of median income in OECD work. The same population produces different gaps under each, and neither is wrong; they answer different questions.
Three limits apply to every version of this statistic, including this one. The gap assumes incomes are measured well, and survey income at the very bottom is noisy. It treats a currency unit as equally valuable to every poor person. And, as the FAQs note, it is blind to distribution among the poor: the squared gap exists precisely because the plain gap cannot see that.
What competing calculators miss
The ranking field for this search is thin, and the tools that exist each report only part of the picture.
Winning move 1: all three report forms, one input set. Brave Calculator's version takes an average income of the poor and returns a single percentage. That hides the currency shortfall a budget officer actually needs, and it never computes the headcount or the per-capita closing cost. This tool returns all of them from four aggregate inputs.
Winning move 2: aggregate inputs, not microdata. The deep guides, such as NumberAnalytics' poverty gap walkthrough, work household by household with spreadsheet or code steps. Useful for researchers with survey files; useless for a reader holding a published table of totals. This calculator is built for the table.
Winning move 3: validation that catches impossible data. If total income of the poor exceeds the line times the headcount, the inputs cannot describe the same group, and a naive tool would print a negative gap. This one stops and tells you which check failed.
Frequently asked questions
It is the average amount by which a poor person's income falls below the poverty line. With a line of 2,000, 1,000 poor people, and total income of the poor of 1,500,000, the average shortfall is 500.00 per poor person, which is 25.00 percent of the line.
The poverty gap index averages the shortfall over the whole population, counting everyone who is not poor as zero. It equals the headcount ratio multiplied by the average proportional shortfall among the poor. In the worked example, 10.00 percent multiplied by 25.00 percent gives a poverty gap index of 2.50 percent.
The headcount ratio only counts how many people are poor. The gap measures how poor they are. Two regions can share a 10 percent headcount while one group's incomes sit just under the line and the other's sit near zero, and the gap separates them immediately.
It is the poverty gap index multiplied by the poverty line: the budget per person across the whole population that, with perfectly targeted transfers, would lift every poor person exactly to the line. In the example it is 2.50 percent of 2,000, which is 50.00 per person. Real programs cost more because targeting is never perfect.
No, not if the group is defined as people below the line. If it does, an input is wrong: usually the income total covers a different group or a different period than the headcount. The calculator flags this instead of returning a negative gap.
No. It is an average shortfall, so moving income from a very poor person to a slightly less poor person leaves it unchanged. The squared poverty gap, the P2 member of the same Foster-Greer-Thorbecke family, weights deeper shortfalls more heavily and does respond to distribution among the poor.
Use one welfare measure consistently: the World Bank's global work is mostly consumption based for low income countries and income based for richer ones. Pick the line that matches your question: an international line such as the World Bank's for cross-country comparison, or a national line for domestic policy. Mixing lines or measures between periods breaks the comparison.
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References
- World Bank, "Poverty and Inequality Platform Methodology Handbook: Survey Estimates". World Bank PIP Methodology: Poverty Gap Index. Accessed October 2026.
- World Bank, "Poverty and Inequality Platform Methodology Handbook". World Bank PIP Methodology Handbook. Accessed October 2026.
- World Bank DataBank, "Metadata Glossary: Poverty Gap Indicator Definition". World Bank DataBank: Poverty Gap Definition. Accessed October 2026.
- World Bank DataBank, "LAC Equity Lab Glossary: Poverty Gap". World Bank DataBank: Poverty Gap Glossary Entry. Accessed October 2026.
- Number Analytics, "Mastering the Poverty Gap Index: Calculation and Use". Number Analytics: Poverty Gap Index Guide. Accessed October 2026.