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Methodology

How BorderStat works

A transparent, end-to-end look at how we gather, verify and present the numbers — and the principles that keep them honest. Behind every simple chart is months of careful, unglamorous work.

The short version

Everything on BorderStat is a reported figure — gathered, cross-checked and never fabricated.

A nine-person core team — supported by hundreds of volunteers across the world — reads source releases, matches country codes, aligns definitions, converts currencies and reconciles numbers that rarely agree at first glance. This page explains that pipeline, step by step, so you can trust what you see and know exactly what it does — and does not — mean.

The pipeline

From source to screen

Six stages every figure passes through before it appears on the site.

Collect

We pull data from official institutions and independent non-commercial funds - only reported values, straight from the primary release.

Verify

Each value is compared across sources. Where they disagree, our investigators trace the figure back to its origin before we accept it.

Standardise

Country codes are aligned, all money is converted to USD, and every date is normalised to DD.MM.YYYY so countries are truly comparable.

Classify

We separate stock (a count at a moment) from flow (movement over time) and label each metric so the two are never mixed up.

Publish

Clean, labelled figures are rendered into calm, readable charts, tables and the interactive atlas.

Revise

When a source issues an update or correction, we refresh the number. The site reflects the latest reported reality, not a frozen snapshot.

Definitions that matter

Stock vs. flow

Confusing these two is the single most common mistake in migration data. We never do.

Stock

A count at a moment

The total number of people present at a point in time — for example, all refugees living in a country today. It answers “how many are here now?”

Flow

Movement over a period

The number of people arriving or leaving during a span of time — for example, arrivals over one year. It answers “how many moved, and when?”

Conventions

The rules we never break

  • All monetary amounts are stored and displayed in USD.
  • All dates use the DD.MM.YYYY format.
  • No fabricated estimates — missing data stays visibly missing.
  • Stock and flow figures are kept strictly separate and labelled.
  • Figures may be revised as sources publish updated data.
Official sources Non-commercial funds Cross-checked Clearly defined Comparable
Reading the atlas

What the shading means

Has a figure. The country has a reported value for the metric you selected.
Tracked, no value. We follow this country, but it has no figure for that particular metric.
No data yet. Nothing has been reported for this country so far.

None of these states is an error — each one simply reflects what has, and has not, been reported.

Glossary

Key terms in plain language

Refugee

A person recognised as needing international protection and counted as present in a host country.

Asylum seeker

A person who has applied for protection and is awaiting a decision.

Migrant stock

The total number of migrants present in a country at a given point in time.

Migration flow

The number of people arriving or leaving over a defined period, such as a year.

Net migration

Arrivals minus departures for a period; positive means net inflow.

Border-related spending

State expenditure connected to borders and migration, reported in USD.

Questions & answers

Q&A

The things people ask us most often about how BorderStat is made.

Where do your numbers come from?
From official institutions (national statistics offices, government budgets, UNHCR, the World Bank) and from independent, non-commercial funds and partners. Every figure is a reported value, never an invented estimate.
Do you ever make up or estimate missing data?
No. When a country has no reported figure for a metric, we leave it blank and label it clearly. We would rather show a gap than a guess.
What is the difference between "stock" and "flow"?
A stock is a count at a point in time (for example, the total number of refugees present in a country). A flow is movement over a period (for example, arrivals during a year). We keep the two separate and labelled so they are never confused.
Why is a country greyed out or shown differently on the atlas?
A tracked country with no figure for the selected metric is shown as "tracked, no value", while a country with no data at all appears faint. Neither is an error - it simply reflects what has been reported.
What currency and date format do you use?
All monetary values are stored and shown in US dollars (USD). All dates use the DD.MM.YYYY format for consistency across countries.
How often is the data updated?
Regularly. Figures are revised whenever our sources publish new or corrected releases, so numbers can change over time.
How do you handle conflicting figures between sources?
Our investigators trace each figure back to its primary release and prefer the most authoritative, most recent official source. Where a genuine discrepancy remains, we favour transparency over a false sense of precision.
Is BorderStat free? Do you sell my data?
BorderStat is free and open to everyone. We do not sell personal data; only anonymous usage analytics are collected to improve the site.
I think a number is wrong. What can I do?
Please tell us. We welcome corrections and data enquiries, and we would rather fix a figure than defend it.

Corrections & data enquiries

Found a figure that looks wrong, or need detail on a source? Reach the people who built this — see the team page.

Meet the team Explore the data
Privacy

Your privacy

BorderStat does not sell personal data. Only anonymous usage analytics are collected, purely to understand what is useful and improve the site.