HOW many people in the world have bank accounts and what do they use them for? You would think there would be answers to those questions, given that banking is the quintessentially global business, and is important not only in the West but in developing countries, where banks can help poor people save, borrow and invest. Yet, until now, data on the global reach of financial institutions have been limited. The IMF publishes a financial access survey of depositors and borrowers. But there is little about how much people save or why they borrow. Especially little is known about the banking practices of the poor, women and young people. So a big data hole got plugged last year when the Gates Foundation, the World Bank and Gallup World Poll carried out the biggest survey yet of how people save, borrow, make payments and manage risk. The results have just appeared.

Roughly half of all adults in the world have an individual or joint bank account, according to the new Global Findex database. As one would expect, there is a big difference between banking in the West (where is 89% of adults have accounts) and the developing world (41%). The difference is wider still when it comes to credit cards; half of adults have them in the West, just 7% in developing countries.

Within countries, levels of banking climb sharply with income and education. In Africa, for instance, 55% of people with tertiary education have bank accounts. But only just over 10% of those with primary or no education do.

Banking displays a significant gender gap. In developing countries, 46% of adult men say they have an account, but only 37% of women. The gap is largest in South Asia and the Middle East and north Africa. It is a bit lower in the rest of Africa, where banking penetration as a whole is low: 27% of men have accounts, 22% of women.

The bigger surprises concern how people use banks and other financial institutions. One might expect that, outside the West, banks (which tend to be relatively expensive) would be used largely for business. Not at all. The vast majority of people in developing countries—88%—say they use banks solely for personal use. The commonest reason for taking out a loan, for example, is to pay for family emergencies (typically someone falling ill). That is followed by school fees, home construction and the expenses of a wedding or funeral. In Africa, 38% of those with bank accounts say they use them to receive remittances from family members abroad. One particularly important reason for having an account in Europe, Central Asia and Latin America is to bank money from the government, either salaries or benefits.

In comparison, banks do not seem to be used so much for what seems like a basic purpose: saving money. More than a third (36%) of adults said they had saved some money last year. But only a fifth (22%) said they used a bank or other formal financial institution to do it; 29% saved, but not at a bank (presumably they put the money under the mattress or used it to buy jewellery). A popular form of saving in Africa was the savings club. A group of people get together to bank their pennies regularly and each month the club pays out the entire pot to each member in turn. 

The modest use of banks for saving points to what seems like the overall story that emerges from the research. The extent of banking around the world is much patchier and less predictable than one might expect. Of course, bank usage tends to increase with income both globally and within countries. But income does not seem to be the sole determinant. Ghana and Benin are near-neighbours in West Africa and have similar levels of income. Yet Ghana has three times as many banks per head of the adult population as Benin does. Nigeria and Cameron are neighbours and have roughly the same level of banking among the poorest fifth of their populations (17% of the lowest quintiles in each country have bank accounts). Yet rich Nigerians are almost three times more likely than rich Cameroonians to have accounts.

The moral is that other things matter as well as income. Policy makes a difference: does the government make it easy for banks to spread? The banks themselves make a difference: after lack of money, one of the commonest reasons people give for not having an account is the paperwork. And mobile phones make a huge difference. In Kenya, a stunning 68% of adults say they have used a mobile phone to send or receive money in the past 12 months. More than half of them have bank accounts.