About the data

Forbes World's Billionaires, annual lists 2001–2026

From the Gapminder billionaires dataset's raw Forbes files (open-numbers/ddf--gapminder--billionaires, commit 23e1da4141), which mirror Forbes' own list endpoint. Each file is Forbes' whole person database with the year's net worth filled in for that year's listees. Files from 2010 onward match Forbes' published counts exactly; 2001–2009 are short by 15–25% because people who dropped off before Forbes built a profile are missing (530 of the 691 2005 listees, for example). The pre-2001 files are unusable. Headline counts for 1987–2009 are Forbes' published totals as compiled by secondary sources, marked approximate where those sources disagree.

Forbes profiles via rtb-api

komed3/rtb-api mirrors Forbes' real-time billionaire profiles since November 2019 (5,092 profiles at commit af26b1bb1c): birth dates, citizenship and residence, the self-made flag and the 1–10 self-made score, industry, and source of wealth. 3,416 of the 3,428 people on the 2026 list have one; 3,350 have a birth date.

Peterson Institute Billionaire Characteristics Database

Freund and Oliver's hand-coded database (1996, 2001, and 2014 lists), distributed as a CSV by CORGIS. Its inherited field (father, spouse, third generation, and so on) is the ground truth used to calibrate Forbes' binary flag.

Federal Reserve

Household and nonprofit net worth from the Financial Accounts (Z.1, FRED series BOGZ1FL192090005Q) and the wealth of the top 0.1%, top 1%, and bottom 50% from the Distributional Financial Accounts (WFRBLTP1246, WFRBLT01026, WFRBLB50107, and the share series). Quarterly; each Forbes March list is matched to that year's first quarter.

Forbes editorial lists

The hired-hand billionaires lists (26 names, February 2024; 48 names, May 2025, of which the named newcomers were recoverable) and the 2026 celebrity billionaires list (22 names). Population for per-capita figures is Gapminder's.

A current list's age distribution is not the distribution of ages at which people became billionaires. “US citizen” (Forbes) is not “US household” (the Fed). And the classification of a 2026 fortune is not carried back onto earlier years' net worths.

1. Forbes flags the person not self-made (types “inherited” and “inherited and growing”) → inherited or received. Two divorce settlements (MacKenzie Scott, Melinda French Gates) are kept in this group with a reviewed override noting the transfer type.
2. Named on Forbes' 2026 celebrity billionaires list → celebrity, athlete, or creator. This follows Forbes' editorial call and outranks founding, so Vince McMahon (WWE), George Lucas, and Tyler Perry sit here rather than with company founders.
3. Named on Forbes' hired-hand lists, or scored 6 of 10 by Forbes (“hired hand”) → hired executive or early employee. A floor, since the 2025 list is only partly recoverable.
4. Forbes flags the person self-made and the Forbes industry is Finance & Investments → founded a finance or investment business. In practice this is Forbes' industry label, which mostly means hedge funds, private equity, asset managers, brokerages, insurers, banks, and crypto exchanges, but also sweeps in Bloomberg LP and Peter Thiel; it is not about owning investments, which nearly everyone does.
5. Otherwise self-made → founded or built an operating company. Outside the US this includes hired hands and celebrities Forbes has not listed, and in Russia and Central Asia it includes owners of privatized Soviet-era assets that Forbes flags self-made.
6. No Forbes flag yet (mostly people new to the list) → not classified.

Ruleset 2026-09-04.1. Applied to the March 2024 US list the same rules give 368 founded or built an operating company ($2.78T), 171 founded a finance or investment business ($1.13T), 234 inherited or received the fortune ($1.53T), 27 hired executive or early employee ($228B), 13 celebrity, athlete, or creator ($30.5B) — within a handful of people of an earlier, independently hand-checked run on that list (370 / 172 / 235 / 24 / 12; $2.78T / $1.14T / $1.54T / $0.22T / $0.03T).

• Baseline: everyone on any list from 2001 through 2010, or named in the Peterson database's 1996 or 2001 lists (34 people), is excluded — their first billion predates the window, and the pre-2010 files are incomplete anyway. Entrants are people whose first appearance is 2011–2026.
• US-connected means Forbes recorded the person's country as the United States on at least one list.
• People stay in the cohort if they later fell off the list, died, or changed citizenship. Combined entries (“X & family”, siblings) are dropped: 42 worldwide.
• Age at entry is exact where Forbes publishes a birth date (828 of 876 Americans); otherwise it is the list year minus a birth year inferred from the reported age and the date the profile was fetched, with a ±1 year band (39 people) or wider when Forbes' reported ages disagree across years (9).
• A March list can only reveal that someone crossed $1 billion during the prior year, so entry ages are late by up to a year. The curve's point estimate averages adjacent-list values; its lower edge counts everyone a year older and its upper edge two years younger.
• Sensitivity: widening the window to 2006–2026 (baseline 2001–2005) gives 1,039 Americans, median age 58, 12% by 40 and 57% by 60, versus 14% and 58% in the primary run. The wider window leans on the incomplete 2006–2009 files and so under-represents people who arrived then and left quickly.

425 US citizens on the 2014 list matched by name to the Peterson database and carrying a Forbes flag; agreement 95.8%. Across all countries (1339 matches) agreement is 93.8%; the non-US rates are used for non-US entrants (914 matches: 83.0% and 1.8%). Because the Forbes flag comes from current profiles, this calibration covers people still tracked by Forbes after 2019: in the Peterson sample, 29.7% of people with a current flag inherited, against 32.2% of those without one. The ranges shown on the age page propagate only this calibration uncertainty — not entity-matching errors, changes in Forbes' practice over time, mixed fortunes, or small bucket sizes.

• Net worths are Forbes' estimates, mostly from public shareholdings and private-company valuations, and move daily; the list is a March snapshot.
• The $1 billion threshold is nominal. In 2026 dollars the 1987 bar was about $2.9 billion, so the count series partly measures inflation; the overview page gives the real-terms comparison and the wealth page a fixed-count sensitivity.
• The Fed's top-0.1% and bottom-50% figures come from the Distributional Financial Accounts, whose survey base excludes the Forbes 400; the top-0.1% comparison is indicative, not exact.
• Forbes counts by citizenship and lists some fortunes as families; the Fed measures the household sector. Shares of US wealth are therefore shown to one decimal at most.
• The historical headline counts before 2010 are as reported and, before 2001, come from secondary compilations with occasional disagreements.
• Country and industry are Forbes' current labels; a person who moved or diversified is counted where Forbes now puts them.
• Dollar figures are current dollars, not inflation-adjusted.

Built 2026-09-04. Code and pipeline: github.com/mwg1378/billionaires.