{"slug":"the-rule-of-72","qid":"inflation_halving","label":"Ten-year US inflation rate and the time to halve a dollar's purchasing power","post_title":"The Rule of 72 (and Where It Breaks)","post_url":"/blog/the-rule-of-72#q-inflation_halving","columns":["year","inflation_rate_pct","exact_halving_years","rule_of_72_years"],"rows":[{"year":2000,"inflation_rate_pct":2.8,"exact_halving_years":25.1,"rule_of_72_years":25.7},{"year":2001,"inflation_rate_pct":2.66,"exact_halving_years":26.4,"rule_of_72_years":27.1},{"year":2002,"inflation_rate_pct":2.51,"exact_halving_years":27.9,"rule_of_72_years":28.6},{"year":2003,"inflation_rate_pct":2.45,"exact_halving_years":28.7,"rule_of_72_years":29.4},{"year":2004,"inflation_rate_pct":2.45,"exact_halving_years":28.6,"rule_of_72_years":29.3},{"year":2005,"inflation_rate_pct":2.51,"exact_halving_years":28,"rule_of_72_years":28.7},{"year":2006,"inflation_rate_pct":2.54,"exact_halving_years":27.6,"rule_of_72_years":28.4},{"year":2007,"inflation_rate_pct":2.59,"exact_halving_years":27.1,"rule_of_72_years":27.8},{"year":2008,"inflation_rate_pct":2.82,"exact_halving_years":24.9,"rule_of_72_years":25.5},{"year":2009,"inflation_rate_pct":2.56,"exact_halving_years":27.4,"rule_of_72_years":28.1},{"year":2010,"inflation_rate_pct":2.39,"exact_halving_years":29.3,"rule_of_72_years":30.1},{"year":2011,"inflation_rate_pct":2.42,"exact_halving_years":29,"rule_of_72_years":29.7},{"year":2012,"inflation_rate_pct":2.47,"exact_halving_years":28.4,"rule_of_72_years":29.1},{"year":2013,"inflation_rate_pct":2.39,"exact_halving_years":29.4,"rule_of_72_years":30.2},{"year":2014,"inflation_rate_pct":2.28,"exact_halving_years":30.7,"rule_of_72_years":31.6},{"year":2015,"inflation_rate_pct":1.96,"exact_halving_years":35.8,"rule_of_72_years":36.8},{"year":2016,"inflation_rate_pct":1.76,"exact_halving_years":39.7,"rule_of_72_years":40.9},{"year":2017,"inflation_rate_pct":1.69,"exact_halving_years":41.4,"rule_of_72_years":42.7},{"year":2018,"inflation_rate_pct":1.55,"exact_halving_years":45,"rule_of_72_years":46.4},{"year":2019,"inflation_rate_pct":1.77,"exact_halving_years":39.6,"rule_of_72_years":40.7},{"year":2020,"inflation_rate_pct":1.73,"exact_halving_years":40.4,"rule_of_72_years":41.6},{"year":2021,"inflation_rate_pct":1.88,"exact_halving_years":37.2,"rule_of_72_years":38.3},{"year":2022,"inflation_rate_pct":2.46,"exact_halving_years":28.6,"rule_of_72_years":29.3},{"year":2023,"inflation_rate_pct":2.72,"exact_halving_years":25.8,"rule_of_72_years":26.5},{"year":2024,"inflation_rate_pct":2.86,"exact_halving_years":24.6,"rule_of_72_years":25.2},{"year":2025,"inflation_rate_pct":3.11,"exact_halving_years":22.6,"rule_of_72_years":23.1}],"shape":"table","sql":"WITH yearly AS\n(\n    SELECT\n        toYear(date)        AS year,\n        toYear(date) + 10   AS decade_later,\n        avg(toFloat64(cpi)) AS cpi_avg\n    FROM global_markets.inflation\n    WHERE date >= '1990-01-01'\n      AND date <  '2026-01-01'\n      AND cpi > 0\n    GROUP BY year, decade_later\n),\nwindows AS\n(\n    SELECT\n        recent.year                             AS year,\n        pow(recent.cpi_avg / base.cpi_avg, 0.1) AS annual_factor\n    FROM yearly AS base\n    INNER JOIN yearly AS recent ON recent.year = base.decade_later\n)\nSELECT\n    year,\n    round((annual_factor - 1) * 100, 2)          AS inflation_rate_pct,\n    round(log(2) / log(annual_factor), 1)        AS exact_halving_years,\n    round(72.0 / ((annual_factor - 1) * 100), 1) AS rule_of_72_years\nFROM windows\nORDER BY year ASC","computed_at":"2026-10-09T15:39:34.244276+00:00","elapsed":0.003308271}