How to calculate rent burden for a county: quick answers
Short, exact answers to the questions people ask before they build a rent burden figure from the County List with Demographics. Each one names the columns it uses. For the full spreadsheet walk-through, see the guide to reproducing our county affordability figures in Excel.
How do I calculate rent burden for a county?#
Divide a year of rent by a year of income: median_gross_rent × 12 ÷ median_household_income. The result is the share of the median household's income that the median rent would take. In a spreadsheet, with rent in column C and income in column D, it is =C2*12/D2, formatted as a percentage.
Why do I multiply the rent by 12?#
Because the two columns use different periods. median_gross_rent is a monthly figure. median_household_income is an annual figure. If you divide one by the other without the × 12, the answer is 12 times too small. Multiplying rent by 12 turns it into a year of rent, so both sides cover the same period.
The column-definition file that ships inside the download describes median_gross_rent as typical monthly rent (five-year average).
What does a worked example look like?#
Two counties, using the exact columns:
- Bronx County, NY: 1,436 × 12 = 17,232, and 17,232 ÷ 49,036 = 0.351, or 35.1%.
- Oldham County, KY: 1,142 × 12 = 13,704, and 13,704 ÷ 121,491 = 0.113, or 11.3%.
Both match the figures on our Highest rent burden and Lowest rent burden pages. Use them as a check on your own sheet.
Which columns do I need, and what are they called?#
Three, and the names are exact: median_gross_rent, median_household_income, and a county identifier such as name (or county_fips) so you know which row is which. Add state_name if you want to filter to one state. Type the column names as written when you reference them in a script or a lookup.
What does the result mean, and what doesn't it mean?#
It means the median rent in a county, over a year, as a share of that county's median household income. A reading of 35.1% says the typical rent there is about 35 cents of every dollar of typical income.
It does not mean the median household spends 35.1% of its own income on rent. It is a ratio of two medians, not the median of every household's own rent share, and renters are not the same group as all households. Describe it as "median rent as a share of median household income" and the sentence will hold up.
How exact is the figure? Can I say one county is higher than another?#
All three inputs are Census survey estimates, which carry a margin of error. Treat small gaps between two counties with caution, and don't report a few tenths of a point as a real difference. Round the result to one decimal place, as our pages do, and don't report more precision than that.
Does every county have a rent figure? What about cities?#
Counties: coverage in the County List with Demographics is effectively complete, at 97.3% of counties. A few counties have a blank in median_gross_rent. Filter them out before you calculate, and don't treat a blank as zero.
Cities: coverage depends on the type of place, so there isn't one number for cities. Incorporated places are covered at 85.6%, census-designated places (CDPs) at 46.0%, and townships not at all: none of the 16,157 townships has a rent figure. If you are working with city rent data, check which category each place falls in before you trust a blank or a gap.
Where do I get the file, and is there a step-by-step?#
The County List with Demographics is $199, one-time, as a UTF-8 CSV inside a .zip. The free sample shows the columns before you buy. For the steps from file to finished sheet, follow the Excel guide. To get every county, open the County List with Demographics.