Measure the attic depth with a ruler and compare against the Climate Zone 5A target of R-49 to R-60. Then check the rim joist and an exterior wall cavity. A blower door test tells you about air leakage, which usually matters more.
More detail
Three checks anyone can do in twenty minutes, in the order that matters. The attic. Push a ruler down to the ceiling drywall and read the depth. Then identify the material: loose gray-brown fluff is cellulose at roughly R-3.5 per inch, loose pink or yellow is blown fiberglass at roughly R-2.5 to R-3 per inch, batts between joists are typically R-11 to R-19 total depending on age. Multiply and compare. In Climate Zone 5A the code target is R-49 to R-60 depending on the adopted cycle, which means 14 to 20 inches of cellulose. A great many houses in Greater Columbus and Central Ohio measure 6 to 9 inches. The rim joist. Look at the band of framing at the top of the basement or crawl wall. Bare wood means an uninsulated continuous perimeter gap, which is common in the mix of pre-war stock in the older Columbus neighborhoods, mid-century ranches in the inner suburbs, and large 1990s-onward subdivisions in the outer counties. The walls. Turn off the breaker, remove an outlet cover on an exterior wall, and look into the cavity with a flashlight. Empty, settled, or full tells you most of what you need. What these checks cannot tell you is air leakage, which is usually the larger number and is invisible. A blower door test depressurizes the house with a calibrated fan and reports air changes per hour at 50 pascals. Paired with an infrared scan on a cold day, it produces a ranked list of where the losses actually are rather than a guess. The reason to measure before buying anything: the highest-return work in an older house is frequently air sealing the attic plane, which is cheap, followed by topping up loose fill, which is also cheap. Both get skipped when the conversation starts with a product instead of a measurement.