The New Shepard rocket of Blue Origin is a suborbital crewed capsule targeting both the research and tourism market. Like most companies, Blue Origin is quite secretive about their parachute sizes and performance. Therefore Chutes.nl set out to reverse engineer the size of New Shepard's parachutes.
When looking at the NS-15 mission one can find two data points during which the capsule has a near stable velocity. Just before drogue deployment and just before the ground. These points are 212 mph and 8500 ft (94.8 m/s and 2590.8 m) and 16 mph and 199 ft (7.15 m/s and 60.65m). From the first data point, we know that the capsule is falling at a stable dynamic pressure and without parachutes. With the assumption of an exponential atmosphere, thus a density of about 0.88 kg/m3, a dynamic pressure of 3979.4 Pa can be calculated. Assuming a capsule mass of 3630 kg (https://flightclub.io/build/editor/launchvehicle) one can determine that the capsule would have a drag area of 8.94 m2.
From the second data point, we know that the capsule with all three parachutes deployed falls significantly slower. Using the same method one can determine a terminal dynamic pressure of 31.1 Pa leading to a total drag area of 1145.1 m2. This means that the parachutes have a drag area of 1136.1 m2.
Assuming the ringsails have a drag coefficient of 0.8 this would lead to a single parachute area of 473.4 m2 or diameter of 24.5 m. Now of course there are unknowns in this approach. To remove some of these the mass is varied from 3500 kg to 4000 kg leading to a diameter range of 24 to 25.8 m. This would put the New Shepard parachutes around the size of those on Soyuz and Apollo, just below Shenzhou and just above Mercury.