Here is a nicely formed redwood on a slope at Prairie Creek Redwoods State Park. There are few redwoods this large up away from creeks. The name for this one will be Spartacus. In 2010, Chris Atkins did a preliminary measurement for this of 96 meters or 314.93 feet tall. And Michael Taylor measured the first 110' of the trunk, looking from North to South at the narrow side. So far, the narrow measurement indicates 15,000 to 16,000 cubic feet of wood in the first 110' of the trunk. The circumference near dbh is 62' or 19.73' diameter. I knew this redwood was pretty big when first spotted. But was surprised how large the trunk was when we first wrapped a tape. The camera lens exaggerates the taper in the image below, where I'm standing next to a log near the base.
Update: March 2011 (weekend Tsunami was discovered), I went uphill to photograph the bole. The trunk actually increases diameter again, about 140 feet up, storing a lot of wood above.
If you look around online there are some handy frustum calculators. The example below is one I made use of for the initial measurements from Taylor until more numbers are available. Basically, redwoods can be represented like flat top cone sections and each measured individually. As if the redwood were sliced into sections. The measurements needed for each section are height, top radius and bottom radius. A radius is half the diameter.
This redwood is not as large as the biggest titans like Del Norte Titan or Bull Creek Giant. But for comparison, just the first 110' of the trunk is not far from the entire 18,000 to 19,000 cubic feet of the 379' trunk on Hyperion. I'm curious how this compares to Adventure, which is only 20 feet taller, with a 16.5 ft. DBH.