Top-of-steel slope / elevation

What this calculator does

For a beam on a constant slope, enter the top-of-steel elevation at each end, the run between them, and how far along you are; the page interpolates the elevation at that point. It gives decimal feet and feet-inches-sixteenths, and prints the slope three ways — percent, inches per foot, and 1:n — so it matches however the drawings say it.

Worked example

TOS at A = 100.00 ft, at B = 101.50 ft, run 60 ft. At 25 ft from A: 100.00 + 1.50 × (25/60) = 100.625 ft = 100'-7 1/2". The slope is 2.5%, 0.30" per foot, 1:40.

Common questions

Is this the elevation at the centerline or the top of the flange?

Whatever you entered at A and B. If those are top-of-steel at the flange, the answer is top-of-steel at the flange. It does not add or subtract a deck, a camber, or a bevel.

What if the beam is cambered?

Camber is not a slope. The tool assumes a straight line between A and B; a cambered beam sits above that line in the middle by the camber ordinate at that point.

Can I run it uphill and downhill?

Yes — enter the actual elevations and it handles either direction; a falling beam just shows a negative slope.