Sine Bar Calculator

A sine bar sets an angle by raising one roller on a gage block stack. The stack height is H = L × sin(θ), where L is the roller center distance (5 in, 10 in, 100 mm or 200 mm are common). Enter either the angle or the stack you have, and the tool gives the other, rounded to a stack you can actually build.

Sine bar length I know the Angle (degrees)

Examples

Sine bar	Angle	Stack (H = L sin θ)
5 in	15°	1.2941 in
5 in	30°	2.5000 in
5 in	40°	3.2139 in
100 mm	15°	25.882 mm
200 mm	15°	51.764 mm

Good practice

Rounding the stack to 0.0001 in or 0.001 mm changes the angle by a few arc-seconds; the tool shows exactly how much.
Sine bars lose accuracy at steep angles (above about 45° small height errors become large angle errors). For steep angles, set the complement or use a sine plate made for it.
Wring the stack carefully and keep it at the same temperature as the bar: how to wring gage blocks · temperature correction.
Metric bar? See metric gage block stacks.

General shop information only. Check your sine bar's certified roller center distance.