Force on a Slackline

We sometimes get asked how much force is really on a slackline, or how tight or long a slackline can be rigged safely. While we can only give general guidelines, we have provided a quick way of getting an estimate below.

Before continuing you should be aware that there are certain limitations of this force calculator. First, it assumes the person is in the middle and is standing perfectly still. Bounces, walking, surfing and any other movement will alter the load. Second, it fails to consider that forces change when loads are placed near the ends of the line instead of the middle. Lastly, this calculator only succeeds in calculating the lowest force that would be put on the line under the given scenario, not the worst. Please keep that in mind when calculating anything near the maximum load your slackline should handle. For more information about the forces involved on slacklines check out of Slackline Load Tests.

As you can see from above, there are three main factors used to determine the load on a slackline. These are: line length, weight of slacker and the sag in the line. Using these pieces of information, we can use trigonometry to calculate the static load. The general rules regarding slackline loads is that as the lines get longer, the slacker gets heavier or there is less sag in the middle of the line the forces go up. This system has its limitations, such as it assumes you are standing still in the middle of the line, but it has been field checked with load scales and is normally very accurate. We recommend that you stay below 1,250 lbs of expected tension. Do not exceed this load or injury / product damage may result.

The inspiration for this page was works from Eric Matthes. His original Analysis of Static Slacklines provides more information on the formulas used as well as a nifty graph comparing length and sag of different setups. The formula from his page was used to create this dynamic calculator.

"Hi Joe. I just got the 30 ft intro kit, and I have to say, it's fantastic. Very easy to set up, and beginner friendly." - Elliott More Gear Reviews