Hammock Hang Calculator

Find the ridgeline length, strap height, and suspension length for a comfortable hammock hang using the standard 30-degree rule and 83% ridgeline rule.

Quick Facts

30-degree rule
Hang each strap at roughly 30° from horizontal
Produces the sag needed for a comfortable diagonal lay.
83% ridgeline rule
Ridgeline ≈ 0.83 × hammock length
Reproduces a 30° sag regardless of anchor spacing.

Your Results

Calculated
Ridgeline length
-
83% of hammock length
Strap height per tree
-
Attachment point above ground
Suspension length per side
-
Strap/rope from anchor to hammock end
Total suspension needed
-
Both sides combined

Ready

Enter your anchor distance, hammock length, and hang angle, then press Calculate.

About the Hammock Hang Calculator

This tool applies the two rules of thumb that most hammock camping guides teach for a comfortable hang: the 30-degree rule for suspension angle and the 83% ridgeline rule for sag. Enter the distance between your anchors (trees, posts, or a stand), your hammock's end-to-end length, your target hang angle, and your desired sit height, and the calculator returns the ridgeline length, the height to attach each strap, and how much suspension line you need per side.

The formula

Treating each side's suspension line as a straight segment (the standard simplification used by hammock hang calculators, rather than modeling the true catenary curve) at angle θ from horizontal:

  • Ridgeline length R = 0.83 × hammock length. This is the recommended distance between the hammock's two suspension points that reproduces a 30° sag.
  • Horizontal run per side = (anchor distance − R) ÷ 2 — the horizontal gap on each side between the anchor and the hammock's resting end point.
  • Suspension length per side = horizontal run ÷ cos(θ).
  • Sag per side = horizontal run × tan(θ).
  • Strap height on the tree = desired sit height + sag.

Why 30 degrees

A shallow angle (well under 30°) pulls the hammock nearly straight and flat, which forces you to lie parallel to the fabric edges and creates pressure on your shoulders and calves. A steep angle (well over 30°) creates a deep sag that wraps the sides up around you like a taco. Around 30° hits a widely recommended middle ground: enough sag to let you lie on the diagonal, which flattens your spine and is the most common comfort recommendation among hammock campers.

Practical notes

Real webbing and rope stretch slightly under load, and trees are rarely perfectly plumb, so treat the suspension length as a starting point and adjust a few inches once you're actually testing the hang. If the calculator reports that your anchors are too close together, either move to trees farther apart or choose a shorter hammock — the anchor distance must exceed the ridgeline length for any positive sag to exist.

Frequently Asked Questions

What is the 30-degree rule for hanging a hammock?
The 30-degree rule says the suspension line on each side should leave the tree at roughly a 30° angle from horizontal. That angle produces enough sag to let you lie on a diagonal, which flattens your body and is widely recommended as the most comfortable hang for camping hammocks. Shallower angles pull the hammock tight and flat; steeper angles create a deep, wrap-around sag.
What is the 83% ridgeline rule?
The 83% rule states that a fixed ridgeline (the cord connecting the hammock's two suspension points across the top) should be about 83% of the hammock's end-to-end length. That ratio reproduces the sag of a properly hung 30° angle no matter how far apart the anchors are, which is why many hammocks ship with a fixed ridgeline sized this way.
How is strap height on the tree calculated?
Strap height equals your desired sit height off the ground plus the vertical sag contributed by the hang angle. The sag comes from taking half the leftover distance between the anchors and the ridgeline, then multiplying by the tangent of the hang angle.

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