Tree-Friendly Spacing Calculator
Before you commit to a campsite, work out how far apart two anchor trees should be for your hammock — and get a comfortable range, not just one number.
Look for trees this far apart
Scouting before you set up
Most hang-angle guidance assumes you already have two trees picked out. This calculator runs the same geometry in reverse: starting from your ridgeline length and the strap height you can realistically reach, it works out the tree spacing that would give you a comfortable hang, plus a range around it so real, imperfect tree placement still has room to work. The far edge of the range is rounded down and never goes flatter than 20°, and if your reach would need trees closer than your ridgeline is long, it says so.
Walking a site with this range in mind — rather than picking the first two trees that look roughly hammock-sized apart — is the easiest way to avoid arriving at your spot for the night only to discover your straps would have to go higher than you can reach.
Frequently Asked Questions
Why does tree spacing matter so much?
You sit in the middle of the span, so for a 30-degree hang the strap has to sit tan(30°) times half the tree distance above your seat. Trees farther apart need straps higher than you may be able to reach, and if you hang them lower anyway the hang goes flat and the load on each strap climbs past your weight. Trees closer together than your ridgeline is long leave no room for the hammock at all. Knowing the workable range before you unpack saves you from setting up twice.
What if I can only find trees outside the recommended range?
Walk the site for another pair first. Trees a little closer than the range are easy: attach the straps lower and the angle stays near 30°. Trees farther apart than the range need straps higher than your reach, and the tempting fix, hanging lower and flatter, is the one that multiplies the load. Pick a closer pair instead. If no pair works, a freestanding hammock stand removes the tree-spacing problem entirely.
Does wide webbing actually protect the tree?
Leave No Trace's hammock guide says: "Use 1 inch or wider straps made out of webbing that go around the tree to minimize girdling and damage to the bark and cambium layer." It also says to "Select trees that are at least 6 inches in diameter, preferably with hard bark and no lichen," and "Do not hang your hammock from any dead trees." Check with the land manager too: some parks do not allow hammocks at all.
General guidance only, not a safety rating. Leave No Trace: “Even if your chosen tree looks alive, check above you for dead branches that could fall.” Hang low, never over water or a drop, follow the manufacturer’s instructions, and check the land manager’s rules for hammocks and tree straps.