How high should you hang a hammock?

Hang a hammock so its straps leave the posts at 30 degrees from level, and the rest follows: for posts 12 ft (3.66 m) apart the hooks go about 5 ft (1.52 m) up and the seat settles 18 in (46 cm) off the ground. La Siesta says hang at half the distance between the posts; Trek Light says 5 to 6 ft, with trees 10 to 15 ft apart. Both land near the same hang, because both are really an angle, and the angle matters for a reason neither page puts a number on: at 30 degrees each anchor carries the whole weight in the hammock, and at 15 degrees nearly twice it. The garden around it is planned in outdoor room dimensions.

Measure the angle from level, at the hook#

• The span runs between the inner faces of the two anchors at hook height: trunk, post or wall. Not between hook eyes, and not the hammock's length.
• The hook height runs from the ground to where the strap, rope or chain is fixed.
• The strap angle is between the suspension and the horizontal, where it leaves the anchor.
• The sit height is the lowest point of the hammock with a body in it.

Trek Light writes "a 30 degree angle between the strap and the tree", which read literally is 60 degrees from level. The calculator it sends readers to, Derek Hansen's Hammock Hang Calculator, measures from horizontal: its default 190 lb person at 30 degrees gives 190 lbf of cord tension, true only from level.

For sit height, Trek Light and ENO both give 18 in (46 cm), and ENO says never more than that in use; La Siesta gives 40 to 50 cm (16 to 20 in). It is the hammock's version of the chair seat in seat height, depth and angle: you sit down into it with your feet on the ground.

At 30 degrees each anchor holds the whole weight#

The vertical parts of the two strap forces must add up to the weight W, so each is W/2. A strap at angle a from level delivers only sin(a) of its tension vertically, so the tension in each strap is

T = W / (2 sin a)

and the horizontal pull on each anchor is W / (2 tan a). At 30 degrees sin(a) is exactly one half, so T = W. Hansen's calculator agrees: 200 lbf of cord tension and 173 lbf of what it calls shear for a 200 lb person at 30 degrees, 292 and 275 at 20 degrees, 386 and 373 at 15.

From 45 to 30 degrees the load rises 41 per cent; from 30 to 15 it nearly doubles, and the next 5 degrees add half as much again. That is why the angle rule exists, and Trek Light's "several hundred pounds of pull on each anchor point" matches the 15 to 20 degree rows.

Hook height is sit height plus 0.29 x the span#

Fix the angle and the height follows. Drawn as a V from each hook down to the sitter, the drop from hook to seat is half the span times tan(a), which at 30 degrees is 0.29 x the span:

hook height = sit height + 0.29 x span.

For posts 12 ft (144 in, 3.66 m) apart and an 18 in (46 cm) seat: 18 + 0.29 x 144 = 60 in (1.52 m). This is the geometry Hansen's calculator uses; for a 9 ft 6 in (2.9 m) hammock at 30 degrees it returns 4.4 ft at 10 ft, 5 ft at 12 ft and 5.8 ft at 15 ft, as below.

All rows assume an 18 in (46 cm) seat. The hammock's own length is not in the formula: it decides how much rope is left between hammock and hook, not how high the hook goes.

La Siesta's half-the-span rule is a 35 to 39 degree hang#

La Siesta's guide: "Take the total length of your hammock and subtract 10%: that's the minimum hanging distance", then "Take the distance (X), divide it by two, and you've got the ideal hanging height (Y)". Its example is a 350 cm (11 ft 6 in) double needing "at least 300 cm" (9 ft 10 in).

The distance rule is a 30 degree rule. Hung with no rope between hammock and hook, a hammock of length L across a span D leaves the anchors at the angle whose cosine is D/L. La Siesta's example, 300 over 350, is 31 degrees, and Hansen's calculator at 30 degrees spreads a 350 cm hammock's ends 303 cm apart. The rule as written, less 10 per cent, gives 315 cm and 26 degrees; the example is stricter than the rule, at 14 per cent.

The height rule puts the hooks higher than 30 degrees needs, by 7 to 20 in (18 to 51 cm) across the 10 to 15 ft range in the table above. With the seat kept at 18 in by letting out rope, the hang steepens to 35 to 39 degrees and each anchor carries 80 to 87 per cent of the weight instead of all of it. For drilling fixed hooks that is the right way to err: rope can lower a hammock from a high hook but cannot raise it from a low one.

So the rules do not disagree: Trek Light's 5 to 6 ft is the 30 degree column, rounded up at the short end, and La Siesta's is a few degrees steeper. Half the span fails only on long spans, where 15 ft (4.57 m) apart puts hooks at 7 ft 6 in (2.29 m), out of reach.

Span, hook height and anchor load by hammock type#

A gathered-end hammock, fabric bunched to a point at each end, is meant to sag so you can lie across it on a diagonal. A spreader-bar hammock holds its bed open with bars and hangs flatter. Hansen's calculator recommends 20 to 30 degrees for gathered-end hammocks ("Nylon hammocks, Mayan hammocks, and most camping hammocks") and 15 to 20 degrees for spreader-bar and bridge hammocks.

Pawleys Island's chart for 11 to 14 ft (3.4 to 4.3 m) rope hammocks drops the hooks 12 in (30 cm) for every foot of span, from 108 in (2.74 m) down to a floor of 48 in (122 cm), and shades as "not recommended" any hammock 2 ft or more longer than its span. That floor is what the V gives at 20 degrees on a 14 ft (4.27 m) span with an 18 in seat. At its 450 lb (204 kg) limit, hung at 15 degrees, a rope hammock pulls 869 lbf (394 kgf) on each hook, more than four times what halving the weight suggests.

Two posts in the ground, or a pergola: the pull at 5 ft#

A tree resists through its roots; a post through its footing. The horizontal part of the strap force, applied at the hook, levers the post over with a moment of horizontal pull x hook height at ground level.

The spreader-bar hook is lower, but its flatter angle more than makes up for it. These are static figures for whoever sizes the post and footing; this page does not size them. Pawleys Island asks for wooden anchors "at least 6 inches (15 centimeters) in diameter" and, for anything else, says to "consult a building professional".

Between two posts of a pergola the two pulls point at each other and the beam joining the post tops props them apart, so each post bends between footing and beam rather than leaning over as a free cantilever. At the 8 ft (2.44 m) clear height in pergola dimensions and heights the beam sits about 3 ft (0.9 m) above a 5 ft hook, and the posts must still be 10 ft (3.05 m) apart for a gathered-end hammock, 14 ft (4.27 m) for a spreader bar. From one pergola post to a tree or the house nothing balances the pull: 173 lbf (79 kgf) for one adult goes sideways into the frame and its bracing.

Trees, walls and decks: what moves the numbers#

• Trees. ENO wants trees "at least 6 inches in diameter"; Trek Light says one hammock per tree, on wide straps rather than bare rope.
• Walls and ceilings. "Drywall absolutely does not count as an anchor", in Trek Light's words: eye bolts go into studs, joists or solid beams. A joist that already carries a bag, as in heavy bag ceiling height and space, takes the hammock's load on top.
• The user. Load scales with weight and nothing else. Sit height moves every hook inch for inch: a 20 in (51 cm) seat needs hooks 2 in (5 cm) higher, not a different span.
• Decks. Heights are measured from the boards. A deck's posts belong to its frame and guard, sized as deck sizes, railing heights and baluster spacing sets out, so check one against the post table before tying to it. On a balcony, where a 10 ft (3.05 m) span rarely exists, a stand is the usual answer.

Where these figures stop applying#

The loads are statics for a still, centred sitter on a symmetric hang. Hansen's calculator "does not take into consideration any dynamic load factors", and no source fetched for this page gives one, so dropping in and swinging add an unknown amount: treat the tables as the floor of what an anchor sees. The V ignores fabric stretch, so set hooks a little high and adjust. Stands carry their makers' ratings.

Metric figures are conversions, as imperial and metric dimension systems explains; the unit converter handles the rest. Sources are indexed in standards and codes, terms in the glossary. A fixed lounger is sized in outdoor sofa and lounger dimensions, and fitting a hammock beside a table and a route is a job for patio sizes and layouts. Keep it clear of a swing set's zone in swing set clearance and yard size and of the ring round a fire in fire pit clearances and seating. Never sling one across a garden path, and peg the span out first, as taping out a layout at full size describes.