Hammock Hang Calculator — Strap Length, Sag & Tension
Set up your hammock perfectly: enter the tree (anchor) distance, desired sag angle and your weight to get the ideal strap length, sag depth, required hammock body length and the tension each strap must handle.
Units
m
°
kg
Force each strap must support — lower angle = higher tension
- 1
Sag angle in radians
30° × π ÷ 180 = 0.523599 - 2
sin(θ)
sin(0.5236) = 0.5At 30° sin(θ) = 0.5, so each strap must carry exactly the full body weight — the 30° design rule - 3
Strap tension per side = (weight ÷ 2) ÷ sin(θ)
(80 ÷ 2) ÷ 0.5 = 80
How does this calculator work?
At sag angle θ between anchors D apart: each strap = (D/2)/cos θ, sag depth = (D/2)·tan θ, and each strap tension = (W/2)/sin θ. The 30° rule keeps tension equal to body weight and is the standard camping recommendation. Hammock body ≈ 90% of the suspension chord.
Formula
How this is calculated
A hammock hangs as a catenary curve, but for practical rigging the simple triangle model is accurate enough: each suspension strap forms the hypotenuse of a right triangle whose horizontal leg is half the anchor spacing (D/2) and whose angle below horizontal is the sag angle θ. From this triangle, sag depth = (D/2)·tan θ and strap length = (D/2) / cos θ.
The critical result is strap tension. Because each strap must support half the occupant weight at angle θ, the tension = (W/2) / sin θ. This grows rapidly as θ shrinks: at 30° each strap carries exactly the full body weight; at 10° each strap carries nearly three times the body weight — which can snap budget straps and damage tree bark. The 30° rule (a 30° angle below horizontal) is the widely recommended camping standard that balances comfort and strap load.
The recommended hammock body length is approximately 90% of the full suspension chord length (D / cos θ), since hammock fabric is gathered at the ends and stretched diagonally, not end-to-end. Minimum anchor height above ground equals sag depth plus about 0.5 m clearance under the hammock.
Frequently asked questions
At exactly 30° each strap carries a force equal to the full occupant weight — manageable for most tree straps and hardware. Below 30° tension rises steeply (e.g. 10° = ~2.9× body weight), risking equipment failure and bark damage. Above 30° the hammock sits too flat to be comfortable and may not cradle you correctly.
Add at least 0.5–1 m of extra strap beyond the calculated length to wrap around tree trunks and adjust for different anchor heights. Most campers carry 3 m straps per side, which covers spans of 3–5 m at 30°.
Adjust the sag angle: closer trees need a steeper angle (more sag, lower tension) and farther trees a shallower angle. Never go below 15° as strap forces become extreme, and avoid angles above 45° as the hammock becomes uncomfortably hammock-banana-shaped.
Also known as
TG we-Calculate Editorial Team. (2026). Hammock Hang Calculator — Strap Length, Sag & Tension [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/hammock-hang-calculator
TG we-Calculate Editorial Team. "Hammock Hang Calculator — Strap Length, Sag & Tension." TG we-Calculate. 2026. https://we-calculate.com/calculator/hammock-hang-calculator.
TG we-Calculate Editorial Team, "Hammock Hang Calculator — Strap Length, Sag & Tension," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/hammock-hang-calculator
@misc{wecalculate_hammock_hang_calculator, title = {Hammock Hang Calculator — Strap Length, Sag & Tension}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/hammock-hang-calculator}}, year = {2026}, note = {TG we-Calculate} }
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