Halloween fog hose run length
Estimate duct hose feet from a fog machine to a yard effect, including vertical rise and spare for chillers — a haunt planner for Prince William County Halloween setups.
hose_ft = horizontal_ft + rise_ft × rise_factor + spare_ft
When to use
Use this when piping fog from a hidden machine to a tombstone, cauldron, or window well with flexible duct hose.
Rise factor (>1) adds length for friction and condensation on upward runs — many haunters start around 1.2–1.5× vertical feet.
Complements fog runtime and low-lying ice-mix tools: those size fluid and ice; this sizes the hose path.
Machine to effect along the ground path.
Up into a window, loft, or raised prop.
1.0 = flat add; 1.3–1.5 common for upward ducting.
Slack for hiding hose and chiller loops.
Worked example
Example defaults — Horizontal 12 ft; Rise 3 ft; Factor 1.3; Spare 3.
Compute: hose = 12 + 3 × 1.3 + 3 = 12 + 3.9 + 3 = 18.9 ft → buy a 20 ft section or two shorter couplers.
Prefer 4-inch duct over skinny hose so fog does not condense into sludge halfway.
Second example: one input changed
From the defaults (Horizontal run (feet) = 12; Vertical rise (feet) = 3; Rise factor = 1.3; Spare / dressing (feet) = 3), the calculator shows:
Hose needed: 18.9 ft
Buy at least: 19 ft (rounded up)
Rise contribution: 3.9 ft.
Now raise Horizontal run (feet) from 12 to 18 and keep the other entries. The result becomes:
Hose needed: 24.9 ft
Buy at least: 25 ft (rounded up)
Comparing the two runs tells you how sensitive the answer is to that one measurement. If a small change in it swings the result a lot, measure it twice.
Limits / assumptions
Units: distances in feet; rise factor unitless.
Assumptions: single hose path; no branch tees; machine can push the estimated length.
Not a substitute: manufacturer max duct length or fire-code rules for indoor fog.
Leave an air gap at the machine nozzle so the unit does not overheat. Never duct fog into occupied sleeping rooms without ventilation planning.
FAQ
How long is too long?
Many consumer machines struggle past ~25–30 ft of small duct — test a short run first.
Low-lying fog?
Route through a chiller/ice chest; add spare feet for the chiller loop.
Fluid runtime?
Use fog machine runtime and low-lying mix tools for juice and ice.
Underground trench?
Count trench length as horizontal; waterproof connections.