Privacy Screen Height Calculator
Enter where the view comes from, where your private area is and where the screen would stand. The calculator draws the sightlines and gives the minimum height, the recommended height with margin, and the width needed.
What to measure
The calculator needs five numbers. None of them needs millimeter accuracy, but each one matters.
| Measurement | How to get it |
|---|---|
| Observer eye height | For a person on the ground, about 1.6 m (5 ft 3 in) to 1.75 m (5 ft 9 in). For a window, estimate the floor level and add eye height: a typical house story is roughly 2.7–3.2 m (9–10 ft 6 in). Counting brick courses (about 75 mm each in the UK, about 67 mm or 2⅝ in in the US) or siding boards gives a better estimate than guessing. |
| Distance to the private area | Horizontal distance from the window wall to the nearest edge of your patio or seating. A long tape or laser measure is ideal; a property plan works too. |
| Distance to the screen | Where the screen could realistically stand, measured from the same starting point. |
| Height to hide | Seated adults ≈ 1.2 m (4 ft); reclining ≈ 0.9 m (3 ft); standing ≈ 1.8 m (6 ft); a pool surface or lawn = 0. |
| Safety margin | Extra height above the calculated minimum. 10–30 cm (4–12 in) is typical. |
Measure everything from the same ground level. If your yard slopes, or the patio sits on a raised deck, switch to Advanced mode and enter the elevations; otherwise the result will be off by exactly the height difference.
The formula, step by step
A sightline is a straight line, so the height needed at the screen follows from similar triangles. Take the planner’s example: a second-floor window with eyes at 4.60 m (15 ft 1 in), a patio whose far edge is 13 m away, seated heads at 1.20 m (3 ft 11 in), and a screen 7.5 m from the window.
- Total drop of the sightline: 4.6 − 1.2 = 3.4 m over 13 m.
- The screen stands 7.5 / 13 = 0.577 of the way along.
- By then the line has dropped 3.4 × 0.577 = 1.96 m.
- Crossing height: 4.6 − 1.96 = 2.64 m. With a 20 cm margin: 2.84 m.
height at screen = eye height + (height to hide − eye height) × (screen distance ÷ target distance)
With several observers or a wide area, the calculator repeats this for every viewpoint and every corner of the area and keeps the largest value. That is why the result can be higher than a quick single-line estimate.
How position changes the height
The same example, evaluated at different screen distances (including the 20 cm margin, a 4.5 m wide patio and a 1.2 m wide window):
| Screen distance from window | Height needed | Width needed | Screen area |
|---|---|---|---|
| 4.00 m (13 ft 1 in) | 3.76 m (12 ft 4 in) | 2.67 m (8 ft 9 in) | 10.0 m² |
| 5.50 m (18 ft 1 in) | 3.37 m (11 ft 1 in) | 3.22 m (10 ft 7 in) | 10.8 m² |
| 7.00 m (23 ft 0 in) | 2.97 m (9 ft 9 in) | 3.77 m (12 ft 5 in) | 11.2 m² |
| 7.50 m (24 ft 7 in) | 2.84 m (9 ft 4 in) | 3.95 m (13 ft 0 in) | 11.2 m² |
| 8.50 m (27 ft 11 in) | 2.58 m (8 ft 6 in) | 4.32 m (14 ft 2 in) | 11.1 m² |
| 8.90 m (29 ft 2 in) | 2.48 m (8 ft 2 in) | 4.47 m (14 ft 8 in) | 11.0 m² |
Moving the screen from 4 m to 8.9 m lowers the height by 1.28 m but widens it by 1.80 m. Which is better depends on what you can build: see privacy screen placement, or use the distance calculator if you already know the height of the screen you want.
Rounding and precision
The calculator keeps full precision internally and rounds required values up to the displayed step (1 cm or 1 in), so applying a displayed number never leaves you short. It does not show results such as “1.873928 m” because no garden measurement supports that precision. Result accuracy depends on your measurements.
Common mistakes
- Measuring the window instead of the eyes. Someone standing at a window has eyes well above the sill. The planner keeps the viewpoint within the window opening in Advanced mode.
- Forgetting elevation. A patio 40 cm above the lawn or a neighbor’s house on higher ground changes every number.
- Hiding the wrong height. Hiding people seated at a table needs far less than hiding people standing at a barbecue.
- Ignoring width. A screen tall enough but too narrow is seen around. The top view shows the outermost sightlines.
- Treating geometry as permission. A geometrically required height says nothing about what is allowed locally. Check local rules before building.
Frequently asked questions
What is the difference between minimum and recommended height?
The minimum is the exact height at which the highest sightline crosses the screen position. The recommended height adds your safety margin on top, to allow for taller viewers, viewers standing on a step, and small measuring errors. Build to the recommended height, not the minimum.
Why does the calculator use the far edge of my patio?
When the viewer is higher than what you are hiding, the sightline to the far edge is the flattest one, so it crosses any screen in between at the greatest height. If the viewer is lower than what you are hiding — for example looking up at a raised deck — the near edge becomes the limiting point instead. The planner checks both automatically and tells you which one governs.
Does the calculator include the gap under a screen or lattice gaps?
No. It assumes an opaque barrier from the ground (or the base elevation you enter) up to its top. If a screen panel is mounted above a gap, or has open slats or lattice, the effective blocking height and opacity are lower than the panel’s nominal size.
How accurate is the result?
The geometry is exact for the numbers entered, but the result can only be as accurate as your measurements. Errors in the viewer’s height matter most when the screen is far from your seating area. Checking on site with a pole of the proposed height and a helper at the window is worthwhile before you build.
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