MR16 Beam Angles: Spot vs. Flood and Coverage Chart
Choose an MR16 beam angle by the width of the feature and the distance from the lamp to that feature. Narrow beams suit concentrated accents; wider beams cover broader areas. A 30° beam is approximately 5.4 feet wide at 10 feet, but only 2.7 feet wide at 5 feet.
The right beam can improve a landscape lighting scene more than adding wattage. Start with coverage, then check whether the lamp delivers enough light to the surface.
What is an MR16 beam angle?
Beam angle describes the spread of a directional lamp. The Illuminating Engineering Society defines it using the directions where luminous intensity falls to half of the maximum. The light does not stop at that boundary: spill can extend beyond it, and the beam is not necessarily evenly bright.
That distinction matters near windows, property lines and paths. A lamp's nominal beam circle is a planning tool, not a guarantee that all light stays inside it.
Spot vs. flood: which should you choose?
| Example angle | Effect to test | Watch for |
|---|---|---|
| 10°–15° | Concentrated accent on a slender feature or distant detail | Bright hot spots and missed branches |
| 24°–40° | Moderate coverage for a smaller tree, shrub or architectural feature | Whether the beam reaches the edges at the actual distance |
| 60° | Broader coverage across planting or a wider surface | Spill and reduced concentration compared with a narrow beam |
| 100°–120° | Very broad coverage at close range | Glare, off-target light and fixture restrictions |
Manufacturers use “spot,” “flood” and “wide flood” differently. Compare the degree value and photometric distribution rather than assuming two lamps marked “flood” produce the same result. These ranges are design starting points; the target and viewing conditions decide the final choice.
MR16 beam coverage chart
The table estimates a circular beam on a flat surface perpendicular to the beam's centerline. Distance means the distance along that centerline to the target, not simply how far the stake sits from a tree trunk.
| Beam angle | At 5 ft | At 10 ft | At 15 ft |
|---|---|---|---|
| 15° | 1.3 ft | 2.6 ft | 3.9 ft |
| 24° | 2.1 ft | 4.3 ft | 6.4 ft |
| 30° | 2.7 ft | 5.4 ft | 8.0 ft |
| 36° | 3.2 ft | 6.5 ft | 9.7 ft |
| 40° | 3.6 ft | 7.3 ft | 10.9 ft |
| 60° | 5.8 ft | 11.5 ft | 17.3 ft |
Calculation: beam diameter = 2 × distance × tan(beam angle ÷ 2). Use the same units for diameter and distance and calculate the tangent in degrees. These are geometric estimates, not measured photometric results.
For an angled wall or irregular canopy, the pattern changes. Branches create shadows, leaves interrupt the beam and an oblique surface stretches the footprint. Use an on-site test or the lamp's photometric file to refine the design.
A worked example: lighting a six-foot-wide feature
Suppose the center of the feature is 10 feet from the lamp and the section you want to light is roughly 6 feet wide. The approximate angle required is 2 × arctan(6 ÷ 20), or 33.4°. A 36° lamp is a reasonable first sample. A 15° beam would cover only about 2.6 feet at that distance, so a higher lumen rating would not fix the missing width.
Now move the lamp closer, to 5 feet from the same target plane. A 36° beam covers about 3.2 feet. You would need a wider beam or a different placement. This is why selecting a lamp solely from a tree's height or width often disappoints.
Why equal lumens do not mean equal punch
Lumens describe total output. For similar optical designs, concentrating that output into a narrower beam generally increases intensity near the center. The wider lamp may light more of the scene while appearing less intense on one small detail.
When available, compare center-beam candlepower and illuminance data at the intended distance. Do not assume a lower-lumen narrow beam is weaker on the target than a higher-lumen wide beam.
Fine-tune the result after dark
- Choose the feature and the main viewing position.
- Estimate distance and required coverage using the chart.
- Test one appropriate beam at a modest output.
- Check the feature's edges, shadows and nearby windows.
- Adjust position or beam before increasing output.
- Check again from the path and seated eye level for direct glare.
Use only manufacturer-approved lenses or optical accessories. A field-changeable lens is convenient, but it does not remove the need to confirm lamp fit, output and the fixture's restrictions. For placement ideas, see our landscape uplighting guide.
Frequently asked questions
What is the best MR16 beam angle for a tree?
There is no single angle for every tree. Measure the portion you want to emphasize and the distance to it, then test coverage. A narrow trunk accent and a broad canopy wash can require different beams.
Does a wider beam use more electricity?
Beam angle alone does not determine power consumption. Compare the wattage of the exact lamps.
Will a spot lamp stop light spill?
No. It concentrates the main beam, but spill and direct glare can remain. Placement, aiming and suitable shielding also matter.
Shop MR16 lamps by beam angle, or use our MR16 replacement guide to check base and electrical compatibility.
- Atlantic Lighting