How to calculate the correct transformer for your bendable LED strip installation — covering power supplies from 30W to 300W
1. About 6W/m Bendable LED Strip
Bendable LED strip — sometimes referred to as flexible neon strip, silicone flex strip, or 360° bendable strip — is a specialised form of LED strip designed to flex, curve, and bend in multiple directions without cracking or breaking. Unlike standard LED strip which bends only in a single plane, bendable strip can follow complex curves, rounded edges, letter profiles, and irregular architectural shapes.
The 6W per metre specification positions this strip as a low-to-medium power density product — lower wattage than the 9.6W/m standard strip, which reflects its construction. Bendable strips typically use fewer or smaller LEDs per metre to allow flexibility, resulting in a softer, more diffused glow that suits decorative and accent lighting applications particularly well.
Common applications for 6W/m bendable strip include illuminated signage outlines, curved architectural features, furniture edge lighting, mirror surrounds, retail display borders, and any installation requiring the strip to follow a non-linear path.
Bendable strip is available in 12V DC and 24V DC versions. The same power supply sizing principles apply to both — only the current draw differs.
2. The Basic Calculation Formula
Because the wattage per metre is fixed at 6W, calculating the power requirement for any installation is straightforward:
Total Wattage = Total Metres × 6W
Minimum Power Supply Size = Total Wattage ÷ 0.8 (80% load safety rule)
The 80% rule is essential and must always be applied. Running a transformer at its full rated capacity continuously causes it to run hot, reduces its lifespan significantly, and increases the risk of premature failure. By keeping the load to 80% of the transformer’s rated output, you ensure reliable long-term operation and a buffer for any minor load variations.
⚠ IMPORTANT: A transformer loaded beyond 80% of its rated capacity will run hot to the touch, shorten its service life, and is far more likely to fail. Always apply the 80% rule — it is a fundamental requirement, not a suggestion.
3. Step-by-Step Worked Examples
Example 1: Mirror Surround — 3 Metres
Step 1: Calculate total wattage → 3m × 6W = 18W total
Step 2: Apply 80% rule → 18W ÷ 0.8 = 22.5W minimum transformer
Step 3: Select next standard size above 22.5W → 30W
Result: A 30W transformer is the correct selection for 3 metres of 6W/m bendable strip.
Example 2: Retail Display Border — 8 Metres
Step 1: Calculate total wattage → 8m × 6W = 48W total
Step 2: Apply 80% rule → 48W ÷ 0.8 = 60W minimum transformer
Result: A 60W transformer is the exact minimum. Select a 75W or 100W for greater headroom and reliability.
Example 3: Curved Architectural Feature — 16 Metres
Step 1: Calculate total wattage → 16m × 6W = 96W total
Step 2: Apply 80% rule → 96W ÷ 0.8 = 120W minimum transformer
Step 3: Select next standard size → 120W or 150W
Result: Use a 150W transformer for comfortable headroom, or split across two 75W or 100W units feeding two 8m runs.
Example 4: Large Illuminated Sign Outline — 30 Metres
Step 1: Calculate total wattage → 30m × 6W = 180W total
Step 2: Apply 80% rule → 180W ÷ 0.8 = 225W minimum transformer
Step 3: Select next standard size → 250W or 300W
Result: Use a 250W or 300W transformer, or split across two 150W units each serving 15m runs. Splitting is preferred for voltage drop management on 12V installations.
✔ TIP: When an installation sits between two transformer sizes, always select the larger. The cost difference between a 150W and 200W transformer is minimal — the performance and reliability benefit is significant.
4. Quick Reference: Metres Per Transformer
The table below shows the maximum metres of 6W/m bendable LED strip that can safely be powered by each standard transformer size, with the 20% safety headroom already factored in.
| Transformer | Max Load (80%) | Max Metres | 12V Current | 24V Current | Typical Application |
| 30W | 24W | 4.0m | 2.0A | 1.0A | Mirror surrounds, small accents |
| 40W | 32W | 5.3m | 2.7A | 1.3A | Small display borders |
| 60W | 48W | 8.0m | 4.0A | 2.0A | Medium retail displays |
| 75W | 60W | 10.0m | 5.0A | 2.5A | Feature lighting, signage |
| 100W | 80W | 13.3m | 6.7A | 3.3A | Cove, curved features |
| 120W | 96W | 16.0m | 8.0A | 4.0A | Architectural features |
| 150W | 120W | 20.0m | 10.0A | 5.0A | Larger sign outlines |
| 200W | 160W | 26.7m | 13.3A | 6.7A | Commercial signage |
| 250W | 200W | 33.3m | 16.7A | 8.3A | Large architectural |
| 300W | 240W | 40.0m | 20.0A | 10.0A | Large signs, facades |
Note: Current values are for the DC output side of the transformer. 12V installations carry double the current of equivalent 24V systems. Size output cabling accordingly — refer to The Lighting Zone Wire Gauge Selection Guide.
5. Bendable Strip vs Standard Strip: Key Differences
Installers moving from standard LED strip to bendable strip should be aware of several important differences that affect both the installation method and power supply selection.
| Factor | Standard LED Strip (9.6W/m) | Bendable Strip (6W/m) |
| Power density | 9.6W per metre | 6W per metre |
| Flexibility | Single plane bend only | Multi-directional flex |
| Construction | Flat PCB with exposed LEDs | Silicone or resin encased |
| Light output | Higher brightness | Softer, more diffused glow |
| Cut points | Every 3 or 6 LEDs | Per manufacturer spec — check data sheet |
| Best for | Straight runs, coves, cabinets | Curves, outlines, letters, shapes |
| Transformer sizing | Metres × 9.6W ÷ 0.8 | Metres × 6W ÷ 0.8 |
6. 12V vs 24V: Choosing the Right Voltage
As with all LED strip, 6W/m bendable strip is available in both 12V and 24V versions. For the same wattage, a 24V system draws half the current of a 12V system — meaning lighter cable, less voltage drop, and longer possible runs from a single feed point.
• 12V bendable strip draws 0.5A per metre at 6W/m. Maximum recommended run length is 5 metres per feed point before voltage drop becomes visible.
• 24V bendable strip draws 0.25A per metre at 6W/m. Maximum recommended run length extends to 10 metres per feed point.
✔ TIP: For sign outlines and curved installations where the strip must travel a long continuous path, 24V is strongly recommended. The lower current draw allows the full outline to be powered from fewer feed points with consistent brightness throughout.
7. Voltage Drop on Curved and Outline Installations
Bendable strip is frequently used to outline letters, shapes, and curved features — meaning the strip may travel a considerable total distance even though the physical area of the sign appears modest. A single letter outline can easily use 1.5 to 3 metres of strip, and a full sign face with multiple letters can reach 20 metres or more of total strip length.
In these installations, voltage drop management is critical to achieving uniform brightness across the entire outline. Key practices include:
• Feed at multiple points along the outline rather than from a single entry point.
• Keep individual runs short — plan the routing of the strip so no single continuous run exceeds the recommended maximum length.
• Use adequately sized feed cable between transformer and strip — refer to The Lighting Zone Wire Gauge Selection Guide for cable sizing.
⚠ IMPORTANT: On letter outline and sign installations, always plan your feed points before beginning installation. Retrofitting additional feed points after the sign is assembled is difficult and often impossible without dismantling the sign face.
8. When to Use Multiple Transformers
For larger installations or where a single transformer would be loaded close to its 80% limit, splitting across two or more transformers is recommended. This is especially relevant for bendable strip sign installations where:
• The total strip length exceeds 20 metres.
• The sign has multiple sections or letter groups that can logically be powered independently.
• The transformer needs to be concealed within a sign cabinet where heat dissipation is limited.
• Redundancy is required — for instance, on externally illuminated commercial signage where a transformer failure would leave the sign dark.
As a practical guideline, for total bendable strip installations above 20 metres, use two or more transformers. Position each transformer as close as possible to the section of strip it powers to minimise output cable length and voltage drop.
9. Summary: The 3-Step Method
Use these three steps for every 6W/m bendable LED strip installation:
Step 1 — Measure total strip length in metres and multiply by 6W to get total wattage.
Step 2 — Divide total wattage by 0.8 to determine the minimum transformer size required.
Step 3 — Select the next available standard transformer size at or above the minimum. For runs over 10 metres, consider 24V strip and multiple feed points or transformers.
10. Need Assistance?
For help sizing power supplies, planning bendable strip installations, or selecting the right products for your project, please contact The Lighting Zone: