Calculator Inputs
Example Data Table
| Garden Use Case | Length | Density | Voltage | Brightness | Input Power | Current | Suggested Supply |
|---|---|---|---|---|---|---|---|
| Seedling shelf | 2 m × 2 strips | 14.4 W/m | 12 V | 80% | ≈ 51.2 W | ≈ 4.27 A | ≥ 62 W |
| Propagation rack | 3 m × 3 strips | 10 W/m | 24 V | 100% | ≈ 100.0 W | ≈ 4.17 A | ≥ 120 W |
| Greenhouse bench | 5 m × 1 strip | 18 W/m | 24 V | 60% | ≈ 60.0 W | ≈ 2.50 A | ≥ 72 W |
Formula Used
- TotalLength(m) = LengthEach(m) × Strips
- P_full(W) = PowerPerMeter × TotalLength
- P_led(W) = P_full × (Brightness% / 100)
- P_in(W) = P_led / Efficiency
- I(A) = P_in / Voltage
- PSU(W) = P_in × (1 + Headroom% / 100)
- kWh/day = (P_in × RuntimeHours) / 1000
- Fuse(A) ≈ 1.25 × I (rounded to common sizes)
- V_drop = I × R_total
- R_total = R_per_meter × (2 × OneWayLength)
- Drop% = (V_drop / Voltage) × 100
How to Use This Calculator
- Enter strip length and how many strips you will power.
- Use the strip label to fill power per length.
- Pick your supply voltage and expected dimming level.
- Set driver efficiency and headroom for reliable operation.
- Add wire length to estimate voltage drop and gauge.
- Press Calculate to view results and download exports.
Power planning for grow shelves
LED strips used for seedlings are often run long hours, so power planning matters. This calculator converts strip length and rated watts per meter into input power after dimming and driver losses. It helps you avoid undersized supplies that overheat or flicker in humid greenhouse conditions. When selecting strips, confirm the stated power matches your chosen color temperature and channel mix. Use aluminum channels to manage heat and protect strips.
Selecting voltage and supply margin
Higher voltage systems reduce current for the same wattage, which lowers connector heating and improves distribution across multiple benches. Use the headroom field to add a practical buffer for warm environments and future expansion. A 15–30% margin is common when strips run near full output.
Understanding current and fuse guidance
Current drives wire size, connector ratings, and protection choices. The calculator estimates supply current from input watts and voltage, then suggests a fuse near 125% of operating current. In garden builds, place protection close to the power source and keep polarity labeling clear for quick service. If you power several runs, consider one fuse per branch so a single fault does not darken the entire shelf.
Voltage drop and wiring discipline
Long cable runs can dim strips and shift color temperature. Enter one-way distance and a wire gauge to estimate drop, and compare it to your allowed percent. If the recommended gauge looks heavy, consider shorter runs, thicker conductors, or higher voltage distribution with local regulators. For very long strips, inject power at both ends or at intervals to keep brightness uniform across the canopy.
Energy budgeting for controlled environments
For propagation rooms, daily energy is as important as peak power. Runtime and electricity cost estimates support budget forecasts and scheduling. Pair results with timers and sensors to reduce photoperiod waste. Document each zone’s length, density, and voltage so replacements match performance. Tracking watts per square meter also helps you compare lighting upgrades against yield, heat load, and ventilation capacity.
FAQs
What power density should I enter?
Use the manufacturer’s watts per meter or watts per foot rating for your exact strip type. If you have a 5 m reel rating, divide total watts by length to get an accurate value.
Does dimming reduce power linearly?
For many PWM dimmers, average power roughly follows the brightness percentage. Real results can vary with driver design, so treat it as a planning estimate and verify with a meter for critical installs.
How much headroom is reasonable for garden lighting?
For continuous daily operation, 15–30% headroom is typical. Choose more if your enclosure is warm, ventilation is limited, or you plan to add extra strip length later.
Why does voltage drop matter with LED strips?
Voltage drop reduces available voltage at the strip, which can dim output, shift color, and stress controllers. Keeping drop within 2–5% usually improves uniformity across shelves and benches.
Should I fuse each strip run?
If you have multiple parallel runs, fusing each branch helps isolate faults and simplifies troubleshooting. Place the fuse near the supply, and match ratings to wire capacity and expected operating current.
Can I estimate daily electricity cost here?
Yes. Enter runtime hours and your local cost per kWh. The tool estimates daily energy from input power, which is more realistic than LED-only watts because it includes driver efficiency.