LED Grow Panel Light: 120W, 160W, or 240W — Which Size Do You Need?
The most common sizing mistake in indoor growing is buying by wattage instead of by footprint. A 240W panel isn’t “better” than a 120W — it’s bigger, and it only pays off if you have the tent to spread it across. Here’s how to match panel power to grow space for seedling, veg, and flower stages.
The coverage table
| Panel power | Best footprint (veg) | Footprint (flower) | Typical PPFD @ 18 in |
|---|---|---|---|
| 120W | 2 × 2 ft | 1.5 × 1.5 ft | 400–550 µmol/m²/s |
| 160W | 2 × 4 ft | 2 × 2 ft | 400–550 µmol/m²/s |
| 240W | 4 × 4 ft | 2 × 4 ft | 400–600 µmol/m²/s |
The pattern: flowering needs roughly twice the photons of veg per square foot, so the same fixture covers about half the area in flower. If you want to run flower in a 4 × 4 ft tent, that’s a 400–500W class light — 240W covers 4 × 4 ft for veg and the center of the tent for flower.
Matching power to your stage
- Seedling stage: small plants, low light needs (150–250 µmol/m²/s). A 120W panel at 24 inches covers a generous seedling area — this is where small panels shine and big ones are wasted.
- Vegetative stage: 400–600 µmol/m²/s is the working range. Use the veg column of the table above.
- Flowering stage: fruiting plants want 600–900 µmol/m²/s. Plan for the flower footprint when you buy — it’s the expensive direction.
Rules of thumb
- Measure your tent, not your ambitions. A 4 × 4 ft tent with a 120W light is a common under-powering mistake. Match the panel to the floor area.
- Double the wattage for flower. If you want flower in the same space you veg in, budget for roughly 2× the fixture power or accept a smaller flower footprint.
- Dimmable beats single-wattage. A 120W dimmable panel can run at 30% for seedlings and 100% for bloom — one fixture, multiple stages.
- Check the PPFD map. Two “100W” fixtures can differ by 30% in real canopy intensity. Compare measured PPFD, not nominal wattage.
Which panel is right for you?
- 2 × 2 ft tent, all stages: 120W dimmable — our 120W spider with UV switch is the natural fit.
- 2 × 4 ft tent, veg-heavy: 160W class panel.
- 4 × 4 ft tent, veg only: 240W panel; for flowering, step up or run a smaller flower footprint.
- Seed trays and shelves: you likely need much less — see how many watts desktop plants need and the 45W guide.
The one-line version
Pick the panel by measuring your grow footprint first, decide veg vs. flower second, and let a dimmer cover the rest. 120W → 2 × 2 ft, 160W → 2 × 4 ft, 240W → 4 × 4 ft veg.
GoldenBuds builds panels across the 120–240W range with full PPFD test data on file. Browse products or contact us for a sizing recommendation for your exact tent.