Introduction
Choosing the right grow light for your tent size is the main factor that determines how well your plants grow indoors. A 2×2 tent only needs around 100–150 W of real LED power, while a 4×4 or 5×5 setup performs best with 400–800 W and far stronger PPFD. Pick the wrong fixture and you’ll see weak growth, stretching, poor yields and uneven canopy lighting.
This guide shows you exactly which grow light matches each tent size, from compact 60×60 cm tents to large 300×300 cm grow rooms. The comparison chart and recommendations below make it simple to choose the correct wattage, PPFD and fixture layout the first time.
For a broader overview of grow light types, setup, and indoor use, see our Grow Lights UK complete guide, which also links out to more detailed deep-dive articles on topics like light spectrum, distance, and timing.
If you’re still choosing your tent, you may also want to explore our Grow Tents UK hub for size guides, setup tips and compatible accessories
Affiliate notice: Some links are affiliate links. As an Amazon Associate, HomeGrower may earn from qualifying purchases at no extra cost to you.
Grow Light Coverage & Wattage Chart
| Grow Tent / Room Size | Approx. Area | Example Fixture | Total LED Power (W) | Actual Wattage Draw (W real) | Target PPFD (µmol·m−2·s−1) | PPFD @ 30 cm | Typical UK Price | Notes |
|---|---|---|---|---|---|---|---|---|
| 2 × 2 ft (60 × 60 cm) | 0.37 m² | Spider Farmer SF1000 | 100–150 W | ~100 W | 400–600 | ~500 | £90–£140 | Ideal for seedlings, herbs and leafy greens; low heat and very efficient. |
| 3 × 3 ft (90 × 90 cm) | 0.84 m² | AC Infinity IONBoard S22 | 200–300 W | ~200–240 W | 600–900 | ~700 | £110–£160 | Great for 2–4 compact plants; excellent heat control and uniformity. |
| 4 × 4 ft (120 × 120 cm) | 1.44 m² | Mars Hydro FC-E4800 | 400–600 W | ~450 W | 900–1000 | ~1000 | £450–£600 | Strong bar-style coverage; excellent PPFD and value for 4×4 full-cycle grows. |
| 5 × 5 ft (150 × 150 cm) | 2.25 m² | AC Infinity IONBoard S44 | 600–800 W | ~650–720 W | ≈1000 | ~1100 | £300–£370 | Performs best with good airflow (≥8″ extraction); strong penetration for dense canopies. |
| 8 × 4 ft (240 × 120 cm) | 2.88 m² | Spider Farmer SE3000 (×2) | 600–800 W | ~300–350 W per light | 900–1000 | ~900 per light | £250–£350 each | Run two fixtures side-by-side for even light spread with 10–20% overlap. |
| 10 × 5 ft (300 × 150 cm) | 4.50 m² | Mars Hydro FC-E4800 (×2) | 800–1200 W | ~480–500 W per light | 900–1000 | ~950 | £450–£600 each | Two units give strong veg coverage; add a third for dense flowering crops. |
| 12 × 8 ft (360 × 240 cm) | 8.64 m² | Spider Farmer SE5000 (×2) | 1300–1800 W | ~480–500 W per light | 900–1000 | ~1000 | £350–£550 each | Arrange in a 2×2 grid for balanced PPFD across very large canopies. |
| 10 × 10 ft (300 × 300 cm) | 9.00 m² | Spider Farmer SE7000 (×2) | 1600–2400 W | ~650–700 W per light | 900–1000 | ~1100 | £500–£800 each | Two fixtures provide full tent coverage with deep canopy penetration. |
| 20 × 10 ft (600 × 300 cm) | 18.0 m² | Mars Hydro FC-E8000 | 2400–3200 W | ~820–900 W | 900–1000 | ~1200 | £450–£600 | Good for commercial layouts; adjustable bars and strong extraction strongly recommended. |
| 30 × 15 ft (900 × 450 cm) | 41.9 m² | AC Infinity IONFrame EVO8 | 4800–6400 W | Varies by zone | 900–1000 | ~1100–1200 | £750–£950 | Divide into lighting zones on separate timers for optimal performance and maintenance. |
Choosing the Best Grow Light for Your Tent Size
The best way to choose the right grow light for your tent size is to match the LED’s true wattage and PPFD output to the actual canopy area you’re lighting. Smaller tents like 2×2 ft and 3×3 ft perform perfectly with efficient 100–200 W LEDs, while mid-sized tents such as 4×4 ft, 5×5 ft, and 8×4 ft need significantly more intensity to maintain even coverage across the full footprint.
A good guideline is to aim for:
- 400–600 PPFD for seedlings and leafy greens
- 600–900 PPFD for general veg growth
- 900–1000+ PPFD for fruiting and flowering crops
Using the correct power level ensures:
- strong, even canopy development
- reduced stretching
- fewer hot spots
- consistent results throughout the entire growth cycle
If you’re unsure about hanging height or how to optimise intensity, see our Grow Light Distance Chart, which includes recommended heights for bulbs, bars and LED panels.
For growers setting up a new tent for the first time, our How to Set Up Grow Lights guide walks through reflective surfaces, positioning, airflow and timers.
🌱 Recommended Grow Lights for Each Tent Size (UK Guide)
⭐ 2×2 ft (60×60 cm) – Best Light → Spider Farmer SF1000
The SF1000 is ideal for a 2×2 tent because it delivers strong PPFD (around 500–600 µmol/m²/s at 30 cm) without overheating small spaces. Its Samsung-style diodes provide excellent efficiency and an even footprint, making it perfect for seedlings, herbs, salads, microgreens and low-to-medium-light edibles.
Why it’s the best for 2×2:
- Excellent uniformity across a small canopy
- Very low heat output — ideal for compact UK grow tents
- High efficiency = low running costs
- Quiet fanless design
⭐ 3×3 ft (90×90 cm) – Best Light → AC Infinity IONBoard S22
The IONBoard S22 provides an excellent balance of centre and edge PPFD, making it ideal for 3×3 growers who want efficient lighting with minimal heat. Its uniform footprint and cool operation suit 2–4 compact plants, especially in UK homes where ventilation is more limited.
Why growers love it:
- Cool, even output across the entire 3×3 footprint
- Very good PPFD for veg and light flowering crops
- High efficiency at a mid-range price
- Pairs perfectly with AC Infinity environment controllers
See our How to Set Up Grow Lights if you’re building your first tent.
🛒 See on Amazon⭐ 4×4 ft (120×120 cm) – Best Light → Mars Hydro FC3000
For a 4×4 tent, bar-style LEDs offer the best uniformity — and the Mars Hydro FC3000 is one of the strongest performers for the price. It delivers excellent PPFD (around 1000 µmol/m²/s at 30 cm), deep canopy penetration, and exceptional edge-to-edge evenness.
Why it excels in 4×4:
- Superb distribution due to modular bar layout
- Excellent PPFD for full-cycle crops
- Strong dimming control for seedlings → veg → flower
- High efficiency diodes keep heat manageable
⭐ 5×5 ft (150×150 cm) – Best Light → AC Infinity IONBoard S44
The S44 delivers high-intensity PPFD suitable for full-cycle growing in a larger tent. Its strong output and even distribution make it ideal for dense canopies, taller plants, and high-demand leafy or fruiting crops.
Why it’s a great 5×5 choice:
- Deep canopy penetration
- Very strong PPFD across the footprint
- Works extremely well with ≥8″ extraction fans
- A more affordable option than many 5×5 competitors
⭐ 8×4 ft (240×120 cm) – Best Lights → Two Spider Farmer SE3000 Units
Two SE3000 panels create excellent left-to-right and front-to-back uniformity in an 8×4 tent. The overlapping bar footprints help eliminate hotspots while maintaining strong PPFD levels across the entire canopy.
Why two SE3000s work so well:
- True uniform bar-style coverage
- Each light can be dimmed/raised independently
- Great flexibility for mixed crops or staggered growth cycles
- Ideal for veg and full-cycle edible growing
⭐ 10×5 ft (300×150 cm) – Best Lights → Two Mars Hydro FC-E4800 Units
The FC-E4800 is exceptional in long, rectangular tents. Two units give balanced coverage and strong penetration, with the option to add a third for high-density flowering or commercial-style crops.
Why it’s ideal:
- Flexible bar spacing for custom layouts
- Affordable for the output level
- Very strong PPFD along central rows
- Good heat performance for larger tents
Optional: Run a 3-light grid for maximum uniformity.
🛒 See on Amazon⭐ 12×8 ft (360×240 cm) – Best Lights → Two Spider Farmer SE5000 Units
A pair of SE5000 fixtures arranged in a 2×2 layout gives outstanding uniformity in a large, wide tent. This setup minimises shadows and supports consistent growth across wide, multi-row indoor gardens.
Why this layout wins:
- Excellent uniformity in both long and wide dimensions
- Enough intensity to support full-cycle crops
- Modular spacing options
- Bar design eliminates hotspots
⭐ 10×10 ft (300×300 cm) – Best Lights → Two Spider Farmer SE7000 Units
For growers needing very high output across a square 10×10 tent, the SE7000 is a powerhouse. Two units offer full tent coverage with impressive depth, making them ideal for taller or more demanding crops.
Why it’s top-tier:
- Deep canopy penetration
- Extremely strong PPFD for flowering crops
- Great efficiency for the wattage
- Perfect for high-intensity growing environments
⭐ 20×10 ft (600×300 cm) – Best Light → Mars Hydro FC-E8000
The FC-E8000 is the most practical solution for large-scale or commercial layouts. With adjustable bars and huge output, it’s capable of illuminating long grow beds or large tent rows evenly.
Why it’s ideal:
- Huge coverage area
- Adjustable bar layout for custom footprints
- Strong PPFD for large edible or flowering crops
- Ideal for commercial tents and high-output grows
⭐ 30×15 ft (900×450 cm) – Best Light → AC Infinity IONFrame EVO8
The EVO8 is a modular, high-output lighting system designed for very large spaces. Using multiple lighting zones allows targeted coverage, reduced waste, and easier maintenance.
Why it wins for oversized tents:
- Modular design with flexible layouts
- High, even PPFD across wide areas
- Can be run in zones on separate timers
- Ideal for large indoor food production
How to Calculate Grow Light Coverage & Power Needs
Getting your lighting power right is the foundation of healthy indoor growth. The best grow lights for every tent size deliver enough intensity to drive photosynthesis without wasting energy or creating excess heat. To balance these factors, you’ll need to size your light based on both your tent’s footprint and the real efficiency (PPFD output) of your LEDs.
Modern high-efficiency LEDs generally perform best when you supply 30–40 watts per square foot (≈320–430 W per m²) of canopy area. This usually produces 600–1,000 µmol·m⁻²·s⁻¹, a reliable range for most herbs, leafy greens, vegetables and compact flowering crops.
To calculate your lighting needs:
- Measure your tent’s footprint
Example: a 4×4 ft tent covers 16 sq ft (1.44 m²). - Multiply by 35 W (a good middle ground).
16 sq ft × 35 W = 560 W recommended total LED draw. - Match the wattage to real fixtures, such as one high-output 600 W panel or two 300 W bar-style LEDs spaced evenly across the canopy.
Because every tent size requires a different intensity level and spread, the table above provides a fast reference for wattage, PPFD targets and recommended fixtures across both single-light and multi-light layouts.
If you’re comparing LEDs, you can also explore our Grow Lights UK hub for more buying guidance across different budgets and growing methods.
How to Choose the Right Grow Light
Choosing the right grow light comes down to matching coverage, intensity, and efficiency to the size of your tent. Here are the key principles to follow:
• Match the light’s true coverage to your tent size
Manufacturers list a “flowering coverage” area — make sure it aligns with your exact tent dimensions. Undersized fixtures create dim edges and stretching; oversized ones waste energy and generate excess heat.
• Use reflective surfaces to maximise efficiency
Grow tents naturally improve PPFD by reflecting light back into the canopy. If you’re growing in an open room, use white walls or mylar sheeting to avoid losing 20–30% of usable light.
• Maintain proper hanging height
LEDs typically perform best 25–45 cm above the canopy, depending on dimming level and growth stage. Too high reduces PPFD; too low risks light stress.
For exact heights by model type, see our Grow Light Distance Chart.
• Choose high-efficiency LEDs
Look for fixtures rated 2.5–3.0 µmol/J or higher. These deliver stronger PPFD with less heat and lower running costs — essential in mid and large tents where efficiency compounds quickly.
This framework makes it easy to compare fixtures and ensures your tent receives the right combination of intensity, spread and efficiency
Multi-Light Layouts & Spacing for Large Tents
When your grow space exceeds 1.5 m (5 ft) in either direction, multiple LEDs almost always outperform a single large fixture. Using two or more lights improves uniformity, reduces edge dimming, and allows far better control over PPFD across the full canopy.
General spacing guidelines:
- Overlap light footprints by 10–20% for smooth PPFD distribution.
- Keep edge fixtures 20–30 cm (8–12 in) from tent walls to avoid wasted light.
- For long tents (e.g. 8×4 ft / 240×120 cm), space two fixtures 60–75 cm apart centre-to-centre.
- For wide rooms (e.g. 12×8 ft / 360×240 cm), use a 2×2 grid with lights 120–150 cm apart.
- Hanging height: 45–60 cm for vegetative growth; 25–40 cm for flowering.
- Airflow rule: pair every 600–800 W of LED power with appropriately sized extraction (6″ for ≤600 W, 8″ for 600–1200 W, 10″+ for higher loads).
Example multi-light setups:
- 240×120 cm (8×4 ft): two 300–400 W bar LEDs spaced ~65 cm apart.
- 300×150 cm (10×5 ft): three lights — a central unit with two flanking fixtures ~1 m apart.
- 360×240 cm (12×8 ft): four lights in a 2×2 grid, spaced around 130 cm.
- 300×300 cm (10×10 ft): six fixtures in a 2×3 grid for dense, high-demand canopies.
Pro tip:
Use a PAR meter or app to check uniformity — PPFD readings within ±15% across the canopy are ideal. For hanging height adjustments by fixture type, see our Grow Light Distance Chart
Conclusion
Whether you’re lighting a compact 2×2 tent or a full 10×10 grow space, matching your LED’s wattage, PPFD and coverage to the size of your tent is the key to getting healthy, productive indoor growth. By choosing efficient fixtures, monitoring canopy intensity and spacing lights correctly, you’ll achieve stronger, more even results year-round.
For more help building or refining your setup, explore our dedicated guides in the Grow Lights UK and Grow Tents UK hubs — both packed with practical advice, comparisons and setup tips for home growers.
Your plants grow better when your lighting plan does. 🌱
For broader comparisons across all budgets and grow styles, you can also explore our Top 10 LED Grow Lights UK guide.
📎 Related Articles
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• Top 10 LED Grow Lights UK
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• Best Indoor Grow Lights UK for Beginners
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• Top Grow Light Stand Systems
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• Grow Light Distance Chart UK
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• How to Set Up Grow Lights
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❓ Frequently Asked Questions (Grow Lights & Tent Sizes)
What are the best grow lights for different tent sizes?
The best grow lights for your tent size depend on matching real LED wattage and PPFD to your floor area. Small tents like 2×2 ft work well with 100–150 W LEDs (e.g., Spider Farmer SF1000), medium tents such as 3×3 or 4×4 ft perform best with 200–600 W bar-style LEDs, and larger tents 5×5 ft and above require high-output or multi-light bar systems for even canopy coverage. Your tent’s footprint is the biggest factor that decides which grow light is most effective
How many watts do I need for a 4×4 grow tent?
Most 4×4 tents perform best with 450–600 W of actual LED draw, which typically produces 900–1,000 µmol/m²/s across the canopy. A high-quality bar-style light such as the Mars Hydro FC-E4800 is ideal for full-cycle growing in this size.
How many lights should I use in a large grow tent?
Tents larger than 1.5 m (5 ft) in either direction usually need multiple LEDs for even coverage. Examples include:
8×4 ft: two lights spaced 60–75 cm apart
10×5 ft: three evenly spaced fixtures
12×8 ft: four lights in a 2×2 grid
Multi-light setups prevent edge dimming and allow better PPFD balance.
How high should LED grow lights be above plants?
Most LEDs perform best at 25–45 cm above the canopy, depending on dimming level and growth stage. Hang lower during flowering for higher PPFD, and higher during early veg to avoid stress. For exact model-by-model recommendations, see our Grow Light Distance Chart.
How do I calculate the right amount of light for my tent?
Multiply your tent’s floor area by 30–40 watts per sq ft, or use 320–430 W per m² for metric calculations. For example, a 4×4 ft tent (16 sq ft) requires around 560 W of total LED draw. Our coverage chart lists the ideal wattage and PPFD levels for every tent size.
Are LED grow lights energy efficient for indoor tents?
Yes. Modern LEDs from brands like Spider Farmer, Mars Hydro and AC Infinity offer 2.5–3.0 µmol/J efficiency, providing high PPFD with far less heat and electricity use than older HID systems. This makes them ideal for both small and large UK grow tents.
Do I need ventilation fans with LED grow lights?
Yes. LEDs still produce heat, especially in enclosed tents. Pair every 600–800 W of lighting with:
at least one oscillating fan, and
an extractor fan sized 6″ for ≤600 W, 8″ for 600–1200 W, or 10″+ for higher loads.
Good airflow prevents heat pockets and keeps PPFD levels stable.
Does tent size change which grow light is best?
Absolutely. Larger tents require stronger lights with better spread and higher PPFD output. Small tents can use compact 100–200 W LEDs, while 4×4, 5×5 and commercial-sized tents benefit from bar-style fixtures or multi-light grids for even canopy coverage.