LED vs Fluorescent Running Cost
Fluorescent tubes grew a generation of seedlings and still do. What has changed is the wattage needed to do it.
By Scooter M. — An enthusiast who's genuinely into this. I read the manuals, compile the published specs, and do the math. No lab coat.
Published · How we pick
Photographs on this site are licensed stock and are illustrative of the fixture type. We do not own the units we write about.
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We have not tested these units. Everything below comes from the manufacturer’s own published specifications, or from arithmetic we have shown our working for. Where a figure is not published, we say so instead of estimating one. Read the method.
Quick picks
Efficacy is photons out per joule in. Where a manufacturer publishes it we quote theirs; where they publish photon output and wattage but not efficacy, we divide and label it as ours; where they publish neither, the cell says so rather than guessing. Tap a row for the full write-up.
| # | Product | Best for | Efficacy | Price |
|---|---|---|---|---|
| 1 |  Barrina T5 4ft Grow Light Strips The default seed-starting bar for good reasons — 4 ft long, linkable in series, cheap per foot — and the reason we built a coverage calculator, because Barrina publishes no photon data whatsoever. | LED in the T5 form factor | Not published | |
| 2 |  AC Infinity IONBOARD S22 The highest published efficacy of any fixture here at 2.7 umol/J, on Samsung LM301H diodes, with dimming in real 20% steps rather than a vague knob. | Best efficacy overall | 2.7 umol/J | |
| 3 |  Spider Farmer SF1000 Publishes PPF to two decimal places and an efficacy figure that actually divides out of it. That internal consistency is rarer in this category than it should be. | Panel replacement | 2.5 umol/J |
The reasoning
Before we compare anything, a naming problem has to be cleared up, because it causes more confusion in this category than any other single thing.
“T5” now means two different products
T5 originally described a fluorescent tube: T for tubular, 5 for five-eighths of an inch in diameter. A T5 HO (high output) fluorescent tube of 4 ft length typically draws around 54 W.
Today most products sold as “T5 grow lights” are LED strips in the same physical form factor. Barrina’s 4 ft T5 strips draw 20 W each. Same shape, same mounting, same name, roughly a third of the power.
So “is T5 or LED better” is often a question about two products that are both LEDs. Check the wattage: a 4 ft tube around 54 W is fluorescent, one around 20 W is LED.
Barrina publishes 20 W per 4 ft LED strip. A T5 HO fluorescent tube of the same length is typically around 54 W. Same fixture shape, very different meter reading.
The running cost difference
T5 HO fluorescent: 4 × 54 W = 216 W. 216 × 16 ÷ 1000 = 3.46 kWh a day. Over 70 days = 242 kWh = $44.38.
LED strips: 4 × 20 W = 80 W. 80 × 16 ÷ 1000 = 1.28 kWh a day. Over 70 days = 89.6 kWh = $16.43.
A difference of about $28 for one seed-starting season, on four tubes. On a bigger rack it scales linearly.
The honest caveat, and it is a real one: this compares power draw, not delivered light. Neither Barrina nor the fluorescent tube publishes a photon output figure we can use, so we cannot tell you the two setups deliver equivalent light. What we can say is that LED replacements in this form factor are marketed as equivalents and draw about a third of the power.
Beyond the meter
| Factor | T5 fluorescent | LED strip |
|---|---|---|
| Power for a 4 ft tube | About 54 W | About 20 W |
| Output over time | Declines through tube life; replacement is periodic | Long rated life; Spider Farmer publishes 55,000 hours for its panel |
| Consumables | Tubes are replaced; ballasts eventually fail | None in normal use |
| Heat | Warm; ballast adds more | Cooler at the same output |
| Distance to plants | Can sit close, which is why it suited seedlings | Also sits close; this was never the fluorescent advantage people think |
| Disposal | Contains mercury; requires proper disposal | Ordinary electronics disposal |
Should you replace working fluorescent tubes?
On the numbers above, a four-tube seed rack saves about $28 a season. If replacement strips cost more than that, the payback is longer than one season — which is fine, but it should be a deliberate calculation rather than an assumption that newer is automatically cheaper.
Our view: do not throw out working tubes on efficiency grounds alone. Replace them with LED as they fail, which converts a sunk cost into a decision you were going to make anyway. If you are buying new from scratch, buy LED — there is no argument for starting with fluorescent today.
The seed-starting version of this comparison, including the light-quality question rather than just the cost, is in T5 versus LED for seed starting.
Every pick in full
Barrina T5 4ft Grow Light Strips
LED barLED in the T5 form factor
The default seed-starting bar for good reasons — 4 ft long, linkable in series, cheap per foot — and the reason we built a coverage calculator, because Barrina publishes no photon data whatsoever.
What Barrina publishes
- Power draw
- 20 W per fixture; an 8-pack draws 160 W (source)
- Spectrum
- 5000 K (source)
- Dimming
- No; on/off switch per fixture, linkable up to 8 in series (source)
- Dimensions
- 4 ft strip, 120-degree beam angle, 120 V AC (source)
What Barrina does not publish
- PPF in umol/s — for any strip in the range
- PPFD at any stated distance
- Photon efficacy in umol/J
- LED count per strip, and rated lifespan
Who should skip it
Skip it if you need to know what you are getting before it arrives. There is no published PPF, no PPFD and no efficacy figure, so nothing about its output can be verified in advance.
AC Infinity IONBOARD S22
LED panelBest efficacy overall
The highest published efficacy of any fixture here at 2.7 umol/J, on Samsung LM301H diodes, with dimming in real 20% steps rather than a vague knob.
What AC Infinity publishes
- Power draw
- 115 W (source)
- Efficacy
- 2.7 umol/J (source)
- PPFD
- 1098 PPFD (no measurement distance published) (source)
- Stated coverage
- 2 x 2 ft (source)
- Spectrum
- Samsung LM301H, plus 660 nm, 730 nm, 3000 K, 6500 K (source)
- Diodes
- 272 diodes (source)
- Dimming
- Yes, 0-100% in 20% increments (source)
- Dimensions
- 30.0 x 30.0 cm board, 1.1 cm thick (source)
- Rated life
- 50,000 hours (source)
Our arithmetic
- Photon output implied by the published wattage and efficacy: about 311 umol/s
115 W x 2.7 umol/J = 310.5 umol/s. AC Infinity does not print PPF directly, so this is our arithmetic from two figures it does print.
What AC Infinity does not publish
- PPF in umol/s — only efficacy is given, so photon output has to be derived
- The measurement distance for the 1098 PPFD figure, without which the number cannot be compared to anything
Who should skip it
Skip it if you want to place it by the numbers. AC Infinity prints 1098 PPFD with no measurement distance attached, which makes that figure impossible to use or compare.
Spider Farmer SF1000
LED panelPanel replacement
Publishes PPF to two decimal places and an efficacy figure that actually divides out of it. That internal consistency is rarer in this category than it should be.
What Spider Farmer publishes
- Power draw
- 100 W +/-5% at 100-277 V AC (source)
- PPF (photon output)
- 249.21 umol/s (source)
- Efficacy
- 2.5 umol/J (source)
- Stated coverage
- 2 x 2 ft core, 3 x 3 ft maximum (source)
- Spectrum
- 650-665 nm, 730-740 nm, 2800-3000 K, 4800-5000 K (source)
- Diodes
- Bridgelux (source)
- Dimming
- Yes, dimming knob (source)
- Dimensions
- 32.5 x 29.0 x 5.9 cm (source)
- Rated life
- 55,000 hours (source)
Our arithmetic
- Does the published efficacy check out against the published PPF?: Yes — 2.49 umol/J computed against 2.5 umol/J published
249.21 umol/s / 100 W = 2.4921 umol/J. The published 2.5 umol/J is that number rounded. Not every brand's two figures agree like this, which is exactly why we divide them. - Average PPFD across its 2 x 2 ft core footprint: about 536 umol/m2/s
2 ft x 2 ft = 4 sq ft = 0.372 m2. 249.21 / 0.372 = 670 umol/m2/s at perfect uniformity; at a 0.8 uniformity factor, about 536 umol/m2/s.
Who should skip it
Skip it if raw output is what you are buying — the TS 1000 delivers 38% more photons per second, at the cost of 50 W more draw.
Questions people actually ask
+Do LED grow lights use less electricity than fluorescent?
+Is a T5 light fluorescent or LED?
+Should I replace my fluorescent grow lights with LED?
+Do fluorescent tubes get dimmer over time?
Sources
- Barrina — T5 ML20 4ft 20W product page — consulted September 2, 2026
- Spider Farmer — SF1000 published specification table — consulted September 2, 2026
- US Energy Information Administration — Electric Power Monthly, Table 5.3 (US residential average, June 2026) — consulted September 2, 2026
- University of Minnesota Extension — Lighting for indoor plants and starting seeds — consulted September 2, 2026
Read next
Seed Starting
T5 Fluorescent vs LED for Seed Starting
LED wins on hours, cost and lifespan. The one remaining case for fluorescent, stated honestly.
Running Cost
The Most Efficient Grow Lights by µmol/J
Every fixture we cover ranked on published photon efficacy, with derivations shown.
Running Cost
LED vs HPS Running Cost
What an LED panel actually saves against the HPS lamp it claims to replace.
Running Cost
How Much Electricity Do Grow Lights Use?
Monthly kWh and cost per fixture, and how that compares with household appliances.
Where this sits
This page belongs to Running Cost and Efficiency. Every figure on it is either quoted from a named published source or derived in view — the full method is on our methodology page, and how the site is funded is on the affiliate disclosure.