LED Tube Sizes Explained: 2ft, 3ft, 4ft & 8ft T8 — How to Choose

Replacing fluorescent tubes with LED is one of the best returns in lighting — but first you need the right size. LED tubes come in several standard lengths, and matching yours is the key to a clean swap. Here's the full rundown.

Match the Length to Your Fixture

LED tubes are sold by nominal length, which corresponds to the fluorescent tube they replace:

• 2 ft — typically 10W LED, ~1,200 lumens. Replaces 2-foot F17T8 tubes in small fixtures, under-cabinet, and cove lighting.
• 3 ft — typically 12W LED, ~1,600 lumens. Replaces 3-foot F25T8 tubes.
• 4 ft — the most common, usually 15W–18W LED, ~1,800–2,250 lumens. Replaces the ubiquitous 4-foot F32T8 tube in shop lights, troffers, and kitchens.
• 8 ft — typically 40W LED, ~4,400+ lumens. Replaces 8-foot fluorescent tubes in warehouses, garages, and industrial fixtures (often single-pin FA8 base).

Measure your existing tube end-to-end if you're unsure. Browse all sizes in our LED Tubes collection.

Shop by Lumens, Not Watts

An LED tube uses far less power than the fluorescent it replaces, so don't match wattage — match lumens. A 15W–18W LED easily replaces a 32W fluorescent 4-footer because it produces the same 1,800–2,250 lumens for roughly half the energy. Many 4-ft LED tubes are also multi-wattage (selectable 12/15/18W), letting you dial in brightness per fixture.

Choose a Color Temperature

Tubes set the tone of work and retail spaces:

• 3000K–3500K — warmer, for retail and display areas.
• 4000K — neutral, a versatile all-purpose white.
• 5000K — crisp daylight, ideal for garages, warehouses, and workshops where detail matters.

Clear vs. Frosted Lens

Clear lenses give maximum brightness and a slightly crisper beam (good for high ceilings and shop lighting). Frosted lenses diffuse the light for less glare and a smoother look (better for occupied rooms and lower mounting). Output is similar; it's mostly about glare control.

Don't Forget the Tube Type

Length and brightness aside, you'll choose how the tube handles the ballast — Type A (plug-and-play), Type B (ballast-bypass), or Type A+B (universal). Our Type A/B/C guide explains which to pick. Also confirm the base — most T8 tubes use a G13 bi-pin; many 8-ft tubes use a single-pin FA8.

Buy in Bulk and Save

Tubes are usually replaced a whole fixture — or a whole room — at a time, so they're a natural for multipacks. Our LED tubes come in singles plus 6-packs and 12-packs at a discount, and our quantity pricing stacks on top for larger jobs. Browse the LED Tubes collection to find your size, or check the glossary for any term that's new.