SettingsSettings for this calculationUS
The total length of LED strip in the run, including any joined reels.
Add up all connected strip segments powered from this one supply.
Check your specific strip's spec sheet — this varies by LED density and brightness.
Standard-density 12V 5050 strips draw roughly 2-2.4 W/ft; high-density or COB strips can draw 4-6+ W/ft.
Extra headroom so the supply isn't run at its rated maximum continuously.
20% is a common recommendation for LED driver longevity and to allow for future strip additions.
Recommended power supply size
47.5 W (recommended supply rating)
Always confirm against your specific strip's datasheet watts/ft rating — this varies significantly between products.
- Raw strip load
- 39.6 W
They open the calculator with your figures already in it
LED Strip Power Supply Calculator: 47.52 W (recommended supply rating) — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
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How this was calculated
Formula source(s)
- Total load = strip length x watts per foot (from the strip's spec sheet); a safety margin keeps the power supply from running at its rated maximum continuously
Inputs used
- Total Strip Length
- 16.5 ft
- Strip Draw (Watts per Foot)
- 2.4
- Safety Margin (%)
- 20
Intermediate steps
- Raw strip load
- 39.6 W
Confidence note: Always confirm against your specific strip's datasheet watts/ft rating — this varies significantly between products.
What this calculation does not cover
- The result is DC output watts only. It does not check voltage drop, set feed points, or size the low-voltage wiring — a long 12 V run can dim visibly at the far end even with a correctly rated supply, and the cable and connectors have to carry the current, not the watts.
- Watts per foot is treated as one flat figure for the whole run. Nothing accounts for an RGB or RGBW strip drawing more at full white than a single-channel rating suggests, for controllers, amplifiers or receivers powered from the same supply, or for the spread between a datasheet figure and the reel actually in hand.
- This is not a branch-circuit or load calculation. The figure is the driver's output rating: it says nothing about the AC circuit feeding it, the supply's own conversion losses, overcurrent protection, or whether the total exceeds what a Class 2 listed driver is allowed to deliver.
- The safety margin is flat headroom, not a manufacturer derating curve. A supply mounted in a hot, enclosed or unventilated space often has to be derated further than the percentage entered here, and nothing checks the driver's ambient or ingress rating against where it is going.
- Driver type and control method are outside the model. Constant-current strips, mains-dimmable drivers and PWM or 0-10 V dimming each carry their own minimum and maximum load requirements, so a supply sized purely on total watts can still sit below a dimmer's minimum load or be incompatible with it.
Add the equipment this sizes
This result is a specification — 47.5 W (recommended supply rating) — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.
Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.
Sources checked 2026-09-02 · in the site-wide review of 2026-09-06 · v1.0.1
Regulatory standards & verification citations1
- Total load = strip length x watts per foot (from the strip's spec sheet); a safety margin keeps the power supply from running at its rated maximum continuously
Cite this page
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