SettingsSettings for this calculationUS
The sum of the wattage of every fixture on this run.
Add up the wattage printed on each landscape light fixture connected to this wire run.
The distance from the transformer to the fixture (or the farthest fixture on the run).
Measure the actual cable path, not a straight-line distance, if the wire is routed around obstacles.
Tools needed: Tape measure
Lower AWG numbers mean thicker wire with less resistance.
Thicker wire (lower AWG number) supports longer runs and more total wattage before voltage drop becomes a problem.
Voltage drop
0.794 V drop
Voltage drop is moderate — acceptable for most installs, but a thicker wire would improve brightness consistency.
- Current draw
- 5 A
- Voltage drop
- 6.62 %
- Voltage at fixture
- 11.21 V
They open the calculator with your figures already in it
Landscape Lighting Wire Calculator: 0.7938 V drop — 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)
- Voltage drop (round trip) = 2 x current (A) x resistance per foot x length (ft), using standard uncoated-copper DC resistance at 25 C: 1.02, 1.62, 2.58 and 4.09 ohms per 1000 ft for 10, 12, 14 and 16 AWG
- For 12V landscape lighting, keeping voltage drop under about 10% (1.2V) is a common guideline to avoid dim or flickering fixtures
Inputs used
- Total Fixture Wattage
- 60
- One-Way Run Length
- 49 ft
- Wire Gauge (AWG)
- 12 AWG (common)
Intermediate steps
- Current draw
- 5 A
- Voltage drop
- 6.62 %
- Voltage at fixture
- 11.21 V
Confidence note: Voltage drop is moderate — acceptable for most installs, but a thicker wire would improve brightness consistency.
What this calculation does not cover
- This is a voltage-drop check, not an ampacity check. It never asks whether the gauge you picked can carry the current without overheating - 300 W, the maximum this page accepts, is 25 A at 12 V, and on a short run it will report a small drop on 16 AWG and say nothing about the wire. Size the cable against its own current rating and the transformer's per-terminal fuse separately.
- It puts the entire fixture wattage at the single distance you enter. Fixtures spread along a daisy-chained run see less drop than this shows, and hub, tee and loop layouts split the current between legs. Treat the answer as a worst case for one leg, not as a layout tool.
- The supply is fixed at 12.0 V. Multi-tap transformers deliver 13, 14 and 15 V taps, transformer output sags under load, and the LED drivers in modern fixtures behave as constant-power loads that pull more current as voltage falls. The linear model here follows none of that, and it stops meaning anything once the computed drop approaches the supply voltage.
- Resistance comes from a DC table for uncoated copper at 25 C. Warm soil, sun-heated cable above ground and tinned conductors all raise it, and the calculation carries nothing for connectors, splices or terminal blocks - a corroded waterproof joint can add more drop than the cable it joins.
- Nothing here covers cable selection or installation: direct-burial rating, burial depth, physical protection, or what your local rules require for exterior low-voltage wiring.
Add the equipment this sizes
This result is a specification — 0.794 V drop — 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 citations2
- Voltage drop (round trip) = 2 x current (A) x resistance per foot x length (ft), using standard uncoated-copper DC resistance at 25 C: 1.02, 1.62, 2.58 and 4.09 ohms per 1000 ft for 10, 12, 14 and 16 AWG
- For 12V landscape lighting, keeping voltage drop under about 10% (1.2V) is a common guideline to avoid dim or flickering fixtures
Cite this page
Your workspace
Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.
Protection this work requires
- Stop and check first. Textured ceiling coatings, board behind panels, floor tiles and bitumen adhesive in older buildings — built before asbestos was banned or phased out where you are — can contain asbestos, and drilling or sanding them releases fibres. Do not disturb it — have it sampled first. This is not a job for better PPE.
Tools and safety for this job
To first-fix electrical. Generic types, no brands, no prices.
- Assume every cable is live until proved dead at the point you will touch, with a two-pole tester you have just proved on a known source.
First-fix electrical: This site does not publish a tool list for electrical installation work. In every market it serves, fixed wiring is either reserved to a registered electrician or notifiable to a building authority, and the failure mode is a fire or an electrocution months later rather than a visibly bad job on the day. The calculator gives you the quantities to discuss and to buy against. The installation is a job for a qualified electrician, and the certificate they issue is the point of them.