Free light tools
Four interactive calculators to plan battery life, LED strip power, color moods and patio string-light layouts. No sign-up, no downloads.
How long will battery fairy lights last?
Pick your battery, LED count, mode and timer. The estimate updates as you go. Twinkle and fade modes use less power than steady-on, and rechargeable NiMH cells hold slightly less charge than alkaline but save money over a season. Related: battery-operated fairy lights and fairy light battery guide.
Fairy light battery life calculator
Estimate how long a battery-operated string will glow. Move the sliders and watch the lights.
Estimate based on about 0.75 mA per micro LED at full brightness and 85% usable capacity. Cold weather and cheap cells shorten runtime.
How big a power supply does my LED strip need?
Enter the length and the watts per meter printed on the reel. We add 20% headroom (power supplies run cooler and last longer that way), round up to a common size and flag runs long enough to need power injection. Related: smart LED strip lights and how to cut and connect strips.
LED strip length and power supply calculator
Size the power supply, find the cut interval and see whether a long run needs power injection.
Each block in the preview is one powered section. Always check the watts-per-meter on your strip's label; it varies by brand.
Which light color fits the mood?
Color temperature is measured in kelvin: lower numbers are warm and candle-like, higher numbers are cool and daylight-like. Slide through the range or tap a mood to see how a room changes. Related: smart LED light bulbs and LED colors and moods.
Color temperature and mood picker
Slide through warm to cool white, or pick a mood, and preview how the room will feel.
How many string lights do I need for my patio?
Set the size of your patio or deck and choose a pattern. The planner adds drape and the run to your outlet, then counts strands, bulbs and the hooks or posts you'll need. Related: waterproof string lights and how to hang outdoor string lights.
Patio string light planner
Enter your space, choose a hanging pattern and get the strand count, bulbs and anchor points, with a plan drawing.
Includes about 10% for a gentle drape and 6 ft to reach the outlet. Check the maximum number of strands your lights can link end to end.