Find the Right Light for Your Houseplants

Estimate lux levels, window orientation light hours, and matched plants — all from your browser. Uses your phone's ambient light sensor when available, with fallback for unsupported devices.

Start Estimating

How It Works

Four steps to plant-perfect light estimation, no app required.

1

Grant Permission

The browser asks to read your device's ambient light sensor. Tap Allow. This is the same sensor that auto-brightens your phone screen.

2

Take a Reading

Hold your phone where the plant sits, pointing at the light source. A live lux reading appears instantly.

3

Select Orientation

Pick your window's cardinal direction: North, South, East, or West. We combine this with your sensor reading.

4

Get Matches

We estimate light intensity, direct vs indirect hours, and show matched houseplants for your exact spot.

The Calculator

Combine your live reading with window orientation for plant-perfect guidance.

Live Light Reading

Hold your phone where the plant sits, pointing at the window.

— lux

Your Estimate

Estimated light level: Medium

Approximate lux range: ~1,080–5,400

Light Hours Estimate

Direct Sun 4–6+ hours hours
Indirect Light Most of the day hours

Plants That Match This Light

African violet

Light needs: 200–400 fc indirect

Notes: Tolerates ~2–3 hr direct sun

Alocasia

Light needs: 200–400 fc indirect

Notes: Leaves may drop in low light

Areca palm

Light needs: 200–400 fc indirect

Notes: Needs more as it grows

Begonia (several species)

Light needs: 200–400 fc indirect

Notes: Keep soil evenly moist

Calathea (prayer plant)

Light needs: 200–400 fc indirect

Notes: Bright but indirect

Ceropegia (string of hearts)

Light needs: 200–400 fc indirect

Notes: Variegation improves with more light

Phalaenopsis (moth orchid)

Light needs: 200–400 fc indirect

Notes: Tolerates ~2–3 hr direct sun

For best results, take readings at different times (morning, midday, late afternoon). Glass clean-up adds up to 50% more light!

Light-Level Reference

Typical Light Levels by Band

Midday readings from University of Florida IFAS, with approximate lux conversions.

Light Level Foot-candles [UF/IFAS] Approx Lux [derived] What it means
Low 25–100 ~270–1,080 Little natural light; far from windows
Medium 100–500 ~1,080–5,400 Near a window, no direct sun
Bright 500–1,000 ~5,400–10,800 Unshaded east/west or shaded south window
Very bright / direct sun Over 1,000 Over ~10,800 Directly in front of unshaded window

Window Orientation Light Behavior

Guidance from university extension services.

Window Typical Intensity Direct Sun Indirect Light Best Uses
South Highest (100% of south) Direct within 2–3 ft, all day Bright indirect up to 5 ft Bright/direct-sun lovers
East ~60% of south Morning only (~2–4 hrs) Indirect up to 5 ft Morning sun lovers
West ~60% of south Afternoon/evening (~2–4 hrs) Indirect up to 5 ft Afternoon sun lovers
North ~20% of south Generally none Low, even direct at sill Low-light lovers

Frequently Asked Questions

Why does the browser ask for permission?
The Ambient Light Sensor API is gated behind the Permissions API for privacy — the browser won't hand a website your device's ambient light readings without you explicitly allowing it. Granting permission only lets this page read a brightness number in lux; no data leaves your device.
Does it work on desktop?
Sometimes. The modern Ambient Light Sensor API is supported in Chromium-based desktop browsers, but only on devices that actually have an ambient light sensor — which means mainly laptops with light sensors, not most desktop towers. On a device without a sensor (or a browser without support), the tool clearly says the sensor isn't available and falls back to orientation-only guidance plus a manual lux estimate. The legacy devicelight event that once filled this role is obsolete, so don't count on it.
How accurate is a phone light sensor?
Good enough to separate low, medium, bright, and direct-sun spots — the level of answer most houseplants need — but not a substitute for a professional light meter. Phone-app and sensor-based readings vary by device and calibration, and are best treated as approximations for telling relative brightness, not absolute horticultural precision. Take readings at a few times of day for the honest picture.
Is it a substitute for a professional light meter?
No. This is a general-guidance tool for helping you choose a spot and a plant. If you're growing light-critical or collection-grade plants and need precise, consistent numbers, use a proper digital light meter that reads in foot-candles or lux. Use this tool to get close and right, and treat the sensor figure as guidance, not certification.

Important Disclaimer

Disclaimer: Window Light Finder provides light-level guidance for home use only, for general informational purposes. All sensor readings and solar estimates are approximations based on your browser and device hardware capabilities, and actual light intensity and hours vary with the season, time of day, window shading, curtain/foliage, and the cleanliness of the glass. Results are general guidance, not professional horticultural measurement, and should not be relied on as a substitute for a calibrated light meter or professional growing advice. Light needs vary by individual plant, cultivar, and situation. Hekatix is not liable for plant health, leaf burn, growth, or any other outcome for your plants, nor for errors or omissions in these estimates.