Indicative light meter
A rough estimate of light intensity (EV) and colour temperature (Kelvin) via your camera.
A light meter tells you how much light falls on your subject, so you can judge your exposure. This indicative meter gives you a quick ballpark reading on location. Useful as a starting point, not a replacement for a dedicated meter.
How does the measurement work?
Browsers don't expose sensor data. EV is derived from pixel brightness, Kelvin from the red/blue ratio. Both are indicative. The tool automatically locks white balance and exposure on start where the device supports it. If that fails, set your camera app's white balance to a fixed preset (e.g. Daylight) manually.
Colour temperature (Kelvin)
Kelvin (K) measures the colour temperature of light. Low = warm (yellow/orange); high = cool (blue). This is counterintuitive: a cosy "warm" lamp has a low Kelvin value.
- ~1800-2500K
- Candlelight, fireplace
- ~2700-3200K
- Incandescent bulb, warm-white LED
- ~3200-4000K
- Halogen lamp, photo studio (tungsten)
- ~4000-5000K
- Neutral white (fluorescent, office)
- ~5500-6500K
- Daylight, camera flash
- ~6500-7500K
- Overcast day
- ~7500K+
- Open shade, blue sky
EV reference
EV (Exposure Value) is a logarithmic measure of light quantity. Each step up doubles the light. EV 0 = near darkness; EV 15 = bright sunlight.
- ≤ 3
- Candlelight, dark room
- 4-6
- Dim lamp, sunset
- 7-9
- Overcast interior
- 10-12
- Bright room, overcast outside
- 13-15
- Overcast daylight, shade
- 16-17
- Full sun
- ≥ 18
- Extremely bright (snow, beach)
Point your camera at the light source or the lit subject. Calibrate with a hardware meter for accurate shots.
Indicative Light Meter: how it works
The indicative light meter estimates light intensity based on what your camera sees. It gives you a quick reference on location without needing separate gear. Use it to get your bearings, not as a substitute for a calibrated meter.
How the tool estimates light levels
The tool reads the brightness from your camera feed and translates it into an estimated exposure value (EV). That number tells you roughly how much light is available, similar to what your camera's built-in meter reports.
Accuracy depends on your device. Sensors in phones and laptops are not factory-calibrated for light measurement, so the result is an approximation. For anything that requires precision, like setting up studio strobes, use a dedicated flash meter.
Practical uses on location
When you arrive somewhere new, you often want to know fast whether there is enough light to shoot handheld or whether you need a tripod. This tool gives you a rough read in seconds, without guessing at settings.
Common scenarios: scouting an indoor venue before a portrait session, checking whether window light is strong enough for a product shot, or noticing that light conditions have shifted significantly between two setups.
Frequently asked questions
How accurate is an indicative light meter running on a phone camera?
Expect a margin of 1-2 EV depending on the device and lighting conditions. For a quick reference that is fine; for precise calculations you need a calibrated meter.
When does a phone-based light meter fall short compared to a dedicated meter?
It struggles in mixed lighting, very low light, and any situation where you need exact flash output. A dedicated meter measures incident light directly, which this tool cannot do.
Which EV values correspond to common shooting situations?
EV 10-12 is overcast daylight outdoors. EV 5-7 is a well-lit office interior. Below EV 3 you are in dim or near-dark conditions where high ISO or a longer shutter speed becomes unavoidable.