LDR Resistance * Ohms (Ω)

Reference Lux (at R_ref) * Lux (lx)

Reference Resistance (R_ref) * Ohms (Ω)

Gamma (γ) * Dimensionless

10kΩ @ 10 lux (typical) 5kΩ → ~25 lux 20kΩ → ~4 lux 100kΩ → ~1.4 lux

— lx

Illuminance

R → Lux

Resistance (Ω) Lux (lx)

Illuminance (Lux) * Lux (lx)

Reference Lux (at R_ref) * Lux (lx)

Reference Resistance (R_ref) * Ohms (Ω)

Gamma (γ) * Dimensionless

10 lux → 10kΩ 25 lux → ~5kΩ 5 lux → ~16kΩ

— Ω

LDR resistance

Lux → R

Supply Voltage (Vcc) * Volts (V)

Series Resistor (Rs) * Ohms (Ω)

LDR Resistance * Ohms (Ω)

ADC Resolution (bits) Bit depth

Reference Lux (for display) Lux (lx)

Reference Resistance Ohms (Ω)

Gamma (γ) Dimensionless

5V, 10k pull-up, 10k LDR 3.3V, 10k pull-up, 5k LDR

— V

ADC voltage and value

Divider

Vout = Vcc × (R_ldr / (Rs + R_ldr))
Lux = Lux_ref × (R_ref / R_ldr)^1/γ