8 of the 13 features in our table differ between the SCD40 and the SCD30.
CO₂ · temperature · humidity · I²C · 2.4 to 5.5 V
Sensirion’s small photoacoustic CO₂ sensor: ±(50 ppm + 5 %) from 400 to 2,000 ppm, 2.4 to 5.5 V, I²C.
Watch out: Specified only up to 2,000 ppm: for greenhouses or higher levels, choose the SCD41.
CO₂ · temperature · humidity · I²C/UART · 3.3 to 5.5 V
Sensirion’s NDIR module: ±(30 ppm + 3 %) up to 10,000 ppm, plus temperature and humidity.
Watch out: Bigger and hungrier than the SCD4x (19 mA on average). Its own warmth affects the temperature reading: set the offset.
| Feature | SCD40 | SCD30 |
|---|---|---|
| Technology | Photoacoustic NDIR | NDIR (infrared) |
| CO₂ range | 400 to 2,000 ppm | 400 to 10,000 ppm |
| CO₂ accuracy | ±(50 ppm + 5 %) | ±(30 ppm + 3 %) |
| Interface | I²C | I²C, UART |
| I²C address | 0x62 | 0x61 |
| Supply | 2.4 to 5.5 V | 3.3 to 5.5 V |
| Lowest average current | 3.2 mA | 19 mA |
| ESPHome | scd4x | scd30 |
Same on both: measures · status.
Open the sensor comparison →Tick what your project needs and see which sensor fits best.
SCD40: I²C address, wiring and pull-ups →
SCD30: I²C address, wiring and pull-ups →
The SCD40 offers a lower average current. The SCD30 offers better CO₂ accuracy and a wider CO₂ range.
Both measure real CO₂: ±(50 ppm + 5 %) for the SCD40 (400 to 2,000 ppm), ±(30 ppm + 3 %) for the SCD30 (400 to 10,000 ppm).
Often yes: both use I²C. Change the driver or, in ESPHome, the component (scd4x → scd30). The I²C address changes too (0x62 → 0x61).
SCD40 vs MH-Z19C SCD40 vs SCD41
Figures from the makers’ datasheets and product pages and the ESPHome documentation, checked in November 2026.