# Extech RH25 Heat Index Psychrometer

# Extech RH25 Heat Index Psychrometer

## Key Features At A Glance

-   Pocket-sized pen-style design (5.5 x 1.4 x 0.7 inches, 1.8 oz) for portable monitoring of heat stress conditions
-   Built-in multiparameter sensor measures Heat Index, WBGT, Relative Humidity, Ambient Temperature, Dew Point, and Wet Bulb
-   Heat Index combines humidity with temperature, air movement, and radiant heat to indicate how hot conditions actually feel
-   Wet Bulb Globe Temperature (WBGT) accounts for temperature, humidity, and direct or radiant sunlight effects
-   User-programmable Heat Index and WBGT alarm thresholds for proactive heat stress alerts
-   Min/Max/Average recording with Data Hold function
-   Auto power off with disable option; powered by included CR2032 battery

The Extech RH25 is a pocket-sized Heat Index Psychrometer Pen designed to monitor heat stress conditions during hot, humid days. Its pen-style form factor and 1.8 oz weight allow it to fit easily into a pocket, making it convenient to carry for spot measurements wherever needed.

Per the datasheet, the RH25 is intended to help prevent heat stroke during outdoor activities, sporting events, and indoor workplace environments. The instrument supports six measurement and calculation modes — Relative Humidity, Heat Index, Temperature, Dew Point, Wet Bulb, and Wet Bulb Globe Temperature (WBGT) — covering the parameters most relevant to assessing heat-related risk.

ValueTronics stocks, inspects, and ships test and measurement instruments from a 20,000 sq ft secure warehouse at 1675 Cambridge Drive in Elgin, Illinois. Equipment is verified by our in-house technicians before shipment — not drop-shipped from a third party — which lets us stand behind every unit we sell and respond directly when questions arise.

## Accessories Supplied

-   CR2032 battery

## Product Core & Specifications

Specifications

Range

Resolution

Basic Accuracy

Temperature

\-4 to 122°F (-20 to 50°C)

0.1°F/C

±1°F/0.6°C

Relative Humidity

0 to 99.9%RH

0.1%RH

±3%RH

Wet Bulb

\-4 to 122°F (-20 to 50°C)

0.1°F/°C

Dew Point

\-108.4 to 122°F (-78 to 50°C)

0.1°F/°C

Heat Index

\-50.8 to 401°F (-46 to 205°C)

0.1°F/°C

WBGT

\-13 to 130°F (-25 to 54.5°C)

0.1°F/°C

Dimensions

5.5x1.4x0.7" (140x35x18mm)

Weight

1.8oz (50g)

**Important:** Heat Index measures how hot it feels when humidity is combined with temperature, air movement, and radiant heat. Wet Bulb Globe Temperature (WBGT) considers the effects of temperature, humidity, and direct or radiant sunlight.

**Please review the Manufacturer's Data Sheet to verify published specifications. Feedback on this webpage is always welcome — please reach out to your Test Architect at any time for questions or concerns. Thank you, we truly appreciate you being our customer.**

## Details

- **Price:** 119.0 USD
- **Vendor:** Extech
- **Type:** Data Log
- **Tags:** Extech, Manufacturers, Meters & DAQ, Other, product_manual_group_2, Product_new

## Variants

| Variant | Price | Available |
|---------|-------|-----------|
| Default Title | 119.00 USD | In stock |

## Images

- RH25 Extech Meter

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> Source: [ValueTronics](https://valuetronics.com/products/rh25-extech-meter-new)
> Updated: 2026-05-30