How To Measure Humidity In House (Without Hygrometer)

If you’re looking for ways on how to measure humidity in house, then this guide is exactly what you need. An overabundance of moisture in a living space can trigger mold and mildew or lead to health conditions such as allergies or related respiratory distresses.

While a hygrometer is normally used to check moisture levels, you can use alternative methods as well. To ensure comfort, the humidity in your dwelling should register between 40% and 50%.

To learn how you can ensure this type of comfort, you need to learn more about humidity so you can accurately measure it. Definitively, humidity represents the moisture level in the air.

A hygrometer quickly reads the moisture by showing the percent of humidity in the environment. While this method is quick and effective, you may not have a hygrometer at the ready. Therefore, the following options can serve as substitutes.

How To Measure Humidity In House

Using Ice Cubes

To apply this method, take four ice cubes and a glass of water. This technique shows how dry and humid the air is in your home. Simply plunk the ice into the glass of water and set the glass in a room where you believe that the moisture level may be too low or too high.

Just do not place the glass in the bathroom or kitchen where the moisture levels are not the same from time to time. Place the ice cubes and water on a table in the room and quickly exit as too much movement can impact the outcome.

Leave the water and cubes in the room for about five minutes. Inspect the glass. If condensation has formed on the outside of the glass, the moisture level is high.

To absorb the excess, you may want to consider adding plants that readily absorb atmospheric moisture. If the glass shows no signs of condensation, you may want to add a humidifier. Dry air can lead to health concerns as well, such as skin conditions, eczema, or headache pain.

Perform the Wet and Dry Bulb Temperature Test

Another easy way to figure the humidity is to use two old-fashioned thermometers (the kind with mercury and glass tubing). Use one of the thermometers as a “wet bulb” thermometer and use the other thermometer as a “dry bulb” measure.

Before proceeding with the experiment, shake the mercury in each thermometer so it settles in the bulb of each device. Moisten the wet bulb thermometer with a dampened piece of cotton, affixing the cotton to the thermometer’s bulb.

Use room temperature water for the experiment. Next, place and duct tape the wet bulb thermometer and dry bulb thermometer on a piece of cardboard. The bulbs should project outwards.

Switch on a fan where you want to check the moisture level, pointing it toward the thermometers. Allow the fan to run for about five minutes. After this period, check the temperatures on each thermometer.

Subtract the temperature for the wet bulb thermometer from the temperature of the dry bulb thermometer. For example, on the Celsius scale, a difference of 10 degrees Celsius, also called the depression value, shows the percentage of humidity.

To arrive at this value and the percentage, refer to a table that lists the percents of relative humidity. Tables are featured online that show the relative humidity (RH) in percentages using the wet and dry bulb measure. Examples can be found, for instance, on the Engineering ToolBox site online.

Use Your Hair as a Hygrometer

The hair expands when it is exposed to excess moisture and contracts in dry climates. Based on this scientific fact, you can tell if the air is dry or moist by checking a strand’s length.

When the air dampens, hair increases in length; when the air lacks moisture, hair decreases in length. To check this out, you need to draw an arrow. Cut out the arrow and insert at the bottom.

The hole should be slightly larger than the needle of a pin. Pin the arrow on a piece of cardboard, making sure that it can easily spin. Wrap a strand of hair around the pin and pin it above the arrow on the cardboard.

Secure the other end of the strand around the arrow. Blow dry the strand first for about a minute. The hair will shrink, causing the arrow to move upwards. This represents a point for 0% moisture.

Next, spray water on the strand. Doing so will cause the arrow to move down, indicating 100% humidity. By referencing these points, you can determine the amount of humidity in the air.

By using the above methods, you will find out how humidity is important in terms of atmospheric comfort. Indeed, measuring the humidity level is relevant as this measurement is used in a large number of testing, storage, and manufacturing processes.

Humidity measurements are required in places where a need exists to reduce the level of condensation, prevent corrosion, or stop the formation of mold.

Excessive humidity can also lead to spoilage or the warping of materials. Therefore, this scientific measure plays a huge role in the manufacture and shipment of pharmaceuticals, fuels, chemicals, paper, and wood.

Air-conditioning systems frequently control humidity levels using a good deal of energy to remove the vapor in the air. Therefore, this measurement, when used to balance moisture levels, contributes to reducing energy costs and maintaining the proper environmental conditions.

The Pine Cone: Another Type of Hygrometer

One of the natural hygrometers in nature is the pine cone. The cone opens when the air is dry to release its spores. While you cannot test the humidity in a room with this natural hygrometer, the amount of moisture in the air can be shown to impact both indoor and outdoor activities and developments.

Some Basic Concepts

To understand the measurement of moisture, you also should consider some basic concepts. For example, water vapor reacts similarly to a gas and condenses to form either ice or water, depending on the temperature.

Even if it does not condense, water vapor can still penetrate materials or react to certain surfaces. The capacity of a space to hold moisture depends on the temperature. Higher temperatures hold more moisture than colder temperatures.

Relative Humidity

When measuring humidity, keep in mind that it can be expressed in one of varying ways. For example, the relative humidity is the most frequently used measurement.

Relative humidity is typically expressed in the form of a percentage with the following symbol – %rh. The interaction of a water vapor with certain materials forms the basis for relative humidity readings.

The Dew-Point Temperature

Dew point, or the dew-point temperature reading, is another way that humidity is read. The dew point represents the temperature at which dew occurs if a gas cools. Dew point measures provide the following information:

  • The reading shows what temperature to maintain a gas to avoid condensation.
  • This reading is a precise and overall measure of gas humidity, regardless of the temperature. Therefore, it directly relates to the amount of vapor present.
  • Dew point is always expressed in the form of a temperature reading. If the temperature goes below the freezing point, the term frost point applies.

Using a Ratio or Fraction as a Measurement

A ratio or fraction expresses the amount of water vapor within a gas. This measure may represent the volume of a substance or be registered in terms of mass.

Concentrations of Vapor

A concentration of water vapor shows the mass of vapor for each unit volume. For instance, the air in a space may contain about 10 grams of vapor for each cubic meter of space.

Other Points to Consider

You should also consider these other important concepts:


When a space or a gas holds the optimum water vapor at a certain temperature, it is classified as being saturated. If additional water is added to the saturated gas or if the temperature falls, the vapor condenses.

Partial Pressure

Partial pressure represents another measure of water vapor. For example, air, which is a gas mix, is made of pure gas elements such as nitrogen and oxygen.

The total sum of this type of gas is stated in terms of the total of the partial pressures. The air in a room may contain a partial pressure of water vapor that reads 1,000 pascals (Pa).

Super-Cooled Water

Water that is supercooled below the freezing point may develop dew, which appears in this form of water occasionally. The dew eventually freezes to ice.

Sensing the Humidity in the Air: Types of Measuring Devices

Now that you understand a little about water vapor concepts, you can see how hygrometer-type measurements are used to sense humidity.

For example, the aforementioned wet-and-dry bulb thermometer measurement senses the humidity by determining the evaporative cooling on a wet surface.

Color Changes

You can also determine moisture levels though changes in color. For example, inks or crystals that contain cobalt chloride or similar chemicals change their hue when excess moisture exists. You can also use a relative humidity sensor to find the relative humidity.

The device indicates an electrical change when water vapor is absorbed into a polymer type film. A dew-point probe also uses electrical change to measure the absorption of humidity into a porous metal oxide type of film.

Weighing Masses of Water

A gravimetric may be used, too, to weigh a mass of water, which increases and decreases based on a sample of humid air. Mechanical means such as the above-mentioned hair sample measure water by calculating the dimensional change in humidity-sensitive materials. Besides hair, polymers or paper can be used.

Light Can Be Used to Sense Humidity Too

An optical fiber can also support changes in humidity with the transmission or reflection of light. This is done by experimenting with an optical grating or hygroscopic coating.

Some scientists use a quartz crystal resonator to learn more about changes in resonant frequency produced by a mass of surface-absorbed water. Zirconia can also be used as a measurement. The amount of humidity is derived from the amount of oxygen in a gas.

Questions to Ask

When measuring humidity, you need to consider the following:

  • Do you want to measure the dew point or relative humidity?
  • What do you want to use for a humidity range and temperature range? Certain products will not survive extreme conditions such as hot or wet climates or very dry environments.
  • Does contamination exist? Dust or chemicals can prove to be hazardous to the health, depending on the humidity level.

Points to Keep in Mind

When making any type of humidity measurement or determining the moisture level in a room, you need to keep the following in mind:

  • The appearance of water droplet or any type of stray water may give you the wrong humidity results.
  • Always watch out for dust as it can lead to the wrong reading or calculation.
  • Check pressure differences with respect to the dew point or temperature variations with respect to the relative humidity.

When Hygrometers Do Not Work

You may want to use the makeshift tools described above instead of a hygrometer as hygrometers are not fail-proof. Sometimes the readings are not correct. If you suspect problems along these lines, you need to do the following:

  • Make sure that the equipment is switched on properly and everything is connected.
  • Find out if the instrument and the conditions are stabilized.
  • Check the temperature if you are recording the relative humidity.
  • Check the calibration.
  • Compare the reading of the gauge with another hygrometer.
  • Review any human mistakes such as recording errors or numbering mistakes.

Making Calculations

It helps to bone up on math as well when you are figuring humidity readings. Different methods are used to determine the moisture level in terms of dew point, vapor pressure, or relative humidity.

If you do have access to a hygrometer, the instrument usually comes with a software to make moisture conversions. Whether you use the software or not, you should have a basic understanding of how this type of measure is figured.

For instance, when relative humidity is expressed in a percentage, it takes the actual vapor pressure and divides it by saturation vapor pressure at the actual temperature and pressure.

This amount is multiplied by 100. This equation shows that the relative humidity represents a fraction of the water saturation at a certain temperature.

Once you find out more about the concepts of humidity and the various ways that it can be calculated, you will find that any tool used for measuring moisture can be put to good use.