1. Measure Your Environment: Use a thermometer and a hygrometer to get an accurate reading of the ambient temperature and relative humidity of your space.
2. Enter the Values: Input the temperature (in Fahrenheit) and the relative humidity (as a percentage) into the calculator.
3. Calculate EMC: The calculator will show the EMC percentage that a piece of wood will eventually acclimate to in that specific environment.
4. Acclimate Your Wood: Store your lumber in the target environment until its moisture content, measured with a moisture meter, matches the calculated EMC. This can take several weeks.

• Equilibrium Moisture Content (EMC): The moisture content at which wood is neither gaining nor losing moisture from the surrounding air.
• Relative Humidity (RH): The amount of water vapor present in the air, expressed as a percentage of the amount needed for saturation at the same temperature.
• Hygrometer: An instrument used to measure relative humidity.
• Acclimation: The process of allowing wood to sit in a new environment until its internal moisture content reaches equilibrium with the surroundings (EMC).
• Hygroscopic: The property of a substance (like wood) to attract and hold water molecules from the surrounding environment.

"Acclimation is not optional; it's a required step for any serious woodworking project. I tell my students to bring their wood into their shop at least two weeks before they plan to start. Stack it with 'stickers'—small pieces of wood—between each board to allow air to circulate freely on all six sides. This is the only way to ensure the wood is stable before you start milling." - Woodworking School Instructor

"Your goal is to build your project at the same moisture content it will have in its final home. A typical air-conditioned house in North America has an EMC of around 8-10%. A non-conditioned space in a humid climate could be 12-15%. Knowing the difference is critical."

Example 1: A Heated Workshop in Winter
Your workshop is heated to 65°F and a hygrometer reads the relative humidity at 35%.
The calculator shows the EMC for this environment is approximately 6.9%. You should let your lumber acclimate until it reaches this moisture level.

Example 2: A Humid Summer Garage
You're working in a garage during the summer. The temperature is 80°F and the RH is 70%.
The calculator shows the EMC is approximately 13.1%. If you build a cabinet in these conditions and then move it into an air-conditioned house (at ~8% EMC), the wood will shrink significantly, which could cause joints to fail or panels to crack.

• Not Acclimating Wood: The most common mistake, leading to projects that warp, twist, or tear themselves apart after they are built.
• Poor Air Circulation: Stacking wood flat on the floor or against a wall prevents air from reaching all surfaces, leading to uneven drying and acclimation.
• Ignoring Seasonal Changes: Building a project in a humid summer and not accounting for the dry conditions of a heated winter. Proper joint construction (e.g., frame and panel) is designed to accommodate this movement.
• Trusting the Lumberyard's "Kiln-Dried" Label: While wood may have been kiln-dried, it can re-absorb moisture during shipping and storage. Always measure the MC yourself when you get it to your shop.

• Fine Furniture Making: Ensuring wood is stable before cutting precise joinery.
• Cabinetry: Preventing doors and face frames from warping with seasonal changes.
• Hardwood Flooring Installation: Acclimating flooring to the home's environment before installation to prevent gapping or buckling.
• Shop Environment Control: Understanding if you need to use a humidifier or dehumidifier to maintain a stable environment for woodworking.