Have you ever followed a recipe to the letter, but when it came time to remove the dish from the oven, you found that it was significantly over- or undercooked? There could be several reasons for this—one being that your oven may need to be calibrated. Here’s how to do that on various types of oven.

Over time, the temperature you set your oven to using the controls may fall out-of-sync with its actual internal temperature. In other words, if you set it to bake at 350 degrees Fahrenheit, it may be getting hotter or colder than that inside the oven, affecting the outcome of the dish. Instrument Calibration Equipment

Before adjusting anything, do a quick test to see if your oven does, in fact, need to be calibrated. To do this:

Most ovens won’t be exactly on-the-nose: In fact, anything within 15 degrees of 350F is considered normal. But if your thermometer indicates that it was 335F or below, or 365F or above in your oven, it’s time to calibrate.

The calibration process will depend on a few different factors, including the brand of your oven, whether it’s gas or electric, and whether the controls are digital or analog.

The easiest way to find out to calibrate your oven is to check the owner’s manual. If you no longer have it, do a quick online search for your oven’s brand, make, and model, and you should be able to find a digital version of the manual. The manual will provide instructions for calibration, but for now, here’s a general overview:

The process will vary depending on the brand of the oven. For example, if you have a Whirlpool or Frigidaire oven , press and hold the “Bake” button until “Cal” appears. Then use the arrows to adjust the temperature, going up or down by 10-degree increments, based on whether your oven is running hot, or cold. So, if the test indicated that when you set your oven to 350F, it’s actually 370F inside, you’d hit the “down” arrow twice. Lastly, hit the “Enter” button.

Gently pull the knob or dial you use to adjust the oven’s temperature off the front of the oven. If you are having trouble, you can place a piece of string or wire around the back of the knob to help you pry it off.

There should be either one or two screws on the back of the dial: Turning these adjusts the oven’s internal temperature. Only turn the screw(s) 1/8 of a turn, going clockwise to decrease the temperature, and counterclockwise to increase it (the controls are very sensitive).

Then replace the dial, and run the thermometer test again. If the temperature is still off, go through the process again.

Portable Digital Thermometer Because gas is involved, this one is best left to professionals to ensure that everything is done safely.