What Do Garage Door Extension Spring Size Charts Actually Tell You?

Your garage door spring is broken, and a size chart seems like the simple answer. But using the wrong spring can make your door unsafe, damage your opener, or even cause a catastrophic failure.

A garage door extension spring size chart is a reference tool that matches the weight of your garage door to a specific spring, which is identified by its color code and length. It is designed to help you find an accurate replacement for your existing springs.

I've been manufacturing springs for over 14 let, and I can tell you that garage door springs are some of the most dangerous products we make. They operate under extreme tension, holding hundreds of pounds of force just inches above your head. A size chart is a good starting point, but it's not a magic solution. I once had a frantic call from a homeowner who had used a chart to replace his springs. He'd matched the color, but the door still wouldn't open correctly. It turned out his door was a custom-built wood door that was much heavier than standard. The chart he used was for steel doors. This is why just looking at a chart is not enough—you have to understand what the numbers actually mean.

How Do You Find Your Garage Door's True Weight?

You think your door weighs about 150 liber, but guessing is a huge mistake. The wrong guess leads to installing a spring that's either too weak to hold the door, creating a serious safety hazard, or too strong, which will damage your opener.

You must weigh the door to get an accurate measurement. The only safe and reliable method is to disengage the opener and the old springs, then weigh the door[^1] itself using two standard bathroom scales.

This is the single most important step, and it's the one people most often skip. They measure the old spring or look for a part number, assuming the last person installed the correct one. I've seen situations where the previous owner added insulation or even a new layer of wood paneling to a door, adding 30 nebo 40 pounds of weight. The old springs were already undersized and struggling. If you just replace them with the same size, you are setting yourself up for failure. Weighing the door is the only way to know for sure what you are dealing with. It removes all the guesswork and is the foundation for a safe repair.

The Weighing Process: A Critical Safety Step

Accuracy here prevents accidents later.

• Safety First: Before you do anything, you must disengage the electric garage door opener. Pull the red emergency release cord. Další, and this is the most dangerous part, you must carefully unhook the old extension springs while the door is in the UP position. If you are not 100% confident in how to do this safely, stop and call a professional.
• Using Scales: With the springs disconnected, lower the door. Place one bathroom scale under the left edge and one under the right edge. You may need to prop them up on small wood blocks to get them under the door seal.
• The Calculation: Let the door rest fully on the two scales. Add the reading from the left scale to the reading from the right scale. This total is the true weight of your garage door. This is the number you will use to find the correct spring on the size chart.

What Do the Color Codes on Garage Door Springs Mean?

You see a color on your old spring, but what does it actually represent? Just matching the color isn't always enough, especially if the previous spring was incorrect or the door's weight has changed over time.

The color code[^2] is a simple industry standard for identifying the lifting power of a spring. Each color corresponds to a specific door weight, usually in 10-pound increments. Například, a Gold spring is designed to lift 110 liber, while a White spring is for 120 liber.

The color code[^2] system was created to make identification fast and easy for professional installers. It's a great system, but it relies on the first principle we just discussed: you have to know the actual weight of the door. I once consulted with a garage door installation company that was having a lot of service callbacks. It turned out their new apprentice was just replacing springs by matching the color of the old one. He wasn't weighing the doors. After we implemented a strict "weigh every door, every time" policy, their callback rate dropped by over 80%. The color is just a label; the weight is the reality.

A Typical Garage Door Spring Color Chart

This chart is for springs used on a standard 7-foot tall garage door.

• The 10-Pound System: The colors change for every 10 pounds of door weight. This allows for precise balancing of the door.
• Double Springs: Remember, these ratings are for a pair of springs. A 140-pound door doesn't use one 140-pound spring. It uses two 140-pound rated springs (Green), one on each side, because each spring is only responsible for lifting half of the total door weight.
• Length is Also Key: The standard length for springs on a 7-foot door is 25 palce. They are designed to stretch to 42 palce. Using a spring that is too long or too short will prevent the door from working correctly, even if the color code[^2] is right.

Why Does My 8-Foot Door Need a Different Spring Chart?

You have a taller 8-foot garage door, and you used the standard chart. Now the new springs are overstretched when the door is open, and they don't have enough power to close the door properly.

An 8-foot door requires a longer spring. Because the door is taller, the spring has to stretch a greater distance. A standard 25-inch spring would be stretched beyond its limit. Springs for 8-foot doors are typically 27 inches long and follow a different color chart.

This is a detail that causes a lot of confusion. A customer ordered a pair of 150-pound (Blue) springs from us. A few days later he called, angry because they "weren't strong enough." After a few questions, I asked him to measure the height of his door opening. It was 8 feet tall. He had installed 25-inch springs on an 8-foot door. When the door was fully open, the springs were stretched so far that they had lost their power and were permanently damaged. We sent him the correct 27-inch springs, and the door worked perfectly. It's a reminder that the entire system—door height, cable length, and spring length—has to work together.

Sizing for Taller Doors

The mechanics change with a taller door.

• Increased Travel: An 8-foot door has to travel an extra 12 inches compared to a 7-foot door. This means the cables attached to the spring also have to travel further.
• Longer Springs Needed: To accommodate this extra travel without being overstretched, the spring itself must be longer. A 27-inch spring is standard for an 8-foot door. It has more coils and is designed for a longer stretch.
• Different Color Chart: Because the spring's physical design is different (more coils, longer wire), the color code[^2] ratings also change. A 150-pound spring for an 8-foot door might have a different color than a 150-pound spring for a 7-foot door. You must use a chart that is specifically for 8-foot doors.

Závěr

A garage door spring size chart is a vital tool, but only when used correctly. Always weigh your door first, then use that weight and your door's height to find the right color code[^2].

[^1]: Accurate weighing is the first step in ensuring you select the right spring, eliminating guesswork.
[^2]: The color code helps identify the lifting power of springs, making it easier to select the right one for your door.