What Size Gas Strut Do I Need? A Complete Guide for Getting It Right.

Gas Struts make lifting, lowering, and holding panels effortless, but choosing the wrong size can lead to doors that wont stay open, slam shut, or strain fittings. 

So how do you know what size gas strut you need? This guide breaks it down step by step so you can choose the perfect strut for your application.

Why Getting the Right Gas Strut Size Matters? Using the wrong gas strut size or force rating can cause: 

• Difficulty opening or closing lids
• Safety hazards from uncontrolled movement 
• Premature wear on hinges and fittings
• Reduced lifespan of your gas struts

Choosing correctly ensures smooth, safe, and reliable operation every time. 

First Step is Understanding Gas Strut Sizing

When people ask "what size gas strut do I need," they're usually referring to three key factors: 

1. EXTENDED LENGTH: the full length of the strut when fully open (centre of ball joint to centre)

2. COMPRESSED LENGTH: the length when fully closed

3. STROKE LENGTH: the distance the strut travels between open and closed positions

TIP: Always measure your existing strut if replacing one, as this ensures a perfect match.

Second Step is Choosing the Right Gas Strut Force (Newton Rating) 

The force of a gas strut is measured ing Newtons (N). Choosing the correct force rating depends on: 

1. WEIGHT OF THE LID OR PANEL 

2. MOUNTAIN POSITION OF THE STRUT 

3. ANGLE OF OPENING 

3. NUMBER OF STRUTS (usually 2) 

Simple Rule of Thumb

Light Panels: 40N-200N

Medium Lids (toolboxes, camper doors): 200N-600N

Heavy Applications (canopies, machinery): 600N +

Third Step, Measuring Your Application Properly 

To get the correct size gas strut, measure:

1. OPEN POSITION - Measure the distance between the mountain points when the lid is fully open. 

2. CLOSED POSITION - Measure the distance when fully closed

3. MOUNTING ANGLES - The angle impacts how much force is needed, steeper angles generally require less force.

Fourth Step Is Assessing Weight Placement and Load Points

The position of the weight matters just as much as the weight itself. 

A long lid with weight at the far end will need a stronger strut

A compact lid with central weight needs less force

For accuracy, calculate: Force Required = (Weight x Distance from hinge) ÷ Number of struts

Fifth Step Is Positioning the Gas Strut Correctly

Mounting position makes a big difference to performance. 

Closer to hinge = more force required 

Further from hinge = less force needed

Angle affects smoothness and control 

Correct positioning ensures: Smooth Opening, Stable Hold & Easy Closing

Sixth Step Is Deciding How the Lid Should Behave

Think about how you want your setup to feel: 

Self opening lid = higher force 

Controlled lift = balanced force

Easy closing = slightly lower force 

The goal is: Easy to open, stays open reliably, smooth & safe to close.

PRO Tips from TSF Direct

Install struts with the rod facing downward

Always replace struts in pairs

Avoid overpowered struts as they can damage hinges

Use marine grade struts for outdoor applications

 

Get it right, and you'll have smooth, reliable performance for years. 

 

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