Does your door slam shut? Choose the right gas strut in seconds! Is your storage bed too heavy? Or does your kitchen cabinet door always fall on your head? Using the wrong gas strut not only wastes your money but can also break the hinges. Our Smart Gas Strut Calculator will tell you the exact force (in Newtons) and mounting positions, so every door opens and closes smoothly, like butter.

Whether you’re a DIY enthusiast building a camper van conversion, a woodworker creating custom cabinetry, or a professional installing hatches on boats or machinery, using a gas strut calculator ensures your setup is safe, smooth, and long-lasting. Let’s get started!

What Are Gas Struts? (The Muscle Behind Your Furniture)

Gas struts are mechanical devices that store energy by compressing high-pressure nitrogen gas inside a sealed cylinder. When you open a lid or door, this gas expands and pushes a piston rod outwards, providing lifting support.

In simple terms: It’s the “invisible muscle” that makes it possible to lift even heavy storage beds or cabinet doors with just one finger. It also contains a small amount of oil that keeps the movement smooth and provides damping (shock absorption) at the end of the stroke.

Why Do You Need a Gas Strut Calculator? (Don’t Guess, Calculate!)

Many DIYers and professionals make the mistake of buying struts “by guess.” Installing a gas strut without calculations is like buying shoes without checking the size.

Here are 3 major reasons why using a gas strut calculator is a sign of expertise:

Safety First (A Gentle Opening)

If you install a strut with too much force, the lid will open abruptly and could injure your face or chin. Conversely, if the force is too low, the heavy lid won’t stay open and could fall on your hand. The gas strut calculator tells you the exact Newton (N) rating you need.

Protecting Your Investment (Protecting the Hinges)

Incorrect mounting positions put so much torque (pressure) on the hinges that they can break prematurely or detach from the wood. A gas strut calculator helps you by providing the perfect mounting points where the balance is optimal.

Professional Finish & Durability

With the correct calculations, your strut won’t “bottom out,” meaning it won’t get stuck when closing. A gas strut calculator ensures that the strut’s stroke length and extended length match your furniture frame, significantly extending the strut’s lifespan to 5-10 years or even more.

Expert Tip: Whether you’re a DIY enthusiast or a professional cabinet maker, for the best results, always consider the Safety Factor (1.5x) and Rod-Down Orientation. Our gas strut calculator is designed to take all these technical details into account.

How an Gas Strut Calculator Works: The Simple Formula

Gas strut calculations are somewhat technical because they involve the principle of torque (rotational force). The main engineering formula behind this gas strut calculator is explained in detail below:

Basic Torque Balance Formula

Two types of forces act at the hinge point: the weight of the lid, which pulls it downwards, and the force of the gas strut, which pushes it upwards.

Here’s what everything means:

• $F$ (Force): The required force for each source (in Newtons).
• $W$ (Weight): The total weight of the lid in Newtons $(kg ×9.81)$.
• $L$_cg (Distance to CoG): The distance from the hinge to the center of gravity of the lid.
• $S$ (Safety Factor): The value you selected (1.1, 1.2, or 1.5).
• $n$ (Number of struts): The number of struts (1 or 2).
• $d$ (Mounting distance): The distance from the hinge to the point where the strut will attach to the lid.
• $sin(θ)$: Lid opening angle (open angle).
• $1.15$: This is an extra margin that is added to account for real-world friction and temperature changes.

Length and stroke calculation

“Geometry rules” are used to calculate the length and stroke:

• Extended Length ($L$_ext): This is calculated based on the total height of the lid and the opening angle, so that the lid can open completely.

• Stroke ($L$_s): The length of the road leading into the culvert. Typically, this is 45% of the total length to prevent the culvert from “bottoming out” (i.e., getting stuck) when it’s closed.

Mounting Position Logic

The closer the mounting point is to the hinge, the stronger the strut ($N$) will need to be. Therefore, we recommend that the mounting point ($d$) always be between 20% and 30% of the total depth of the lid.

Example: If your lid weighs 20 kg and you mount the strut very close to the hinge, you might need an 800N strut due to the torque. However, if you move it slightly further away, a 400N strut will suffice.

Example 1: Heavy Kitchen Cabinet (Vertical Door)

Imagine you have a heavy kitchen cabinet with a door that opens upwards.

Inputs:

• Lid Weight: 5 kg
• Lid Depth: 400 mm (0.4 m)
• Center of Gravity (CoG): 50% (0.2 m from the hinge)
• Number of Struts: 2
• Mounting Position: 25% (0.1 m from the hinge)
• Safety Factor: 1.2
• Angle: $90°(sin(90°)=1)$

Calculation:

1. Weight in Newtons: $5×9.81=49.05N$
2. Torque (Lid): $49.05×0.2m=9.81Nm$
3. Force Required (Total): $9.81Nm/0.1m×1×1.2(safety)×1.15(Fraction)=135.37N$
4. Per Strut Force: $135.37÷2≈68N$

Result: You should buy two struts from the market for 80 (rounded up).

Example 2: Storage Bed (Heavy Mattress)

The calculation in B.Ed. involves a lot of weight, so the force will also increase here.

Inputs:

• Bed Frame + Mattress Weight: 60 kg
• Bed Length: 1800 mm (1.8 m)
• Center of Gravity (CoG): 50% (0.9 m hinge se)
• Number of Struts: 2
• Mounting Position: 20% (0.36 m hinge se)
• Safety Factor: 1.5
• Angle: 45° $(sin(45°)≈0.707$ – Because the bed often doesn’t open completely to a 90° angle.

Calculation:

1. Weight in Newtons: $60×9.81=588.6N$
2. Torque (Bed): $588.6×0.9m=529.74Nm$
3. Force Required (Total): $529.74Nm/0.36m×0.7.7×1.5×1.15=3585.5N$
4. Per Strut Force: $3585.5÷2≈1792N$

Result: You will need heavy-duty struts with a rating of 1800N or higher.

Important Point (Don’t Forget!):

In both of these examples, you will have noticed that:

• In Example 1, the mounting was at 25%, so less force was required.
• In Example 2, the bed was heavy and the mounting was close to the hinge (20%), so the force increased significantly (into the thousands).

If you increase the mounting point from 20% to 30% in Example 2, the force will decrease immediately, and this will reduce the load on the struts.

Gas Strut Installation: Common Mistakes to Avoid

Rod Up vs. Rod Down (Wrong Direction)

• This is the biggest and most common mistake. People often install the rod (the thinner side) facing upwards.
• Correct Method: When the lid is open, the rod should always be facing downwards.

Why? The oil inside the strut keeps the seals lubricated when the rod is facing downwards. If you install it the wrong way, the gas will leak, and the strut will fail prematurely.

Newton Force Misconception

People think that the more force, the better, but that’s not the case.

• Mistake: Installing a strut with too much force (N) can be a big mistake.
• Consequences: Your lid won’t close, the hinges will break, or the door will open with a jolt, which can be dangerous. Always choose a strut with a Newton value close to the one recommended by the gas strut calculator.

Mounting Point Drilling Mistake

Drilling the strut at an arbitrary location can be a big mistake.

• Mistake: Mounting it too close to or too far from the hinge.
• Correct Method: The gas strut calculator provides you with an exact distance (e.g., 200mm from the hinge). If you deviate from this, the door will either not open completely or will “jam” when closing.

Imbalance on Both Sides

If you are using two struts, their power and position should be exactly the same.

• Mistake: Using one old and one new strut, or having a difference in their mounting positions.
• Consequence: This can cause the lid to twist and put uneven load on the hinges.

Risk of “Bottoming out”

If your strut compresses completely inside the cylinder when closed, leaving no space at all, this is called “bottoming out.”

• Mistake: Choosing a strut with a stroke length shorter than the required movement.
• Consequence: This damages the internal valve of the strut. There should always be a small amount of stroke (≈ 10-20mm) remaining when the strut is fully compressed.

Pro Tips for a Successful Installation:

• Temporary Fitting: First, check the struts with clamps or temporary screws, then perform the final drilling.
• Hinge Strength: Ensure that your hinges are strong, as the main force of the gas strut is exerted on the hinges.
• Pair Replacement: If one strut fails, always replace both (the pair) to maintain force balance.

If you want to understand the force calculation, correct length selection, mounting position, and safety guidelines for gas struts (gas springs) in detail, this external website can be used as a trusted reference.

Frequently Asked Questions