How to Calculate the Required Force for Your Gas Spring

One of the most common questions we receive at DK Gas Spring is: "How strong does my gas spring need to be?"

If the force (F1) is too low, the lid won't stay open. If it's too high, you won't be able to close it. To get it just right, you need a bit of physics. Don't worry, we've simplified the formula for you.

The Key Variables

Before you start, you need to measure or estimate these 4 values:

1. G (Weight of the Lid): The total weight of the object you are lifting (in kg or N).
2. L (Length of the Lid): The distance from the hinge to the far edge (in mm).
3. W (Center of Gravity): The distance from the hinge to the lid's center of gravity (usually L / 2 for a uniform lid).
4. P (Mounting Point): The distance from the hinge to where the gas spring attaches to the lid (in mm).

The Formula

The basic formula to calculate the required force ($F_1$) for one gas spring is:

F1=GW/P1.1

• 1.1 is a safety factor (adding 10% extra force to ensure it holds firmly).
• If you are using two gas springs (one on each side), divide the result by 2.

Step-by-Step Example

Let's say you have a heavy wooden toy box lid:

• Weight (G): 10 kg (approx. 100 Newtons)
• Center of Gravity (W): 300 mm (half of the 600mm lid length)
• Mounting Point (P): 100 mm (you plan to mount the gas spring 100mm from the hinge)

Calculation:

1. Torque needed: G*W=30,000N.mm
2. Force per spring: 30,000N.mm / 100mm = 300N
3. Safety Factor:300N*1.1=330N

So, if you use one gas spring, you need a 330N strut. If you use two gas springs, you need 165N each (round up to standard 150N or 200N).

Tips for Success

1. Mounting Point (P): Moving the mounting point further from the hinge (increasing P) reduces the required force but requires a longer stroke gas spring.
2. Angle Matters: The formula above assumes the gas spring is perpendicular to the lid at the start. In reality, the angle changes. Our online calculator takes this into account for precision.
3. Hand Force: Remember, the user has to push down against this force to close the lid. A 500N spring requires roughly 50kg of force to compress directly (though leverage makes it easier). Don't over-spec!

Need Help?

Calculating force can be tricky for complex hinges or non-uniform lids.

• Contact Our Engineers: Send us your dimensions, and we will run a professional simulation for you to find the perfect mounting points and force.

---

Next Week: We’re heading to the high seas! Learn why 316 Stainless Steel is the only choice for marine gas springs.