Gas Struts 250N vs 320N vs 380N: The Right Force for Cabinet Flap Doors

The force of a gas strut is measured in Newtons (N); 10 N corresponds to a lifting force of approximately one kilogram at the mounting point, which is why a 250 N version is designed for standard medium-sized flap doors, whilst 320 N and 380 N variants are engineered exclusively for heavy solid wood or glass fronts.

Introduction: When is choosing the right force critical?

When constructing or repairing wall units with upward-opening flaps, the gas strut is the central mechanical component. It performs two key tasks: it assists in opening the flap against gravity and holds it securely in the open position.

Selecting the exact force in Newtons is a critical factor in furniture installation. If the spring force is insufficient, the cabinet flap will drop back down after opening. If it is too strong, closing the flap requires significant physical effort. An overly powerful gas spring acts like a set bear trap – it jerks the front upward uncontrollably and exerts permanent, damaging tension on the concealed hinges and the cabinet carcass. This inevitably causes hinges to tear out of the chipboard. Therefore, the spring force must be precisely matched to the weight and leverage of the respective front.

What do 250 N, 320 N, and 380 N mean for gas struts?

Gas struts, also known technically as gas lift stays, consist of a cylinder and a piston rod. The cylinder is filled with nitrogen gas under high pressure. The rating in Newtons (N) defines the pushing force of the piston rod.

Important for fitters: A gas strut is not a standard furniture damper. Whilst a soft-close damper reduces closing speed, a gas strut generates active extension force. Modern flap stays use these cylinders to actuate the stay's lever arm.

• 250 N: Generates a pushing force of approx. 25 kg directly at the piston. Taking the stay's leverage into account, this is suitable for front weights of roughly 4 kg - 6 kg (depending on flap height).
• 320 N: Generates a pushing force of approx. 32 kg. Designed for front weights of approx. 6 kg - 8 kg.
• 380 N: Generates a pushing force of approx. 38 kg. Engineered for front weights of approx. 8 kg - 10 kg.

Beyond technical function, appearance also matters for open shelving units or glazed cabinets. The cylinders can be selected to match the carcass finish, such as silver gas struts for technical designs, black gas struts for dark MDF fronts, or white gas struts for classic kitchen wall cabinets.

The differences in detail: 250 N vs 320 N vs 380 N

The external dimensions of these three strength classes are identical in standardised fittings. The overall length when fully extended (centre of eyelet to centre of eyelet) is usually 245 mm - 247 mm. The stroke (the travel distance of the piston rod) is typically 90 mm. The sole, yet decisive difference lies in the internal pressure of the cylinder.

• 250 N application area:
• Material: Standard kitchen fronts made of melamine-faced chipboard (thickness 16 mm - 18 mm).
• Dimensions: Flap heights of 300 mm - 400 mm with a width of up to 600 mm.
• Typical application: Wall units above an extractor hood or cabinets concealing a wall unit dish drying rack.
• 320 N application area:
• Material: Heavier MDF (19 mm - 22 mm), fronts with applied mirrors, or light aluminium frames with glass inserts.
• Dimensions: Flap heights of 400 mm - 500 mm with a width of 600 mm - 800 mm.
• Typical application: Large living room wall units or tall bathroom cabinets.
• 380 N application area:
• Material: Solid wood (oak, beech), heavy double-glazed fronts, or very wide MDF panels.
• Dimensions: Flap heights exceeding 500 mm or widths of 900 mm - 1000 mm.
• Typical application: Heavy-duty gas struts are used on large-format flaps covering an entire upper kitchen section.

Which gas strut should you choose for your application?

The choice between 250 N, 320 N, and 380 N must never be made on the assumption that more is always better.

Choose 250 N when replacing a defective strut in a standard domestic kitchen. You will usually find a rating printed on the old part (e.g. 250N or 25kg). This strength is the standard benchmark for 80% of all domestic wall units.

Opt for 320 N if you are a joiner planning a bespoke build where the material is denser and heavier than standard chipboard. Upgrading to 320 N is also sensible if an existing 250 N spring no longer holds the flap open at the required angle (usually 95° or 110°) due to the subsequent fitting of a heavy handle.

Reserve 380 N strictly for genuinely heavy installations. If you are fitting a solid oak flap, a standard strut is not sufficient. In this scenario, you require heavy-duty lid stays and hinges engineered to withstand these tensile loads.

Calculating the required spring force

To determine the precise force required, calculate the door front weight.

• Formula for weight: `Width (m) × Height (m) × Thickness (m) × Density (kg/m³)`
• Typical material densities: Chipboard approx. 650 kg/m³, MDF approx. 750 kg/m³, glass approx. 2500 kg/m³.
• Add the weight of the furniture handle (often 0.1 kg - 0.3 kg).

Important installation rule: For flap widths of 450 mm and above, always use two gas struts (left and right). This prevents unilateral warping of the front. The total required force is then divided equally between both struts. For example, if a front requires 500 N of total force, install two 250 N struts.

Installation and replacement

Replacing a defective gas strut requires no specialist tools. Most models feature a clip-on mounting system.

1. Open the flap completely and support it securely (using an assistant).
2. Release the retaining clip on the ball joint of the old strut using a flat-head screwdriver.
3. Pull the strut away from the ball stud.
4. Press the new strut onto the ball studs until it audibly clicks into place.
5. Pay attention to the mounting orientation: the thicker cylinder section typically points upward towards the cabinet carcass, whilst the thin piston rod points downward towards the flap. This ensures continuous lubrication of the internal seals.

If mounting brackets need to be rescrewed, use chipboard screws with PZ or TX drive (Ø 3.5 mm or 4 mm). Pre-drilling with a 3 mm drill bit prevents splitting the wood grain.

Frequently Asked Questions (FAQ)

Can I replace a 250 N gas strut with a 380 N strut?

No, unless you have significantly increased the weight of the flap (for instance, by adding a mirrored panel). Fitting a 380 N strut to a light 4 kg flap makes it exceptionally difficult to close. Furthermore, the immense opposing force risks tearing the concealed hinges straight out of the carcass.

How do I measure the length of a gas strut correctly?

The relevant dimension is measured when the strut is fully extended. Measure from the centre of the top mounting eyelet (screw hole or ball socket) to the centre of the bottom mounting eyelet. The standard measurement in furniture construction usually ranges between 245 mm and 270 mm.

Why does a gas strut lose its force after several years?

Gas struts are wearing parts. The cylinder contains nitrogen gas stored under high pressure. Over thousands of operating cycles and temperature changes, the internal rubber micro-seals degrade. As minute amounts of gas escape, the extension force drops. Furniture gas struts cannot be repaired or refilled; the component must be replaced entirely.

What happens if I only install a strut on one side?

On very narrow cabinets (under 400 mm wide), a single strut is technically sufficient. On wider flaps, a single strut introduces asymmetrical force. The flap will twist upon closing, reveal gaps will become uneven, and the hinge on the strut side will wear out drastically faster.