Calculating Gas Struts: How Many Newtons (N) Does Your Cabinet Flap Need?

A gas strut assists with opening furniture flaps, holds them securely in the open position, and requires an exact calculation of pushing force in Newtons for flawless operation.

Selecting the right fitting for an upward-opening cabinet flap is a task of technical precision. The mechanism functions just like the tailgate on a car: if the rating is too low, the flap falls down uncontrollably. If it is too strong, the cabinet can only be closed with huge effort, which will tear the hinges out of the carcase over time. For joiners, fitters, and skilled DIY enthusiasts, it is essential to know the physical parameters of the flap before installation begins.

In this buying guide, you will learn the criteria used to calculate the required force, which designs are available, and how to position the components correctly inside the cabinet carcase.

The Most Important Buying Criteria for Gas Struts

Before deciding on specific flap fittings, three fundamental parameters of the cabinet must be determined. These values form the basis for every subsequent calculation.

• Flap weight: The absolute weight of the front in kilograms. The base weight of the material must include the weight of the furniture handle.
• Flap height: The vertical dimension of the front in millimetres. The height determines the lever arm. At the same weight, a tall flap requires significantly more force than a low flap because the centre of gravity is situated further away from the pivot point (the hinge).
• Opening angle: Depending on ceiling height and accessibility, flaps are usually opened to 75°, 90°, or 110°. The desired angle defines the exact drilling distances in the carcase and on the front.

How Do You Calculate the Required Force in Newtons (N)?

The extension force of a gas spring is specified in Newtons (N). As a rough rule of thumb: 10 N corresponds to a lifting force of around 1 kg. However, because the force does not act vertically but through a lever angle, this simple conversion is not sufficient for cabinet making.

Method 1: Weighing the Front Directly

Dismantle the front, including the handle, and weigh it on precise scales. Based on the weight and flap height (typically between 300 mm and 500 mm for standard wall units), the following guide values apply for a 90° opening angle:

• Up to 1.5 kg: 50 N (or 2x 40 N)
• 1.5 kg - 2.5 kg: 60 N to 80 N
• 2.5 kg - 3.5 kg: 100 N to 120 N
• 3.5 kg - 4.5 kg: 150 N
• Over 4.5 kg: In this case, gas struts for heavy flaps from 200 N upwards are strictly required.

Method 2: Calculating Weight via Volume

If the front has not yet been cut, the weight can be calculated theoretically using the density of the material. The formula is: length (m) × width (m) × thickness (m) × density (kg/m³).

Typical density values in cabinet making:

• Chipboard (melamine-faced): approx. 650 kg/m³
• MDF (medium-density fibreboard): approx. 750 kg/m³
• Solid wood (e.g. oak): approx. 700 kg/m³ to 800 kg/m³

A calculation example for an MDF flap measuring 600 mm in width, 400 mm in height, and 19 mm in thickness: 0.6 m × 0.4 m × 0.019 m = 0.00456 m³. Multiplied by 750 kg/m³, this gives a bare panel weight of 3.42 kg. Adding a solid stainless steel handle of 0.3 kg brings the total weight to around 3.7 kg. For this scenario, you need a total force of at least 120 N to 150 N.

Overview of Types and Options

The range of hardware for furniture flaps is diverse. In addition to pure force in Newtons, the build style and visual integration into the carcase play an important role.

Standard vs Heavy-Duty Design

For conventional kitchen wall units, standard models are usually sufficient. However, if you are planning a living room storage unit where wide solid wood fronts open upwards, standard struts reach their limits. This is where heavy-duty variants come into play, featuring a thicker cylinder diameter and handling ratings of 200 N, 250 N, or more.

Visual Adaptation to the Furniture Design

In modern furniture construction, the interior of the carcase is increasingly incorporated into the overall design. A gas strut does not necessarily have to look like industrial metal.

• For light carcases made of white chipboard or with light maple decor, white gas struts blend in almost invisibly.
• In dark kitchens (e.g. anthracite or matt black), black gas struts provide a discreet appearance when the flap is opened.
• For technical designs or classic wood decors, the silver gas strut remains the proven standard.

Differences from Other Flap Fittings

Do not confuse gas springs with mechanical lid stays. A classic flap stay often works purely on friction (braking force), which is adjusted manually via a screw. It does not actively assist opening via gas pressure, but merely holds the flap in position. Furthermore, gas struts are completely different from a soft-close buffer. While the spring pushes the flap upwards, a soft-close component cushions the closing movement of doors or drawer runners.

Which Strut for Which Case? (Selection Guide)

To ensure a safe and durable installation, refer to the following application scenarios:

• If you are fitting a standard kitchen flap (MDF, 400 mm high), then use two struts rated at 60 N each. Installing fittings on both sides prevents the front from warping over time.
• If you are planning a small, light flap above a microwave or cooker hood (height approx. 250 mm), then a lighter 50 N model is often sufficient.
• If you are equipping a very wide and heavy flap (e.g. 1000 mm wide, solid wood), then choose two heavy-duty struts rated at 150 N to 200 N. Make sure to use at least three to four concealed hinges along the top edge, as the strut pressure exerts significant force on the hinges when closed.

Installation Notes and Fitting

Correct positioning of the fixing points is essential. A deviation of just 5 mm drastically changes the lever travel, causing the flap to either not open fully or fail to close properly.

Required Tools

• Tape measure or folding rule
• Bradawl
• Cordless screwdriver with suitable bit (usually PZ2)
• Wood drill bit (Ø 2 mm for pilot holes)

Installation in 4 Steps

1. Transfer measurements: Take the exact drilling dimensions (X and Y axis) from the manufacturer diagram. The dimensions vary depending on the chosen opening angle (75°, 90°, 110°). Always measure from the front inner edge of the carcase.
2. Pre-drill: Mark the points using the bradawl. With chipboard, it is advisable to drill a minimal pilot hole with a 2 mm bit to prevent the melamine coating from tearing out when driving in the chipboard screws.
3. Screw on brackets: First attach the round mounting plate to the inside of the carcase, followed by the elongated bracket on the inside of the flap.
4. Clip on the strut: Push the socket heads of the gas spring onto the ball studs of the brackets until they click audibly into place. Important: As a rule, install the strut so that the thick cylinder points upwards and the thin piston rod points downwards. This ensures that the internal oil lubricates the seals and end-position damping operates properly during opening.

Frequently Asked Questions (FAQ)

Can I install only one gas strut per flap? Technically, this is possible on very small and light flaps (under 300 mm wide). For standard dimensions, however, this is strongly discouraged. Pressure applied to one side causes the flap to twist over time, preventing it from sitting flush against the carcase. Always install two struts.

Why is my flap almost impossible to close after installation? In this case, the Newton (N) rating is too high for the weight of your flap. If a light 2 kg front is fitted with two 100 N struts (designed for around 20 kg of lifting force), the manual effort required to close it is excessive. Replace the struts with 50 N or 60 N models.

Why does the flap not open to the desired angle? This is usually caused by incorrectly positioned drill holes. If the carcase measurement is placed too far back or the flap bracket is set too low, the stroke (the extension travel of the piston rod) will not be sufficient to open the flap fully. Check your mounting distances against the manufacturer specifications.

Are gas springs compatible with push-to-open mechanisms? Only to an extent. A gas spring pushes the flap open once it has passed a specific initial angle. For handleless fronts, you will need sprung hinges without catch mechanisms (free-swinging) and a strong push-to-open piston that pushes the flap out far enough for the gas strut to take over.

How do I release a fitted strut from the bracket? The ball heads of the struts typically feature a small metal clip. Slide a flat-head screwdriver under this clip and lever it up slightly. This expands the internal retainer, allowing you to pull the strut off the ball stud without force.

Suitable Hardware Products and Categories

To find the matching hardware components for your next furniture project, browse directly through the specialised categories for flap systems:

• Explore all solutions for upward-opening fronts under flap fittings.
• Find standard versions in various force ratings within the gas struts section.
• For solid fronts and high weight capacities, choose gas struts for heavy flaps.
• Discover mechanical options without gas pressure in the flap stays range.
• Match the colour of the hardware to your carcase: discover silver gas struts, black gas struts, or discreet white gas struts.