Which skylight sizes are suitable for your situation?

A roof window is available in various standard sizes, ranging from compact formats for small spaces to large windows for maximum light. Choosing the right size depends on the function of the space, the roof pitch and the constructive possibilities of the roof. Correct measuring is essential to prevent leaks and extra construction costs.

1. Standard dimensions of roof windows

In the Netherlands, most manufacturers (such as Velux, Fakro and Roto) use fixed sizes. This often makes replacement possible without major carpentry work.

Please note: Dimensions are measured on the outside frame (not the glass size).

2. How to choose the right size?

• Small spaces (bathroom, storage room): small or medium-sized window, especially for ventilation.
• Average rooms (bedroom, study): standard size 78 × 118 cm for good light.
• Large open spaces (living room, loft): large to XXL window or multiple windows next to each other.
• Consider architectural limitations such as rafters or roof beams.

3. Roof pitch and size selection

• With steep roofs, a lower window is often sufficient for sufficient light.
• With a shallow slope, it is better to choose a higher window to allow more light in.

4. Measuring a roof window (existing situation)

Requirements: measuring tape, ladder/scaffolding, safety equipment.

1. Measure the width and height of the outside of the frame (not just the glass).
2. Note the exact measurement in centimeters.
3. Check the manufacturer's nameplate (inside of the window, usually on the side or top of the rotating part). This contains a code that allows you to directly find the correct replacement model.
4. Pay attention to obstacles inside and outside (sun protection, roof tiles, gutters).

5. Measuring for new placement

• Measure the available space between the roof rafters.
• Allow 2–3 cm of play for installation in the width.
• Take into account the roof pitch for optimal light incidence.
• Check whether a permit is required when changing the window size on the front of the house.

6. Cost indication per size (incl. VAT, excl. extra options)

Conclusion

Choosing the right roof window size starts with accurate measurement and matching the size to the need for light, ventilation and structural possibilities.

• Replacing an existing window? Use the outside dimensions of the frame or the factory code.
• Installing a new window? Consider rafters, roof pitch and permit requirements.

By comparing quotes via jeofferte.nl, you will find the best price and installation option for your desired roof window size.

In 2025, virtually all major roof window manufacturers such as Velux, Fakro and Roto will use fixed standard sizes. This makes it easier to replace a roof window without modifications to the roof and ensures clear price comparisons. The dimensions are always measured as the outside dimension of the frame, not the glass size.

1. Overview most common standard sizes

* Codes differ per manufacturer, but the principle is similar: first part = width class, second part = height class.

2. Why standard sizes are useful

• Simple replacement – Old roof window can be replaced 1-on-1 without extra carpentry.
• Price comparison – Standard sizes have fixed price ranges, easy to compare via jeofferte.nl.
• Wide availability – Available from almost every supplier, often directly in stock.
• Matching accessories – Sunshades, mosquito nets and roller shutters are standard available per size.

3. Measurement advice

• Always measure the outside dimension of the frame (width and height in cm).
• For existing windows, check the nameplate for the exact size code.
• Take into account the roof pitch: with a shallow pitch, a higher window gives more light.

Conclusion

Most roof windows fall within a range of 55 × 78 cm to 134 × 140 cm, with 78 × 118 cm being the most popular size in Dutch homes. By opting for a standard size, you benefit from lower costs, faster delivery, and a wide selection of accessories.

The price of a roof window strongly depends on the dimensions. Smaller windows are cheaper in material and installation, while larger windows give more light and view, but also require higher material costs and more installation time. Below you will find the average prices per standard size in 2025, including 21% VAT.

1. Average prices per size (incl. VAT)

2. What is included?

Price for window only:

• Standard version with HR++ glass.
• Basic finish (no extra sun protection or electrical operation).

Price incl. installation:

• Removal of old window (if present).
• Installation of new window, including connection set and waterproofing.
• Basic interior finishing.

3. Additional costs that may apply

• Special glass options (triple glazing, solar control, soundproofing): + € 50 – € 400.
• Operating options (electric, automatic): + € 300 – € 700.
• Sun protection or roller shutters: + € 50 – € 600.
• Scaffolding rental for hard-to-reach roofs: + € 100 – € 300.

Conclusion

In 2025, the price for a standard roof window will be between €500 and €1,800 including installation, depending on the size. Smaller windows are more affordable but let in less light, while larger windows require a higher investment but can increase living comfort and the value of the home.

Comparing multiple quotes via jeofferte.nl immediately shows which size and design offer the best value for money for your situation.

Although most manufacturers use similar standard sizes, the size coding differs per brand. This is especially important for replacement: the code on the nameplate determines which new model fits without adjustments to the roof. In 2025, Velux, Fakro and Roto have a large range of formats, ranging from compact windows to XXL versions.

1. Velux – standard sizes and codes

Velux uses two-letter width code + two-digit height code.
Example: MK06 = 78 cm wide × 118 cm high.

2. Fakro – Standard Sizes and Codes

Fakro uses a two-letter width code + two-digit height code, similar to Velux, but with its own letter assignment.
Example: FAKRO 78/118 = 78 cm wide × 118 cm high.

3. Roto – Standard sizes and codes

Roto works with width code + height code (usually 3 digits).
Example: Roto 7/11 = 74 cm wide × 118 cm high.

4. Important considerations when choosing a brand and size

• Not all codes are interchangeable: even with the same dimensions, the recess in the roof can differ per brand.
• Accessories (mosquito nets, awnings) are usually brand and size specific.
• When replacing it is always advisable to check the nameplate for exact size and product line.
• Some brands offer intermediate sizes for specific applications (e.g. narrow windows between rafters).

5. Comparison table (dimensions in cm)

Conclusion

In 2025, most skylight sizes at Velux, Fakro and Roto are largely comparable, but the size coding differs per brand. When replacing, it is essential to note the brand code so that you order a window that fits exactly without roof adjustments.

1. How long does a roof window last?

A well-installed roof window with quality glass and frame lasts on average 20 to 35 years, depending on the material:

• Wood: 20–25 years (with good maintenance).
• Plastic: 25–35 years.
• Aluminum: 35 years or longer.

2. Do I need a permit for a roof window?

• Back of the house: usually permit-free.
• Front or at monuments: often a permit is required.
  Always check with the municipality before ordering or having it installed.

3. What does a roof window cost including installation?

In 2025, the costs average between € 500 and € 1,800, depending on size, material and extra options.
A small model (55 × 78 cm) is cheaper, an XXL model (134 × 140 cm) is more expensive.

4. Can I install a roof window myself?

Technically, it is possible, but due to risks of leakage, fall hazard and warranty problems, it is strongly recommended to engage a certified installer.

5. What types of roof windows are there?

• Pivot windows – Rotating around the center, popular and affordable.
• Top-hung pivot windows – Hinged at the top, more view.
• Roof terrace or balcony windows – Luxurious solutions for extra outdoor space.
• Flat roof windows – Suitable for flat or slightly sloping roofs.

6. How much daylight does a roof window provide?

The rule of thumb: the glass surface should be approximately 10% of the floor area of the room for optimal light.

7. What extra options are recommended?

Popular extras in 2025:

• Sun protection (inside or outside).
• Insect screens.
• Electric operation.
• Triple or solar control glass.

8. How do I measure the correct size for replacement?

Measure the outside dimensions of the frame and check the size code on the nameplate of the current window.
This ensures that the new window fits without extra carpentry.

9. How do I maintain a roof window?

• Annual cleaning of glass, frame and hinges.
• Periodically paint or varnish wooden frames.
• Clean ventilation grilles for good air supply.

10. How quickly can a roof window be installed?

• Standard size: often installed within 1 day.
• Custom made: delivery time 2–6 weeks, depending on manufacturer.

Conclusion

With these answers, you have direct insight into the most important questions that play a role in the purchase or replacement of a roof window in 2025.
By comparing multiple quotes via jeofferte.nl, you can be sure that you are choosing the right price and quality.

Having a roof window installed is an investment that affects the living comfort, energy efficiency and appearance of your home. However, finding the right installer at a fair price can be time-consuming. Jeofferte.nl makes this process more efficient by quickly and clearly comparing multiple quotes from reliable professionals.

1. Access to a network of recognized professionals

• Jeofferte.nl only works with qualified and verified installers.
• Only professionals with demonstrable experience in roof windows and roofing work are eligible.
• Less risk of poor workmanship or hidden costs.

2. Transparent price comparison process

• Within a short time you will receive multiple quotes based on your wishes and situation.
• Easy comparison of price, materials, guarantees and planning.
• Prevents you from paying too much or choosing unnecessary options.

3. Saving in time and costs

• One request, multiple quotes – no endless calling and emailing with contractors.
• Due to competition between installers, prices are often 10–30% lower than with a direct request.
• Direct insight into the complete cost picture, including installation and extra options.

4. Better quality and warranty assurance

• Quotes contain clear specifications, so you know exactly what you get.
• Installers work according to applicable building and safety standards.
• Warranty on both the product and the installation, depending on the chosen professional.

5. Suitable for all types of roof windows and situations

• Suitable for replacing existing roof windows and new installation.
• For both pitched roofs, flat roofs and special solutions such as balcony windows or skylights.
• Possibility to directly include extra options (sun protection, shutters, electric operation).

6. Simple process in three steps

1. Submit request – Briefly enter your wishes (type of window, size, material, installation location).
2. Receive quotes – Within a short time you will receive offers from recognized installers.
3. Compare & choose – Select the best price-quality combination.

Conclusion

Having a roof window installed via jeofferte.nl means faster quotes, lower costs and more certainty about the quality. The platform takes the search work out of your hands, offers transparent comparison and ensures that you choose from experienced professionals who meet high quality standards.

As a result, you can be sure in 2025 that your roof window will not only be installed at the right price, but will also function reliably for years to come.