Buying a down duvet - The big guide

Anyone looking to buy a new duvet will quickly come across many technical terms: fill power , filling weight , 90% down , 10% feather …
But what do these details actually mean – and what should you pay attention to when buying?
In this guide, we explain everything in simple language and help you find the perfect down duvet for your sleeping comfort.

1. Down vs. feathers – and why quality matters

• Down is the soft, three-dimensional feathers beneath the outer feathers of a goose or duck. It consists of many fine strands that trap air—perfect for warmth with minimal weight.
• Feathers are larger, flatter, and have a firm quill. They add volume, but are heavier and provide less insulation.

Quality classes for down and feathers

Not all down and feathers are the same. The quality depends on:

1. Animal species (goose or duck – goose is usually of higher quality)
2. Origin (colder regions → larger, denser down)
3. Age of the animals (older animals → fully developed, long-lasting down)
4. Processing (gentle washing, sorting and drying preserves bulk)

High-quality down is larger, fluffier, and more durable. Cheaper fillings often contain many broken feathers, smaller down pieces, or even debris, which significantly reduces comfort.

In the picture on the left, you can see Calmont's high-quality, even, soft feathers – voluminous, elastic, and with fine fiber branches that optimally trap air.
On the right, however, you can see a competitor's low-quality nib —with many broken quills, smaller fragments, and less volume. These feel harder, lose their shape more quickly, and insulate less effectively.

Conclusion: Quality can be seen and felt – and it determines how warm, light, and durable your blanket or pillow really is.

2. The loft – the measure of warmth with little weight

Fill power indicates how much down and feathers can fluff up. The higher the number, the more air is trapped—and the better the duvet or pillow keeps you warm without being heavy.

• Below 500 = basic quality, often with many broken feathers, impurities and less volume.
• 600–700 = good to very good quality, pleasantly warm with moderate weight.
• 700+ = Premium quality, maximum comfort with minimal weight. 

In general, a higher fill power also ensures the typical voluminous fluffiness of down duvets and pillows – they appear fluffier, recover more quickly after being compressed, and retain their shape for many years.

Important: A higher fill weight does not guarantee better warmth. High-quality down with a high fill power often provides better warmth with less weight – and also feels softer and more cuddly. Image comparison: Left: Standard "Made in Germany" pillow – Right: Calmont down pillow with high filling power

On the left in the picture you can see a 3-chamber down pillow from a German manufacturer with lower, impure feather quality and a higher filling weight.
On the right is our Calmont 3-chamber down pillow : significantly lower filling weight , but much higher down and feather quality as well as superior fill power .
The result: more loft, better air retention and noticeably greater sleeping comfort – all without unnecessary heaviness.

3. Filling weight – not necessarily warmer

Many people think: “The heavier, the warmer.”
This is only true if the filling quality is identical. In practice, a higher weight often doesn't mean more warmth , but simply more mass —especially with inferior feathers or down.

Why less weight is often better

• High-quality down with high fill power can trap more air and therefore insulate better.
  → Result: Same or higher heat output with significantly less weight.
• Lighter blankets and pillows fit better to the body without creating pressure, thus improving sleeping comfort.
• Significantly better moisture regulation : Less material also means that moisture can escape more quickly – important for a dry, comfortable sleeping environment.

Practical example

A standard down duvet with 400–450 g/m² can have the same warmth as a Calmont premium down duvet with “only” 280 g/m² – the difference lies in the quality and loft of the filling, not in the sheer weight.

Remember: When buying, don't just look at the weight, but also at the combination of filling weight , down content and fill power .

4. Reference material

The cover material of a down duvet or pillow is much more than just the outer shell.
It protects the filling, influences sleeping comfort and ensures that down and feathers retain their shape for many years.

Important characteristics of a good cover:

• Downproof : Finely woven to prevent down or feathers from escaping while preventing mites or dust particles from easily penetrating.
• Breathable : Supports moisture exchange and prevents heat build-up.
• Skin-friendly : Soft, comfortable feel that feels good even without bedding.

Please note: One of the great advantages of a high-quality down duvet is its high level of warmth combined with exceptional breathability. This advantage should not be compromised by choosing an inferior material for the cover.

Fabric types

• Percale : Matte, strong cotton fabric, very breathable and robust – ideal for long-lasting everyday blankets.
• Satin : Smooth, silky cotton fabric with a slight sheen, particularly soft and flattering to the skin.
• Fustian/Flannel : Slightly roughened, warm and cozy, especially for winter blankets.

Thread Count (TC)

The thread count describes how many threads are woven per square inch of fabric.

• 200–300 TC : Good everyday suitability, durable and breathable.
• 300–500 TC : Very tightly woven, particularly soft and luxurious.

Tip: A tightly woven cover is more durable and prevents down or feathers from poking through the fabric—crucial for comfort and durability.

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5. Find the right size:

Single or double duvet? This question is especially relevant for couples.

The answer to this lies in the sleep needs of both partners.

Do you prefer to sleep warm, but your partner is usually too warm? We recommend choosing two single duvets to perfectly meet your individual sleeping needs.

Or would you rather benefit from your partner's pleasant warmth and enjoy a shared cuddle experience? A large double duvet is more suitable in this case.

The following rules of thumb have proven successful for our customers:

·      The 180cm rule: For those over 180cm tall, we recommend choosing an extra length of 220cm.

·      Be generous with double duvets: Especially with duvets for double beds, it is recommended to choose sizes that extend generously over the edges of the bed to guarantee optimal thermal insulation.

·      If in doubt, choose the larger of the two options.

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6. Seasons & heat classes

Down duvets are available in different warmth classes , depending on your personal warmth needs and the season:

• Summer blanket (grades 1–2)
  Very light, low filling capacity, perfect for warm summer nights or heated bedrooms.
• All-season duvet (class 3-4)
  Medium capacity, ideal for year-round use in well-insulated homes.
• Winter blanket (grades 5–6)
  Higher filling capacity, extra warm, ideal for cool bedrooms or those with frostbite.
• 4-season blanket
  Two separate blankets (usually summer + all-season blanket) that can be buttoned together for winter – maximum flexibility.

Tip: With premium down, a lighter warmth rating can often provide the same comfort as a heavier standard duvet.

7. What should I look for when buying?

1. Down content : 60% down or more for good sleeping comfort.
2. Fluffiness : 700+ for light and warm.
3. Cover material : tightly woven, preferably cotton percale or satin for a skin-friendly feel.
4. Certificates : Pay attention to animal-friendly origins (e.g. DownPass certified).
5. Suitable warmth class : Choose according to the season and personal warmth sensitivity.

8. Care instructions for down duvets

A high-quality down duvet will last for many years – often even decades – if properly cared for.

• Ventilation : Shake regularly and ventilate in the fresh air (not in direct sunlight).
• Washing : Depending on the manufacturer, washable every 1–3 years, ideally at 40°C or 60°C with down detergent .
• Drying : Be sure to tumble dry with tennis balls or dryer balls to fluff up the down.
• Change cover : Change bed linen weekly or every two weeks to keep the duvet clean.
• Storage : In summer, store in a breathable bag or cotton sack (included with Calmont) – never in plastic, as this will trap moisture.

9. Which down duvet is right for you?

At Calmont, we offer various models – from the affordable entry-level model to the luxurious Royal Edition:

• 10EN duvet – robust blend, ideal for guest rooms or as a transitional duvet.
• Comfort 60EN down duvet – good warmth at a fair price, perfect all-rounder.
• Premium 90EN down duvet – premium quality for high sleeping comfort, warm and feather-light.
• Royal Edition – 100% goose down, satin cover, 700+ fill power – The Rolls Royce of down comforters and our luxury model for discerning sleepers.

10. Conclusion

If you want to buy a down duvet , you should not just look at the weight.
The quality of the down (fill power) and processing are crucial for warmth, lightness and durability.
With the right model, you'll sleep at a comfortable temperature all year round – and wake up refreshed.

Tip: Discover our down duvet collection now and find your perfect model – from all-rounders to luxury for the cold winter months.