What is down fill power and fill weight for duvets?

Two Jars Comparing Down Fill Power & Down Fill Weight | scooms

Down fill power measures the quality and effectiveness of the loft or fluffiness of the down in a duvet. A higher fill power means the down duvet will be lighter and provide better insulation. Fill weight is the actual weight of the duvet filling. 

Down fill power vs fill weight key facts: 

  1. What is down fill power in a duvet?
  2. What is down fill weight in a duvet? 
  3. What is a scooms duvet's fill power?
  4. What is a scooms duvet's fill weight?
  5. scooms down cluster
  6. Fill power facts & myths




    What is down fill power in a duvet?

    Down fill power is a way to measure the quality and effectiveness of down in a duvet. The fluffier the down is, the greater the number of air chambers and therefore, the more effective the duvet is at insulating. So, a higher fill power means the down duvet will be both lighter and more insulating. A down duvet will also recover its fullness more easily with a daily shake and is proven to be more durable, so it will last longer.

    Duvet CUIN: Fill power is measured in CUIN which means 'cubic inches per ounce'.


    What is down fill weight in a duvet?

    Don't confuse fill weight with fill power! Fill weight is the actual weight of the duvet filling. The higher the fill weight, the heavier the duvet. However, a heavy duvet does not equal a warmer duvet.

    Fill weight determines how soft or firm a duvet is but, fill power measures the effectiveness and quality of the down or feather duvet filling. So, a duvet with high fill weight and low fill power will be heavy but provide poor insulation. 

    Fill weight meaning - If you see weight referenced with ‘gsm’ this means the weight of the filling within a square metre. 

    Our duvet gsm fill weights:

    • 9 tog duvet: 180gsm.
    • 4.5 tog duvet: 110gsm.
    • 2.5 tog duvet: 80gsm.


    What is a scooms duvet's fill power?

    scooms Hungarian goose down duvets have high 700 fill power. Technically called 700 CUIN fill power. 700 fill power is the highest fill power you can get for down that is a by-product of the food industry.


    What is a scooms duvet's fill weight?

    These are the fill weights for the different tog rated scooms duvets (not the total duvet weight).

    Duvet fill weight chart:

    * Single: 9 tog - 486g, 4.5 tog - 302g, 2.5 tog - 220g, All season - 788g 
    * Double: 9 tog - 720g, 4.5 tog - 448g, 2.5 tog - 320g, All season - 1168g 
    * King: 9 tog - 911g,  4.5 tog - 567g, 2.5 tog - 400g, All season - 1478g
    * Super King: 9 tog - 1030g, 4.5 tog - 641g, 2.5 tog - 480g, All season - 1671g

    If you're not sure what a tog rating is, then find out more in our Tog rating guide.


    Down cluster and down loft explained

    This is a close up view of a scooms Hungarian goose down cluster. The extra fine filaments trap more air giving our duvets a high fill power, which essentially means greater loft. This higher loft leads to a warmer and more breathable 'cloud like' duvet.


    Close Pp of a Down Cluster | scooms



    Duvet fill power guide - facts & myths

    True fill power facts:

    • The higher the fill power, the larger the clusters of down.
    • The higher the quality, the more durable the loft and fluffiness.
    • The larger the cluster of down the:
      • higher the quality
      • more air it traps.
      • higher the loft.
      • better the insulating properties.
      • larger the cluster of down, the lighter weight the duvet.

    Untrue fill power myths:

    • The higher the fill power, the:
      • firmer the duvet.
      • heavier the duvet.
      • higher the fill weight.

     Need to know more, see our Hungarian down duvet guide.




    What does fill power mean in down duvets?

    Down fill power is a way of measuring the quality and effectiveness of the down in a duvet. The fluffier the down is, the greater the number of air chambers and therefore, the more effective the duvet is at insulating. 

    What does 700 fill power in a down duvet mean?

    Fill power is calculated by measuring how many cubic inches of space an ounce of down takes up when the down clusters are fully expanded. 700 fill power means that one ounce of down fills 700 cubic inches of space.

    What is the highest fill power?

    700 CUIN fill power is the highest fill power for down that is a by-product of the food industry.

    Author: Emily AttwoodPublished: 20 September 2017Last modified: 18 April 2024

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    Bedding size guide


    These are standard UK bedding measurements so if you know your mattress size, you can easily work out which duvet size you need. (Width x length.)

    UK sizes Duvet size Mattress size
    Single 135 x 200cm (53 x 79") 90 x 190cm (36 x 75")
    Double 200 x 200cm (79 x 79") 135 x 190cm (53 x 75")
    King 225 x 220cm (89 x 87") 150 x 200cm (60 x 78")
    Super king 260 x 220cm (102 x 87") 180 x 200cm (72 x 78")

    US/CANADA BEDDING SIZES: Approximate matches to UK sizes are US King/UK Super king, US Queen/UK King,  US Full/UK Double and US Twin/UK Single.

    EUROPEAN BEDDING SIZES: Each size - Single, Double, King and Grand king - is a little larger than the UK equivalent.

    Measure your mattress to see which size bedding you need: our UK v European v US mattress comparison guide.



    Young children can overheat so if they are old enough to use a full size bed, we recommend using a single size 4.5 tog duvet.

     Tog rating Season / heat Feel
    2.5 tog High summer / hot sleepers Light thermal insulation
    4.5 tog Summer Lower thermal insulation
    9 tog Spring & Autumn Cosy medium heat
    All season 13.5 tog 4.5 tog + 9 tog Very warm
    All season 11.5 tog 2.5 tog + 9 tog Warm
    All season 7 tog 2.5 tog + 4.5 tog Lower warmth



    Our goose down duvets have high 700 fill power. Fill weight is measured in GSM (grams per square metre). For example view our 9 tog king size goose down duvet for more duvet details.

    Fill weight (not total duvet weight)
    Single All seasons - 788gsm
    9 tog - 486gsm 
    4.5 tog - 302gsm 
    2.5 tog - 220gsm
    Double All seasons - 1168gsm
    9 tog - 720gsm
    4.5 tog - 448gsm
    2.5 tog - 320gsm
    King All seasons - 1478gsm
    9 tog - 911gsm
    4.5 tog - 567gsm
    2.5 tog - 400gsm
    Super king All seasons - 1671gsm
    9 tog - 1030gsm
    4.5 tog - 641gsm
    2.5 tog - 480gsm



    Our pillows come in two sizes and two firmness options. (Width x length.)

    Standard  50 x 75cm
    King 50 x 90cm



    Our fitted sheets are deep fit, up to 40cm / 15.7" mattress depth. And our duvet covers fasten with large, easy to use buttons. (Width x length.)

    Duvet cover Fitted sheet Flat sheet Pillowcase (pair)
    Single 140 x 200cm 90 x 190cm 180 x 275cm
    Double 200 x 200cm 135 x 190cm 230 x 275cm 50 x 75cm (Standard)
    King 230 x 220cm 150 x 200cm 275 x 275cm 50 x 90cm (King)
    Super king 260 x 220cm 180 x 200cm 305 x 275cm



    Our mattress protectors are deep fit, up to 40cm mattress depth. Choose the same size protector as your mattress size. (Width x length.)

    Mattress protector size Mattress size
    Single 90 x 190cm 90 x 190cm
    Double 135 x 190cm 135 x 190cm
    King 150 x 200cm 150 x 200cm
    Super king 180 x 200cm 180 x 200cm 


    £10 off your first order over £200!

    Luxurious bedding & towels | scooms

    + First access to new products, clearance sales & special offers.