Is my maths equation correct for breaking down grams to find correct klj?

petrinaradford
petrinaradford Posts: 77 Member
in Food and Nutrition
Ok so I have a jar of leggos pesto. On the jar it reads 47g portion size to be 465klj.
So I don’t want to use 47g, I want a lot less, say two teaspoons so 10g

This is what I came up with, not sure if I’m on the right path:

47g = 465klj
47g/ 2 = 23.5g

465klj /2 = 232.5klj
So therefore 23.5g of pesto = 232.5klj

Can I just keep dividing, like this?

Replies

  • petrinaradford
    petrinaradford Posts: 77 Member
    It doesn’t seem to match up with calorieking ...
  • J_NY_Z
    J_NY_Z Posts: 2,535 Member
    I came here for math.

    @just_Tomek maths are correct for 10 grams.

    A further analysis will show that 1 gram of your pesto sauce will be ~10kJ. From there you can pick whatever portion you want in grams and multiply that by 10.
  • BarbaraHelen2013
    BarbaraHelen2013 Posts: 1,940 Member
    edited September 2019
    Why not let MFP do the maths for you?

    Set the energy unit you use to KJ and search your food item. Change the serving size on that entry to 1g and set the serving size to 10. It comes out as 99KJ.

    I use calories but just switched to kilojoules to see it that change carries through to the database. It works perfectly.

    It also gave me scary high number at the top of my diary, so I’ve changed it back! 😂
  • petrinaradford
    petrinaradford Posts: 77 Member
    Hahaha oh thanks everyone 😊👍
  • MPDean
    MPDean Posts: 99 Member
    What works for me

    Energy per serving divided by serving size in grams gives energy per gram.

    Number of grams multiplied by energy per gram gives the amount of energy eaten.

    465 kJ ÷ 47 g = 9.9 kJ/g

    9.9 kJ/g × 10 g = 99 kJ
  • petrinaradford
    petrinaradford Posts: 77 Member
    MPDean wrote: »
    What works for me

    Energy per serving divided by serving size in grams gives energy per gram.

    Number of grams multiplied by energy per gram gives the amount of energy eaten.

    465 kJ ÷ 47 g = 9.9 kJ/g

    9.9 kJ/g × 10 g = 99 kJ


    Thanks this is clear as, exactly what I was looking for. Now I know how to work it out. Thank you 😃✌️

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