Syn calculation

Last updated on Fri, 21st Oct 2022

On top of all the free foods you can eat on Slimming World you’re allowed between 5 and 15 syns per day (and men get more!) to use on whatever you like – be that non-free ingredients in recipes, or treats such as chocolate.

Your Slimming World book lists the syn values for lots of different foods. However it’s not exhaustive, so the Slimming World website has an official Syns Online database of foods, where they have pre-calculated the syn values of loads of different brands.

If you can’t find a suitable listing in the database, then they also have a syns calculator where you can enter the nutritional information from the food label (calories, protein, fat, and carbs) and specify your portion size, and it’ll tell you the syn value.

Nutrition information for a packet of cooked rice

Slimming World also offer a service whereby you can send them photos of food packaging from the UK or Ireland, and they will calculate the syn value and add it to their Syns Online database – normally within a day or two.

Approximate calculation

If you don’t have the time or means to look up the exact syn values in your book or online, and you want an idea of the approximate number of syns in something, then the general rule of thumb is that 20 calories = 1 syn.

So, for example, my favourite can of Hufi beer is 140 calories – so that would equate to 7 syns.

This approximate calculation pretty good for non-free foods that don’t have much nutritional benefit (such as chocolate or alcohol). If you’re eating foods that have an amount of fibre or protein, for example, then the syn values will vary from this formula.


  1. Lorna while said:

    Hi there, help! I’m new to SW and cant join due to lockdown but hate diet apps as they are quite simply painful. I plan on joining as soon as lockdown lifts at a class near by. In the meantime I need to know what these SW equations mean? For example. 1.5+HEA (3)?????? Not a clue. Thankyou in advance. Lorna

    Wed, 4th Nov 2020
    • Becca said:

      The note that you’ve copied there is for a recipe I assume. It tells you that the recipe per portion is 1.5 syns and takes up one Healthy Extra A slot. If you don’t want to use the Healthy Extra A slot for the recipe then it is an extra 3 syns thus 4.5 syns per portion.

      Sun, 3rd Jan 2021

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