SoapCalc is a great resource for making soap but it takes some work to navigate, especially the first few times you use it.
The main calculator used for soap recipes is located here — http://soapcalc.net/calc/SoapCalcWP.asp.
Moving in order through the numbered sections, for #1 you’ll typically select NaOH, which is the default choice. NaOH = Sodium hydroxide = lye.
For weight of oils i #2, I recommend that you change pounds to ounces. Keep in mind that this is weight of oils only, and not the total weight of your oils + water + lye + fragrance oils.
If you’re working with a 5 lb soap mold, that means your total weight of oils + water + lye + fragrance oils will equal about 80 ounces (5 lbs). The weight of just oils, however, is typically around 55 ounces to 60 ounces and that’s what you want to enter in #2.
This is tricky if you’re using an odd-sized mold and it will be different if using a 1 lb mold versus a 2 lb mold, etc. It’s also annoyingly hard as with a brand new recipe you won’t know the amount of water and lye until you run the recipe through SoapCalc.
The best thing I can suggest is to guesstimate at first, create your recipe, then see how much lye + water + fragrance it suggests to add. Total that up with the suggested oil weights and see how close it is to your mold volume, then adjust up or down as needed.
Err on the side of too much, as you can still fill your mold and adjust the recipe for the next batch.
Leave #3 and #4 as is when first starting with the default choices. With experience, you may decrease the water as % of oils and add more oils as superfat, but when beginning the default choices are fine.
In section #5, you’ll see many items listed under “Oils, Fats, and Waxes”. If you click on one, you’ll see the properties of that oil to the left under “Hardness”, “Cleansing”, etc.
Select an oil you’d like to add to your recipe, then click the “add” button under section #6. You’ll see your oil name appear in section 6 now.
Add each oil that you’d like in your recipe. Order doesn’t matter. If you need to remove one, enter the number of the line its on next to the “Remove #: button, then click the button.
Once you’ve added your oils that you’d like to use, you need to add percentages for each. This takes some playing around and experimentation, but a good starting point for beginners would be 50% olive oil, 20% coconut oil, 10% castor oil, and then the remaining 20% of oils whatever you’d like to try or have on hand.
Once you have your oil percentages entered, click “Calculate Recipe” in section #7. Some numbers will pop up on the screen.
Now click “View or Print Recipe” and your soap recipe will pop up in a new window.
Under the colored section for “Water”, “Lye”, “Oils” and “Fragrances” you’ll see listed the suggested amounts to add of each oil, shown in pounds, ounces, and grams. Ounces are typically the easiest to work with so I’d suggest using those.
At the bottom under “Soap Bar Quality”, you’ll see how your recipe measures up to the recommended ranges. Don’t worry if you’re not within the ranges as these are guidelines and not hard rules.
If you want to tweak your recipe, go back to the first window and simply make changes, then click “”Calculate Recipe” and then “View or Print Recipe”. That will now display the new tweaked recipe.
At the bottom is a print page function and you can also copy/paste it out into a Word doc or Excel.
While it’s a lot of steps, it gets easier with practice and most steps are straightforward. The trickiest part is knowing the weight of oils to enter in #2 when starting with a brand new recipe (and not adjusting an existing one) but a little trial-and-error will get you there.