Soap making: How many bars of soap from 10 lbs of Base?

That will depend greatly on 2 main factors:
1) What size will the bars be?
And
2) What inclusions will you be adding?

Using a 10 lb batch of Melt & Pour Soap Base let's look as the general possibilities.
First you must factor in waste. If you are careful, there will be very little waste. There will be a bit wasted when skimming off surface foam. And a tiny bit lost to the sides of your melting pot. But you can save the foam for your own use and the "pot keep" can be left to become part of the next batch. Melt and Pour bases should be heated no hotter than 140 degrees F. Otherwise they boil, burn, cloud and discolor. 

Melt & Pour Base will harden quickly and will cling to your tools and there will be some unavoidable waste in the process. But again, this is easily removed for and placed in a small gauze bag for your own person use. Even the small amount of waste is still wonderful soap to use and enjoy.

(In our bulk soap orders we always include extra soap so, you can expect to get the full 160 - 1 oz bars from a batch of our melt and pour.)

With that in mind, the information below is a general guide:
Bath Bar size when calculating melt/pour base only (no herbs, oils, water, or scents added for these base calculations:
1 oz. Bars with no inclusions will yield approximately 157 to 160 bars.
1.5 oz. Bars with no inclusions will yield approximately 105 to 107 bars.
2 oz Bars with no inclusions will yield approximately 78 to 80 bars.
Smaller guest bars, depend on how small. Some are a very small fraction of an ounce but you will get several 100 of any size from 1/2 oz. and smaller.

When adding inclusions such as Lavender Buds, Oatmeal and powdered Loofa you can expect anything from a few more bars per 10 pounds up to double in the case in some of the herb bars that have equal amount of base and inclusion. Color and scent will add very little to the yield. Other things like adding Goat's milk, lotion base and a small amount of water or oils will have various increased amounts from almost unnoticed to a substantial number of additional bars.

But the bottom line is that 10 pound of base will produce a very reasonably priced bar of soap and when you consider the possibilities for creating your own real soap with so many wonderful personal touches, it is well worth considering. Be sure to keep some for your own use too.
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Enjoy the Ahhhhhs!