How to measure 7g yeast and 10g salt without a proper scale?

(1) A packet of yeast is typically 7g exactly. So if you're buying yeast by the packet, use one packet. But assuming you will be measuring from bulk yeast, the correct measure by volume would be 2 1/4 tsp instead of 2 1/2 tsp.

(2) The weight of salt relative to its volume varies considerably depending on what salt you are using - the best way to work out the appropriate conversion for the salt you have on hand is to consult the Nutrition Facts on the back of the container. Most salt gives the nutritional information based on 1/4 tsp. - but the weight of this amount of salt depends on the type of salt and size of grain.

Here's how you do the math.

Start with the information on the back of your package - for example, let's use my Fine Mediterranean Sea Salt - 1/4 tsp. = 1.2 g.

Multiply both sides by 4 to get the weight of 1 tsp. - 1 tsp. = 4.8 g - i.e. 4.8 g. per tsp.

You need 10 g - so divide 10 g by 4.8 to get the number of tsp. you should use - 10 / 4.8 = a little more than 2 tsp.

You really should get your measurement this way instead of relying on a generic conversion formula. There is significant variability from salt-to-salt. Another salt I use has a label that states 1/4 tsp. = .7 g (the crystals are larger so the same 1/4 tsp. now weighs much less than the sea salt).

1/4 tsp. = .7 g. (multiply both sides by 4)

1 tsp. = 2.8 g.

So this salt is 2.8 g. per tsp.

You need 10 g - 10 / 2.8 = a little more than 3.5 tsp.