Weight of Beer or How to split a batch

[KRamey]

I am planning on doing one BIAB mash, and splitting the beer for two boils with two different hops. My plan is to split based on weight. One pot has a 1.4 gallon per hour boil off, and the other is just 1 gallon per hour, so they won't have the same volume of wort going into the boil.

My plan is to split by weight. My question is does wort weigh more than water, and if so by how much?

E.X. if going into the boil the gravity was 1.040 would that weigh 4% more than water. Assuming water weighs 8.33 pounds per gallon then wort would weigh 8.66 pounds per gallon.

OR is there an easier way to do this that I'm overlooking?

 

[GDRMaille]

If you have a digital scale, you could calibrate it with the empty kettles first. Once you took off each kettle, you could record the weight difference that you would subtract after you weighed the kettle with the boiled off wort. (don't forget to reset the scale each time!)