Here is a simple calculator for this:
https://docs.google.com/spreadsheet...zOEbB5pSJMOjeiR-ES4y0HOzxy8/edit?usp=drivesdk
(It's in read-only mode, you have to make your own copy to use it)
Here is how it looks like:
On the left, just specify how many of each engine you use. Ignore the "unused" column.
On the right, specify how many tons of fuel tank you have, and the dry mass of remaining parts.
This is the only tricky part, you must not include the engines and the fuel tanks in dry mass, they are already accounted for.
Then in the blue tables below, you have everything you want to know.
For example, if your ship is compound of a broadsword, a 20 tons fuel tank, a capsule and a parachute, you will enter:
- 1 broadsword in engine specs
- 20 tons for fuel tank
- 4.5 tons for dry mass (capsule + parachute = 4.5 tons)
As you see it's very simple, but it only works for a stage at once. If you have upper stages, you have to include them in dry mass.