Lemon Balm Yields, German Chamomile Seeding Rates

I am working on my seed order and I have a question. Do you have information about what the average yield should be from lemon balm? I am trying to figure out how much seed I need to by to produce 25lb of dried herb?

When lemon balm is spaced 50 to 75 by 15 to 30 centimeters in the field, an average yield would be 4000 kilogram of dried herb per hectare. This works out to 0.4 kilogram per square meter of field planted at the above densities. In other words you get almost a pound per square meter.
The seeding rate is 7.5 to 9 kilogram of seed per hectare. If you want to do indirect seeding, you will need 3 to 5 gram of seed to produce 1000 plants for transplanting into the field.

One more question, how big an area would a packet of german chamomile seed cover?

About a 10 meter long row.