Question for florists: How can I calculate the number of flowers for a bouquet?

I saw on www.aquarelle.co.uk that for a bouquet having a diameter of 30 cms one needs 32 roses, for one of 25 cms: 27 roses and for one of 35 cms in diameter 37 roses. I want to use different varieties of flowers instead of roses, but do not know if this proportions will do. How does a professional florist determine the number of flowers vrs. volume proportion when making a bouquet?

Question for florists: How can I calculate the number of flowers for a bouquet?
its a judge ment by eye . i have been a florist for over 11 years and specialize in weddings. everything is eye judge ment and perception. are the flowers the same size as the roses? are they smaller? judge taht way , plus a 32 rose bouquet is a large bouquet, that would be be for a large size or taller girl
Reply:Usually by how much the customer wants to spend the rest is made up of green filler and gyp...... I suspect that you will need fewer flowers than what you read for the roses.....all depends how perfectly symetrical and how big you want it to be.
Reply:Asking a florist how many flowers you need is a little like asking a barber if you need a haircut.