15ml of dye should color approx. 20 kgs of wax to a medium shade. Suggested usage varies for each color & shade, and will also vary depending upon your wax formula and any additives you use.

Suggested usage Rates:
A medium shade is about 0.05% which equals approximately 8 drops of dye per 500g of wax.
For a dark shade, you should use 0.1% dye, which equals approximately 15 drops of dye per 500g of wax.
For pale shades, you should use 0.01% or 0.005%, which equals approximately 1-3 drops of dye per 500g of wax.