There is no 'simple' training budget formula. Why? Because planned training for any organisation is heavily reliant upon a number of significantly variable factors. Some of these are:
* Training types required,
* Calibre of trainers required to deliver training,
* Complexity of training,
* Frequency of training,
* Mandatory or optional training,
* Specialist or non-specialist training,
* Technical or non-technical training,
* Regulatory training, etc...
As a rule of thumb, most large organisations (and by that I mean with turnovers in excess of at least 100 million USD) will earmark a minimum of 3 - 4% for training. To this, they then add 'special purpose training', project related training, delivery related up-skilling training, optional training requests from their people etc...
You've got to remember that a training budget is not a trivial exercise. It is a very specialised and involved process that requires significant input from all departments and sections of any organisation. Admitted that the final responsibility of preparing it rests with the training manager or equivalent. But, almost all inputs will come from the organisation's people.
I hope this helps in guiding your thoughts.
And, in case you are open to external consultants preparing your training budget, feel free to ring me on the details below.
Take care!