Work backwards from a deadline to find the latest possible start date.
Backward scheduling reveals whether a deadline is already unachievable, because the required start date may be in the past. Including a buffer makes the schedule survivable rather than merely feasible. A start date that has already passed is the clearest possible signal that scope or deadline must move, and finding it early is far cheaper than discovering it late.
Project Start Date
Step backwards from the deadline, counting only working days until the duration is covered
Step backwards from the deadline, counting only working days until the duration is covered Backward scheduling reveals whether a deadline is already unachievable, because the required start date may be in the past. Including a buffer makes the schedule survivable rather than merely feasible.
A start date that has already passed is the clearest possible signal that scope or deadline must move, and finding it early is far cheaper than discovering it late.
This calculator takes 6 inputs: Deadline year, Deadline month, Deadline day, Duration in working days, Public holidays in the period, Buffer before the deadline. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.