Project Buffer Size Calculator

Project Buffer Size Calculator

Rather than padding every individual task with its own safety margin, Critical Chain Project Management pools that safety into a single project buffer - this calculator estimates that buffer size.

Aggressive Chain Duration = Sum(Task Duration x 0.5)
Project Buffer = (Full Chain - Aggressive Chain) x Buffer %

Example

Task estimates of 10, 20, 15, and 25 days, 50% buffer percentage:

Full Chain = 70 days, Aggressive Chain = 35 days → Project buffer: 17.5 days

Why Use Aggressive (50%-Confidence) Estimates

Critical Chain Method deliberately uses aggressive, 50%-confidence task duration estimates (rather than padded, "safe" ones) for the working schedule, then protects the overall deadline with a single pooled buffer at the end of the chain instead.

Why This Often Shortens Overall Schedules

Pooling safety margin into one project buffer, rather than distributing it across every individual task (where unused safety margin on early tasks is commonly wasted through procrastination or scope creep), frequently results in a shorter overall project schedule while still protecting the final deadline.