An allowance you cannot see is an allowance you cannot check
Many cost estimates fold a vague "buffer for failures" into a single padded number without ever showing what that buffer actually is. That makes it impossible to tell later whether the buffer was too generous, too thin, or about right. This planner makes the failure allowance a visible, separate line, computed from a real or exploratory failure rate, so you can check it against what actually happens over time.
How the allowance works
If you supply your own historical failure rate (from tracking pass/fail on your own prints), it is applied directly to compute a cost and time allowance for this specific job. Without one, the tool uses a 10% exploratory default, explicitly labeled as an assumption rather than your measured rate, and recommends you start tracking your actual rate so future estimates can use real data instead.
Worked example
A $15, 6-hour job with an 8% historical failure rate: the allowance comes out to $1.20 in cost and about 0.48 hours in time, added visibly to the job's base cost and time rather than folded silently into one padded number.
A common mistake
A frequent error is setting a failure allowance once and never revisiting it as your process matures. A rate that made sense when you were new to a material or geometry type is often too high once you have printed it successfully many times, quietly overcharging every job for a risk that no longer reflects reality. Recheck this periodically against your actual recent experience.
Limitations
This converts a stated or exploratory failure rate into a visible cost and time allowance; it does not know your true failure rate unless you measure and supply it. An unmeasured allowance carries real uncertainty, labeled explicitly here rather than hidden inside a single blended number.