How to Find a Binomial Threshold with BINOM.INV in Excel

Use BINOM.INV to set alarm limits and guarantees: the smallest count that covers a chosen share of outcomes.

You will learn to

• Find an upper alarm limit for defect counts
• Find a lower "too good to be true" limit
• Turn a defect limit into a guaranteed number of good parts

How it works

BINOM.INV returns the smallest number of successes k for which the cumulative binomial probability reaches a target. With 200 inspected parts and a 3% defect rate, =BINOM.INV(200,3%,95%) returns 10: in 95% of normal batches you will see 10 defects or fewer.

That makes it the natural tool for setting alarm limits on counts — defects, complaints, returns — without trial and error. Pair it with the batch size to turn a defect limit into a promise about good units.

=BINOM.INV(200,0.03,0.95)