Plank Time Percentile Calculator
See where your plank hold time ranks with an estimated percentile and core-endurance rating, based on typical adult plank norms.
How it works
percentile = Φ((time − mean) ÷ SD) × 100 · normal model, mean/SD from adult plank norms
A front plank measures isometric core endurance — how long the deep trunk muscles can resist gravity before form breaks. There is no single official norm table, so this tool models adult hold times as a normal distribution (men centred near 100 seconds, women near 80) and reports where you fall using the normal cumulative distribution. Treat the percentile as a well-reasoned estimate, not a certified standard: form quality matters as much as raw time, and a shaking, sagging plank does not count.
Worked example
A man holding 90 seconds against a mean of 100 and SD of 50: z = (90 − 100) ÷ 50 = −0.2, and Φ(−0.2) ≈ 0.42, so about the 42nd percentile — a “Good” hold just below the typical time.
Sources: Plank (exercise)
Frequently asked questions
What is a good plank time?
For most adults, 60 seconds is respectable, 2 minutes is strong, and beyond 3–4 minutes is elite core endurance. Past that, hold time becomes more a test of mental grit than a useful fitness marker — added core challenge beats simply holding longer.
How exact is the percentile?
It comes from a normal-distribution model of typical adult plank times, not a specific published table, so read it as a ballpark. Your real ranking depends on the population you compare against and, critically, on strict form.
Why cap the benefit of very long holds?
Once you can plank a few minutes, core endurance is well developed and longer static holds add little. Progress to harder variations — weighted planks, long-lever or single-limb holds — instead of chasing bigger clock numbers.
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This calculator is for educational purposes. Double-check important results before acting on them.