Probit Function Calculator
Free online probit function calculator. Enter your values and get instant results with the formula, step-by-step working, a worked example and FAQs — everything runs locally in your browser on Calcton, no signup required.
probit(p) = Φ⁻¹(p) = √2·erfinv(2p−1)，把概率扳回 z 分数刻度：probit(0.5) = 0，probit(0.975) = 1.95996，正好是 95% 置信区间的 z 值。Probit 回归、正态分位图（QQ 图）、安全系数的概率校准都以它为底座。
与 logit 的对比：中段两者几乎平行，尾部 probit 收敛到 ±∞ 的速度是多项式级（由 erfinv 的 1/√(−ln) 行为决定），比 logit 的指数尾更「胖」，这正是 probit 模型尾部分类更保守的原因。
参考值
probit(0.5) = 0，probit(0.975) = 1.959963984540054，probit(0.99) = 2.326347874040841
probit(0.999) = 3.090232306167813，probit(0.8413447461) ≈ 1
How to use the Probit Function Calculator
- Fill in the inputs with your own numbers — every field shows what it expects.
- The result updates instantly as you type; no "Calculate" click needed.
- Read the result card for the main figure, the step-by-step formula, and practical notes.
Frequently asked questions
Is the Probit Function Calculator free?
Yes — all math calculators on Calcton are free, with no sign-up required. Your inputs are processed in your browser and never sent to a server.
Is there a Chinese version of this tool?
Yes. Use the Chinese version link above — it is the same calculator with the interface in Simplified Chinese.
References
Formulas and benchmarks used by this calculator follow these published sources.
KevinContent LeadCalcton Editorial Team · Last updated 2026-09-27
Kevin maintains Calcton's formula verification and content: every calculator cites the standard it implements, worked examples are recomputed programmatically, and health benchmarks follow WHO and international guidelines.
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