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📐 PERT 三点估算计算器（工期与完工概率）PERT Calculator (Three-Point Estimate)
按 PERT 三点估算公式 E = (O + 4M + P) / 6、σ = (P − O) / 6，逐项计算任务的期望工期和标准差，汇总关键路径总工期，并估算在截止日期前完成的概率和 80%/90%/95% 把握的工期。Apply the PERT three-point formulas E = (O + 4M + P) / 6 and σ = (P − O) / 6 to each task, total the critical path, and estimate the chance of finishing by a deadline along with the 80%, 90% and 95% confidence durations.
使用说明与常见问题How-to & FAQ
「PERT 三点估算计算器（工期与完工概率）」是什么？What is the PERT Calculator (Three-Point Estimate) tool?
按 PERT 三点估算公式 E = (O + 4M + P) / 6、σ = (P − O) / 6，逐项计算任务的期望工期和标准差，汇总关键路径总工期，并估算在截止日期前完成的概率和 80%/90%/95% 把握的工期。Apply the PERT three-point formulas E = (O + 4M + P) / 6 and σ = (P − O) / 6 to each task, total the critical path, and estimate the chance of finishing by a deadline along with the 80%, 90% and 95% confidence durations.
如何使用「PERT 三点估算计算器（工期与完工概率）」？How do I use the PERT Calculator (Three-Point Estimate) tool?
在「PERT 三点估算计算器（工期与完工概率）」中，填写「单位」、「截止工期（可选）」等参数，结果会随输入实时计算并显示在下方。In the PERT Calculator (Three-Point Estimate): Fill in "Unit", "Deadline (optional)"; results are recalculated instantly as you type.
PERT 三点估算公式是什么？What are the PERT formulas?
每项任务给出乐观 O、最可能 M、悲观 P 三个工期，期望工期 E = (O + 4M + P) / 6，标准差 σ = (P − O) / 6（PERT 的 β 分布近似，见 PMBOK 指南）。串联任务的总工期是各 E 之和，总标准差是各 σ² 之和再开方（假设各任务互相独立）。Each task gets optimistic O, most likely M and pessimistic P durations: expected E = (O + 4M + P) / 6 and standard deviation σ = (P − O) / 6 (the PERT beta approximation, as in the PMBOK Guide). For tasks in sequence the total is the sum of the E values and the total σ is the square root of the summed σ² (assuming the tasks are independent).
任务应该填哪些？Which tasks should I enter?
填关键路径上依次进行的任务。并行的任务不应相加；如果有多条路径，请分别计算，取总工期最长的那条。Enter the tasks on the critical path, one after another. Parallel tasks should not be added together; with several paths, work each one out and use the longest.
完工概率可靠吗？How reliable is the completion probability?
它把总工期近似看成正态分布（中心极限定理），任务越多越接近；任务很少或估计偏差很大时只能作为粗略参考。80%/90%/95% 工期按 E + z·σ 计算，z 分别为 0.8416、1.2816、1.6449。It treats the total as roughly normal (central limit theorem), which works better with more tasks; with only a few tasks or very lopsided estimates treat it as a rough guide. The 80%, 90% and 95% durations are E + z·σ with z = 0.8416, 1.2816 and 1.6449.
默认的任务是什么？What are the default tasks?
默认的两行只是示例：Design 2 4 6 和 Build 3 5 13，总期望工期 10，截止工期 12 时完成概率约 86.74%。请换成你自己的估算。The two default lines are only an example — Design 2 4 6 and Build 3 5 13 — giving an expected 10 and about an 86.74% chance by a deadline of 12. Replace them with your own estimates.
「PERT 三点估算计算器（工期与完工概率）」免费吗？需要注册吗？Is the PERT Calculator (Three-Point Estimate) free? Do I need an account?
「PERT 三点估算计算器（工期与完工概率）」完全免费，无需注册或安装，打开网页即可使用，手机和电脑都能用；输入的内容只在你的浏览器本地处理。The PERT Calculator (Three-Point Estimate) is completely free with no sign-up or install and works on phones and desktops; what you enter is processed only in your browser.