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Find the conventional PERT expected duration and variance from three supplied estimates. Provide Optimistic duration, Most likely duration, Pessimistic duration to compute results directly in your browser. Require optimistic <= most likely <= pessimistic and one time unit. Mean=(O+4M+P)/6, variance=((P-O)/6)^2; model estimates, not a completion probability or delivery guarantee. Inputs and results use floating-point numbers; output shows up to 12 significant digits. Rounding can occur. Common search workflows supported include "pert calculator", "pert estimate calculator".
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Enter the inputs, then select Calculate.
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How the PERT Calculator Works & Core Formula
The PERT Calculator evaluates Optimistic duration, Most likely duration, Pessimistic duration in client-side JavaScript using the deterministic rule below and updates the output panel immediately without uploading data to a server.
Find the conventional PERT expected duration and variance from three supplied estimates.
Require optimistic <= most likely <= pessimistic and one time unit. Mean=(O+4M+P)/6, variance=((P-O)/6)^2; model estimates, not a completion probability or delivery guarantee. Inputs and results use floating-point numbers; output shows up to 12 significant digits. Rounding can occur.
PERT Calculator Quick Reference & Input Guide
Review the input parameters, allowed value ranges, and worked reference cases for the PERT Calculator below before running your calculation.
| Parameter / Scenario | Default / Sample Value | Rule or Allowed Range | Output / Usage Note |
|---|---|---|---|
| Input: Optimistic duration | 1 | Range: 0 to 1000000000.0 | Required workspace parameter |
| Input: Most likely duration | 2 | Range: 0 to 1000000000.0 | Required workspace parameter |
| Input: Pessimistic duration | 3 | Range: 0 to 1000000000.0 | Required workspace parameter |
| Worked Case 1: Baseline run (Optimistic duration = 1) | Preloaded / test values | Find the conventional PERT expected duration and variance from three supplied estimates | Optimistic duration = 1; Most likely duration = 2; Pessimistic duration = 3. The displayed output is Expected duration: 2 Variance: 0.111111111111. |
| Worked Case 2: Comparison scenario (pert calculator compound interest) | Preloaded / test values | Find the conventional PERT expected duration and variance from three supplied estimates | Optimistic duration = 2; Most likely duration = 5; Pessimistic duration = 8. The displayed output is Expected duration: 5 Variance: 1. |
Step-by-Step Guide to Using the PERT Calculator
Follow these three steps to configure Optimistic duration, Most likely duration, Pessimistic duration, verify unit and boundary rules, and export your PERT Calculator output.
Input and settings
Complete the other inputs
Set most likely duration, pessimistic duration. Enter optimistic, most likely and pessimistic durations in that order and in one time unit.
Tool result
Calculate and read the output
Select Calculate to see the conventional PERT expected duration and variance. Copy result copies this text; Download saves it as a TXT file.
Review the details
Practical Worked Examples for PERT Calculator
These concrete scenarios illustrate how the PERT Calculator processes baseline inputs, comparison checks, and boundary constraints.
Baseline run (Optimistic duration = 1)
Optimistic duration = 1; Most likely duration = 2; Pessimistic duration = 3. The displayed output is Expected duration: 2 Variance: 0.111111111111.
Comparison scenario (pert calculator compound interest)
Optimistic duration = 2; Most likely duration = 5; Pessimistic duration = 8. The displayed output is Expected duration: 5 Variance: 1.
Boundary & unit check (Pert Calculator)
When solving for 'pert calculator', verify that Optimistic duration, Most likely duration, Pessimistic duration use consistent units and stay within the documented scope: Require optimistic <= most likely <= pessimistic and one time unit. Mean=(O+4M+P)/6, variance=((P-O)/6)^2; model estimates, not a completion probability or delivery guarantee. Inputs and results use floating-point numbers; output shows up to 12 significant digits. Rounding can occur.
How to Read and Verify the PERT Calculator Output
The output panel reports the exact result derived from Optimistic duration, Most likely duration, Pessimistic duration alongside any unit or formatting notes.
The result is the conventional PERT expected duration and variance. Combine three duration estimates with the stated PERT weighting.
The estimate uses the supplied values; it does not calculate a project's completion probability or a guaranteed delivery date.
Numerical output shows up to 12 significant digits. Floating-point arithmetic and display rounding can affect the last digits.
- Example input
- Optimistic duration = 1; Most likely duration = 2; Pessimistic duration = 3
- Example output
- Expected duration: 2 Variance: 0.111111111111
Scope Limits, Accuracy Assumptions & Related Everyday Math Tools
Review these boundary constraints and validation rules before relying on the PERT Calculator output.
Operational scope: Require optimistic <= most likely <= pessimistic and one time unit. Mean=(O+4M+P)/6, variance=((P-O)/6)^2; model estimates, not a completion probability or delivery guarantee. Inputs and results use floating-point numbers; output shows up to 12 significant digits. Rounding can occur. Inputs that violate minimum/maximum bounds or required format rules are rejected with a clear diagnostic prompt.
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Open toolFrequently Asked Questions About PERT Calculator
Answers about using PERT Calculator and understanding its results.
What formula or rule does the PERT Calculator use?
The PERT Calculator applies the rule: Find the conventional PERT expected duration and variance from three supplied estimates. Enter Optimistic duration, Most likely duration, Pessimistic duration into the workspace and the tool computes the exact output in your browser.
Can I use this tool for pert estimate calculator?
Yes. Provide Optimistic duration, Most likely duration, Pessimistic duration using the documented units and format shown in the quick reference table above. Preloaded default values let you test the workflow immediately.
What are the accuracy limits and boundary assumptions for PERT Calculator?
Require optimistic <= most likely <= pessimistic and one time unit. Mean=(O+4M+P)/6, variance=((P-O)/6)^2; model estimates, not a completion probability or delivery guarantee. Inputs and results use floating-point numbers; output shows up to 12 significant digits. Rounding can occur. Confirm that your inputs fall within the allowed ranges before exporting the result.
Is the PERT Calculator free and does it keep my inputs private?
Yes. All calculations for the PERT Calculator execute 100% locally in your browser's JavaScript runtime. No inputs or results are uploaded to any external server.
Get the conventional PERT expected duration and variance
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