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Scenario Analysis Calculator

Work out scenario analysis instantly with clear inputs, formula shown and shareable results.

About Scenario Analysis Calculator

Scenario analysis assigns probabilities to coherent states of the world rather than shocking one variable at a time. Weighting the base case heavily and splitting the remainder between best and worst gives an expected outcome and, more usefully, a dispersion measure for comparing projects of different sizes.

Formulas

Expected outcome

EV = Best x w + Base x Base weight + Worst x w, where w = (1 - Base weight) / 2

Coefficient of variation

CV % = Standard deviation / |Expected outcome| x 100

Worked example

With the default values below, Scenario Analysis Calculator returns Probability-weighted expected outcome of $1,360,000.00. Change any input above and every figure here is recalculated in your browser.

Inputs used

Best case outcome
2,400,000
Base case outcome
1,400,000
Worst case outcome
200,000
Weight on the base case
60

Results

Probability-weighted expected outcome
$1,360,000.00
Standard deviation of outcomes
$697,423.83
Best-to-worst spread
$2,200,000.00
Coefficient of variation
51.28%

Step by step

  1. 1Values used
  2. 2Expected outcome
  3. 3Coefficient of variation
  4. 4Probability-weighted expected outcome= 1,360,000.00
  5. 5Standard deviation of outcomes= 697,423.83
  6. 6Best-to-worst spread= 2,200,000.00
  7. 7Coefficient of variation= 51.28

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
  • This is an estimate for general information and not professional financial, tax or legal advice. See the full disclaimer for the limits that apply to this kind of calculator.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Why use the coefficient of variation?

Because standard deviation scales with project size. CV normalises it so a small risky project can be compared with a large stable one.

Should best and worst be equally likely?

Not necessarily, but splitting the residual weight evenly is a defensible default. Skew it if the downside is genuinely more likely.

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