Forecast

A Monte Carlo cycle forecaster. Give it ranges for what's left, how much you typically finish per cycle, and how much scope tends to grow. It runs 10,000 simulations in your browser and shows the distribution of completion dates.

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Distribution

How often each cycle count showed up across 10,000 simulations. Taller bars = more likely outcomes.

≤ P50 P50–P85 P85–P95 > P95

Percentiles

"P85 = 12 cycles" means in 85% of simulations, the work was done in 12 cycles or fewer. Higher P = more confident, but later.

How the forecast works

What it does

Each run is one plausible future for the project: how big the work turns out to be, and how fast you finish it. We do 10,000 of these runs, sort the cycle counts, and tell you what fraction of futures finished by each cycle count. That's the histogram. The percentiles are summary points on the same data.

How items become a forecast

  1. Sample the item count from a triangular distribution over (low, likely, high). The "likely" value is the peak — most samples cluster around it, but some land at the extremes.
  2. Multiply by a uniform scope-creep factor drawn between (low, high). 1.0× = the work is exactly what you counted; 1.5× = expect about half again as much.
  3. At the start of each run, draw 2 throughput samples uniformly from (low, high). That's the run's throughput pool.
  4. Each cycle, draw one throughput value from the pool and subtract from items remaining. Repeat until items hit zero. The cycle count is the result of that run.

What the percentiles mean

P85 = 12 cycles means: in 85% of those 10,000 runs, the project finished in 12 cycles or fewer. Lower P is faster but riskier; higher P is safer but later. Pick the number that matches how much you care about being on time.

What the confidence bands mean

The four cards group the percentiles into ranges:

  • Optimistic — P50 to P70. The early-but-plausible window.
  • Likely — P70 to P85. Where most healthy commitments sit.
  • Projected — P85 to P95. Stretch confidence; good for external promises.
  • Conservative — P95+. "Almost certainly done by here."

The histogram colors track these same bands so you can read the cards and the chart against each other.

Assumptions and limits

  • The throughput pool is only 2 samples per run, so the spread between your low and high matters a lot. A tight range gives a narrow distribution; a wide range fans out fast.
  • Scope creep is uniform between low and high. Real projects usually have fatter tails on the high end — this model won't capture that.
  • Throughput is assumed stationary. No seasonality, no team changes mid-project, no cycle-over-cycle improvement or decay.