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S-Curve Generator

Compare cumulative planned and actual project progress or cost over time.

Free · No signup · Works in your browser

S-curve workspace

Enter non-cumulative values for each period. CalcsBay calculates cumulative planned and actual curves automatically.

Planned total

100%

Actual to date

60%

Planned to date

70%

Variance

-10%

Cumulative planned vs actual
PlannedActual
0%25%50%75%100%Week 1Week 2Week 3Week 4Week 5Week 6Week 7Week 8Week 1: planned 5%Week 2: planned 15%Week 3: planned 30%Week 4: planned 50%Week 5: planned 70%Week 6: planned 85%Week 7: planned 95%Week 8: planned 100%Week 1: actual 4%Week 2: actual 12%Week 3: actual 25%Week 4: actual 43%Week 5: actual 60%
#PeriodPlannedActualCum. plannedCum. actualDelete
15%4%
215%12%
330%25%
450%43%
570%60%
685%60%
795%60%
8100%60%
Changes are saved automatically in this browser.No signup · No server upload

Values are calculated and charted locally in your browser.

What is an S-curve and why is it used?

An S-curve plots cumulative project value over time, commonly using cost, labor hours, quantities or weighted progress. The curve often starts slowly, rises during peak delivery and flattens near completion, making planned-versus-actual performance easy to compare.

How to use the S-Curve Generator

  1. Step 1Choose whether the values represent progress, cost, hours or another consistent measure.
  2. Step 2Enter planned and actual non-cumulative values for each reporting period.
  3. Step 3Compare the cumulative curves to identify variance, delayed progress or changing delivery trends.

Formula / How it works

Cumulative value for each period equals the sum of all period values up to that point.

Example

Enter weekly planned and actual values to compare cumulative performance on an S-curve.

S-Curve Generator FAQ

Why is it called an S-curve?

Many projects mobilize gradually, accelerate through the main delivery phase and slow during completion, producing a cumulative line that resembles an elongated letter S.

What does it mean when the actual curve is below the planned curve?

For progress or earned-value data, it usually indicates that cumulative delivery is behind plan. For expenditure alone, it can also reflect delayed spending or cost savings, so the data type must be considered.

Should I enter cumulative or period values?

Enter the value achieved within each individual period. The tool calculates the cumulative planned and actual totals automatically.

Can an S-curve predict the final project outcome?

It reveals trends and variance but does not by itself produce a reliable forecast. Combine it with schedule logic, remaining work, productivity and risk analysis.

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