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S Curve in Project Management

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In project management, the “S curve” is a graphical representation of the cumulative costs, progress, or performance of a project over time. It is called an S-curve because the plotted points form a shape resembling the letter “S” when connected.

The S-curve typically shows the planned progress or performance against the actual progress or performance of a project. It is commonly used to track and visualize the project’s status, compare planned versus actual progress, and predict future performance.

The horizontal axis of the S-curve represents time, while the vertical axis represents the project’s progress, cost, or performance. The curve starts slowly at the beginning of the project, indicating a gradual increase or slower progress. As the project progresses, the curve steepens, indicating faster progress. Eventually, it levels off as the project nears completion.

Key Characteristics of and S Curve

Here are the key characteristics of an S-curve:

Slow start: At the beginning of the project, the curve starts with a shallow slope, indicating slower progress or performance.

Rapid growth: As the project moves forward, the curve becomes steeper, reflecting accelerated progress or performance.

Peak performance: The curve reaches its maximum slope, indicating the period of highest progress or performance during the project.

Slowdown: After reaching the peak, the curve starts to flatten out, indicating a gradual decrease in the rate of progress or performance.

The S-curve is a useful tool for project managers to monitor the project’s performance, identify any deviations from the planned schedule or budget, and make necessary adjustments. By comparing the planned and actual curves, project managers can determine if the project is on track, ahead of schedule, or falling behind. It helps in analyzing project risks, resource allocation, and forecasting project completion.

Additionally, the S-curve can be used to estimate the total project cost by comparing the planned and actual costs at different stages of the project.

Overall, the S-curve provides a visual representation of a project’s progress or performance over time, helping project managers make informed decisions and effectively manage project execution.

How the S Curve is Plotted?

To plot an S-curve, you typically need data on the project’s progress, cost, or performance at different time intervals. Here’s a step-by-step guide on how to plot an S-curve:

Step by Step Procedure to Plot the S Curve

Gather data

Collect data on the project’s progress, cost, or performance at regular intervals. This could include the actual completion percentage, cumulative cost, or other relevant metrics. Ensure you have data points that span the entire project duration.

Create a time axis

Determine the time intervals for the project and set up a horizontal axis representing the project’s duration. You can use weeks, months, quarters, or any other suitable time units depending on the project’s duration.

Define the vertical axis

Decide what the vertical axis will represent. It could be the cumulative progress percentage, cumulative cost, or any other relevant measure. Make sure the scale on the vertical axis is appropriate to accommodate the data values.

Plot the planned curve

Start plotting the planned S-curve based on the project plan. Determine the expected progress or cost at each time interval and plot the corresponding points on the graph. Connect the points to form a curve that reflects the planned progression.

Plot the actual curve

Using the collected data, plot the actual progress or cost values at each time interval. Connect these points to form a curve that reflects the actual progression of the project.

Compare the curves

Compare the planned curve with the actual curve on the same graph. Analyze the differences and variations between the two curves. You can identify areas where the project is ahead of schedule, falling behind, or experiencing unexpected changes.

Interpret the S-curve

Analyze the shape of the S-curve. Observe the slow start, rapid growth, peak performance, and slowdown phases. Assess the project’s current status and estimate its future performance based on the curve’s shape.

Add additional information

You can enhance the S-curve by adding additional information, such as the baseline curve (the original planned curve), a target curve (desired performance or progress), or any other relevant reference lines.

Remember that the specific steps and details may vary depending on the context and purpose of the S-curve. Project management software or tools may also provide built-in features for generating S-curves based on input data.

How the S Curve is Plotted Using Microsoft Excel?

The step by step procedure of drawing S curve with the help of spreadsheet is shown below:

To plot an S-curve using MS Excel, you can follow these steps:

Step 1: Open MS Excel and create a new worksheet.

Step 2: Enter the time intervals or dates in one column under the heading “Time” (e.g., A2:A10).

Step 3: Enter the planned progress or performance values in another column under the heading “Planned” (e.g., B2:B10).

Step 4: Enter the actual progress or performance values in another column under the heading “Actual” (e.g., C2:C10).

Step 5: Select the data range that includes the time intervals, planned values, and actual values (e.g., A1:C10).

Step 6: Click on the “Insert” tab in the Excel ribbon. Choose the type of chart you want to create. For an S-curve, a line chart is typically used. Select the line chart type that best suits your needs (e.g., basic line chart or smoothed line chart).

Step 7: You should now have a line chart with the planned and actual curves representing the S-curve.

Step 8: Customize the chart as desired by adding axis labels, a chart title, legend, or any other formatting options.

Analyze the S-curve to assess the project’s progress, compare planned versus actual performance, and make informed decisions based on the insights derived from the chart.

From the above S curves of planned and progress data, we can see that initially the actual progress was slower than the planned one but after some time the actual progress increased and finally the planned progress was achieved by the project.

Excel provides various chart customization options, so feel free to explore the different features and settings to enhance the appearance and readability of your S-curve chart.

How to Interpret the S Curve in Project Management?

Interpreting the S-curve in project management involves analyzing the shape, position, and trends of the curve to gain insights into the project’s progress and performance. Here are some key aspects to consider when interpreting an S-curve:

Planned vs. Actual Progress

Compare the planned curve (baseline) with the actual curve. Assess whether the actual progress aligns with the planned progression. Identify areas where there are significant differences or deviations between the two curves.

Early Stages

Look at the initial portion of the S-curve. If the curve starts slowly with a shallow slope, it may indicate a slower start or initial challenges. It can also reflect the time required for project initiation, planning, and mobilization.

Steep Growth Phase

Examine the steep portion of the curve. This represents a period of rapid progress or performance improvement. It is an indicator of increased productivity and momentum in project execution.

Peak Performance

Identify the point of maximum slope in the S-curve. This represents the period of highest progress or performance. It indicates that the project is operating at its most efficient and productive stage.

Slowdown Phase

Observe the flattening of the curve after reaching the peak. This indicates a decrease in the rate of progress or performance improvement. It may be a sign of diminishing returns, resource limitations, or nearing completion of the project.

Comparison to Baseline and Target

Compare the actual curve with the baseline curve (initial plan) and target curve (desired performance or progress). Assess the gaps between these curves to determine if the project is ahead of schedule, on track, or falling behind.

Variations and Trends

Analyze the variations in the curve over time. Look for trends, patterns, or irregularities that could indicate changes in project performance. Identify any sudden drops, spikes, or plateaus that may require investigation and corrective actions.


Use the S-curve to forecast the future performance or completion of the project. Extrapolate the curve to estimate when the project is likely to reach specific milestones or objectives. This can assist in resource planning, scheduling, and decision-making.

Risk Identification

The S-curve can help identify potential risks and challenges. If the actual curve consistently lags behind the planned curve, it may indicate issues such as delays, cost overruns, or resource constraints. Early identification of such risks allows for timely mitigation.


Based on the interpretation of the S-curve, project managers can make informed decisions. They can allocate resources, adjust schedules, revise plans, or implement corrective measures to keep the project on track and improve overall performance.

Remember, the interpretation of an S-curve should be done in conjunction with other project management tools and techniques. It provides a visual representation of the project’s progress and performance trends, helping project managers monitor, evaluate, and control project execution effectively.


The S-curve in project management is a graphical representation of the cumulative progress, cost, or performance of a project over time. It provides project managers with a visual tool to track, compare, and analyze the planned versus actual progress of a project. By interpreting the S-curve, project managers can gain valuable insights into the project’s performance, identify deviations from the planned schedule or budget, forecast future progress, and make informed decisions to keep the project on track. The S-curve helps identify early challenges, assess peak performance, monitor slowdown phases, and recognize potential risks. It is an essential tool for effective project monitoring, control, and decision-making throughout the project lifecycle.

Also read: Scope Creep in Project Management, Reasons and How to Manage the Project Scope?

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Rajesh Pant
Rajesh Pant
My name is Rajesh Pant. I am M. Tech. (Civil Engineering) and M. B. A. (Infrastructure Management). I have gained knowledge of contract management, procurement & project management while I handled various infrastructure projects as Executive Engineer/ Procurement & Contract Management Expert in Govt. Sector. I also have exposure of handling projects financed by multi-lateral organizations like the World Bank Projects. During my MBA studies I developed interest in management concepts.
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