Excel Chart Overlay: How to Plot Two Data Sets Together

Yes. In Excel for Microsoft 365 on Windows, you can overlay two data sets by adding both as series in one chart: select the chart, choose Chart Design > Select Data > Add, and specify the second series. To compare series with different scales or purposes, use a combo chart or put one series on a secondary axis.

What an Excel chart overlay means

An overlay usually means displaying two or more data series within the same chart area, rather than placing separate charts beside each other. For example, one chart might show monthly revenue and monthly expenses as two lines, or show actual sales alongside a target. The series share a chart and can be compared at a glance.

There are a few different things people mean by “overlay,” and the distinction matters. Adding two lines to one chart is a straightforward comparison. Combining a line and a column chart is a combo chart. Making two column series occupy the same category position is a series-overlap setting. These approaches look different and answer different questions.

Before building the chart, arrange the data so that each row represents the same category or time period, and each data set has a clear heading. A simple table might have Month in column A, Revenue in column B, and Expenses in column C. Matching months give Excel a sensible basis for comparing the series. If the data sets use different dates, units, or category labels, resolve those differences before treating them as directly comparable.

Add two data sets to one chart

If both data sets are in neighboring columns with a shared category column, the easiest method is to select the whole table and insert a chart. Excel will usually use the first column for category labels and each remaining column as a series. For example, selecting Month, Revenue, and Expenses together can create a chart with both measures.

Put a heading above each data series and place the category labels in the first column.
Select the complete data range, including the headings and category labels.
Choose Insert, then select a suitable chart from the Charts group. A line chart works well for trends over time; clustered columns work for comparing values across a limited number of categories.
Check that both series appear in the chart and that the horizontal axis shows the expected categories.
If the chart is missing a series or labels, select it and choose Chart Design > Select Data to correct the source ranges.

The Chart Design tab appears when a chart is selected. To add a series after creating the chart, choose Chart Design > Select Data, then select Add in the Legend Entries (Series) area. In the Edit Series dialog, set the series name to a heading cell or type a name, and set Series values to the cells containing the values. Do not include the heading cell in the values range. Confirm the dialog, then check the chart and its legend.

For a chart using category labels, the Select Data Source dialog also lets you edit the Horizontal (Category) Axis Labels. Choose Edit there and select the category cells, such as the month names. If the chart uses an XY scatter type, Excel instead expects numeric X values and Y values for each series; those are specified in the series editing dialog. A scatter plot is appropriate when the horizontal values are measurements, dates represented as numbers, or other numeric positions rather than just labels.

Use data in separate or nonadjacent ranges

The data sets do not have to sit next to each other. Create a chart from the first range, then use Chart Design > Select Data > Add to point the new series to the second range. This is often clearer than selecting nonadjacent cells before inserting the chart, especially when the ranges are on different parts of a worksheet. You can select the series name from a heading cell and the values from the matching data cells.

Make sure the category labels correspond in order. If one series has January through December while the other starts in February, Excel may still plot both, but the values can be paired with the wrong labels or appear offset. Add or align the missing categories so that every row represents the same month, product, region, or other category. For time series, check whether dates are actual Excel dates rather than text that only looks like a date.

For an XY scatter chart, add each series with its own X and Y ranges. The two series can have different X values, which is useful when measurements were taken at different intervals. In contrast, a line chart normally uses a shared set of category positions. If a scatter chart shows an unexpected horizontal scale, inspect the X values and confirm they are numeric.

Choose a chart type that fits the comparison

Two data sets do not automatically need two different chart types. Use the same chart type when the series represent comparable measures and share a meaningful scale. Two line series are a natural choice for trends, while two clustered column series can compare amounts for categories such as products or quarters. A scatter chart helps show the relationship between two numeric variables, such as advertising spend and sales, when each observation has an X and a Y value.

Use a combo chart when the series have different roles or when one chart type communicates a particular measure better. A common example is monthly sales as columns with a moving measure or target as a line. Select the chart, choose Chart Design > Change Chart Type, and select Combo. In the combo chart options, choose a chart type for each series. Depending on the selected types and the chart, you can also select Secondary Axis for one series.

Combo charts are not a universal way to combine every chart type. Excel offers compatible combinations, and some chart types have different data requirements. If the Combo option does not offer the type you need, use a supported pairing, or make separate charts. A second chart can be more honest and easier to read than a forced overlay.

When to use a secondary axis

A secondary vertical axis can help when two series are measured in substantially different units or ranges. For instance, a chart might show monthly orders in the hundreds and a conversion rate as a percentage. Plotting both against one scale can flatten the smaller-range series near zero. In a combo chart, assign one series to the secondary axis using the Secondary Axis option. You can also select a series, open Format Data Series, and choose Series Options > Secondary Axis.

Label both axes clearly, including their units. If one axis shows dollars and the other shows a percentage, say so in the axis titles or nearby labels. A secondary axis does not convert or normalize the data; it gives the second series a separate scale. This can make two trends look more similar or more different depending on the scale limits, so readers may draw the wrong conclusion if the axes are unlabeled or poorly chosen.

Use a secondary axis only when it improves interpretation. If the measures are comparable, a shared axis is usually easier to understand. If the goal is to compare the direction of change rather than the actual values, explain the scaling clearly or consider indexing both series to a common starting point in the source data. Do not assume that overlapping lines mean the underlying quantities are equal when they use different axes.

Make column series overlap

When two column series share categories, Excel generally places the columns beside each other in a clustered arrangement. That is useful for comparing their heights, but it is not a visual overlay. If you specifically want one column series drawn over another, select a column in the chart, open Format Data Series, and under Series Options adjust Series Overlap. A setting of 100% places the series at the same category position; a lower setting leaves more separation.

Fully overlapping columns can hide the series drawn behind the foreground column. If you use this approach, consider making one series partially transparent, choosing contrasting fills, or using a line for one measure instead. You can also change Gap Width to adjust the space between category groups, but Gap Width controls the spacing of columns, not whether the data series are the same measurement. Check the legend and formatting carefully so viewers can identify which series is in front.

Column overlap is most useful when the purpose is to compare a bar with a target or reference value, not when the reader needs to inspect two amounts independently. For many comparisons, clustered columns or a column-and-line combo chart are clearer and less likely to obscure values.

Format the chart for clear reading

After adding the second series, verify the chart title, legend, axes, and colors. A chart can contain the correct values yet remain confusing if its series names are generic or its units are missing. Use concise series headings in the source table because Excel often uses those headings for the legend. Add axis titles when the units or measures are not obvious from the chart title.

Use distinct, consistent colors and avoid relying on color alone to distinguish important series.
Keep category labels readable; for many dates, reduce label density or widen the chart rather than crowding every label.
Use markers on lines when individual observations matter, but remove visual clutter when there are many points.
Check that the legend order matches the story of the chart and that no series is hidden behind another.
Use a descriptive title, such as Monthly Revenue and Expenses, instead of a generic title such as Chart Title.

To change a title or add labels, select the chart and use the chart elements controls or the options on the Chart Design tab. Exact controls can vary with the chart type. If the chart will be printed or viewed in grayscale, use line styles, markers, or labels as well as color. A clear overlay should make the comparison evident without requiring readers to guess which line or bar represents each data set.

Common overlay problems and fixes

If the second series does not appear, open Chart Design > Select Data and confirm that its value range is correct. Check that the range contains numbers rather than text, does not accidentally include a heading, and covers the intended rows. Also inspect whether the series is formatted in a color that blends into the chart background or is hidden behind a fully overlapping series.

If the horizontal axis shows numbers such as 1, 2, and 3 instead of category names, edit the Horizontal (Category) Axis Labels range in Select Data. If Excel has treated a date or numeric X range as categories when you intended a scatter plot, change the chart type to XY (Scatter) and verify the X and Y ranges for each series.

If one series looks nearly flat, first check whether its scale is much smaller than the other series. A secondary axis may help, but use it only with clear labels. If the two lines appear shifted, verify that their category labels align and that each range begins and ends on the correct rows. If the chart changes unexpectedly when rows are added, convert the source range into an Excel table with Insert > Table; charts based on a table can generally include newly added table rows as the table expands.

When a chart is difficult to interpret even after correcting the data and formatting, the issue may be the comparison itself. Separate charts with a shared time axis can be more readable than forcing unrelated units into one plotting area. The goal is an accurate comparison, not simply putting every measure on top of the same chart.

Frequently Asked Questions

Can I overlay two line charts in Excel?
Yes. Add both data series to one line chart using Chart Design > Select Data > Add. Make sure both series align with the intended category labels, such as the same months or dates.

How do I put two different chart types on one chart?
Select the chart and choose Chart Design > Change Chart Type > Combo. Choose a chart type for each series, then use Secondary Axis for a series only if its scale or units make a shared axis unsuitable.

Can I overlay two data sets with different scales?
Yes, a secondary axis can give one series a separate scale. Label both axes with their units and explain the comparison, because separate scales can make unrelated magnitudes look visually similar.

Why are my Excel columns side by side instead of overlapping?
Excel typically clusters column series by default. Select a series, open Format Data Series, and increase Series Overlap. At 100%, one series may cover the other, so use transparency or a different chart type if both values need to remain visible.

Can I add data from another worksheet?
Yes. In Select Data, add a series and select its name and values from the other worksheet. Keep the category labels aligned with the existing series, and check the chart after confirming the range references.

Does this work in Excel for Mac or Excel for the web?
Excel for Mac has chart tools for adding series and changing chart types, although dialog layouts and ribbon details can differ from Windows. Excel for the web supports many common chart edits, but advanced combo-chart or formatting options may be more limited; use the desktop app if the exact control is unavailable.

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