Free XMR Chart Generator (Process Behavior Chart Maker)
Data input
What is an XMR chart?
An XMR chart is a pair of control charts used to track a metric over time. The “X” chart plots individual values. The “mR” chart plots the moving range — the absolute difference between consecutive data points.
Together they answer one question: is this data point normal variation, or did something actually change?
Most line charts and bar charts can’t tell you this. They show trends but not significance. XMR charts add natural process limits (UNPL and LNPL) calculated from your own data. Points inside the limits are routine variation. Points outside are signals worth investigating.
The method was developed by Walter Shewhart in the 1920s for manufacturing quality control. It works equally well for business metrics like revenue, conversion rates, support tickets, or deployment frequency.
How this tool works
- Enter your data as label-value pairs, or paste from a spreadsheet
- Click “Generate XMR chart” to calculate control limits and render both charts
- The X chart shows your data points with the mean (green dashed line) and upper/lower natural process limits (red dashed lines)
- The mR chart shows the variation between consecutive points, with its own mean and upper range limit
- Points outside the limits are highlighted in red — these are signals
- Download the chart as a PNG for reports or presentations
The tool pre-loads example data so you can see what a chart looks like before entering your own numbers.
How to read your chart
On the X chart:
- The green dashed line is the mean of your data
- The red dashed lines are the natural process limits (UNPL above, LNPL below)
- Red dots are signals — points outside the limits
On the mR chart:
- Each point shows how much the metric changed from the previous period
- The green dashed line is the average moving range
- The red dashed line is the upper range limit
- Red dots indicate unusually large shifts between consecutive periods
If all points fall within the limits on both charts, your process is stable. Variation is present but predictable.
If you see signals, something changed. The chart doesn’t tell you why — it tells you when. Your job is to investigate what happened at that point.
When to use an XMR chart
XMR charts work for any metric measured over time where you get one value per period:
- Monthly revenue or MRR
- Weekly signups or active users
- Daily support ticket volume
- Sprint velocity or cycle time
- Conversion rates by week or month
- NPS or CSAT scores over time
They are especially useful when you want to stop reacting to noise. A 10% drop in weekly signups feels alarming. An XMR chart tells you whether it’s within normal range or a genuine change worth acting on.
Frequently Asked Questions
What is an XMR chart?
An XMR chart (also called a process behavior chart or I-MR chart) is a control chart that plots individual data points over time alongside a moving range. It calculates natural process limits to distinguish normal variation from genuine signals of change. The X chart shows your data with upper and lower limits; the mR chart shows the variation between consecutive points.
How many data points do I need?
You need a minimum of 2 data points to calculate moving ranges, but 12-20 points give more stable limits. More data points mean more reliable limits, but even with 5-8 points you can start identifying obvious signals.
Why not use standard deviation for control limits?
Standard deviation overestimates natural variation because it is inflated by the very signals you are trying to detect. XMR charts use the average moving range method (multiplied by 2.66), which estimates variation from consecutive differences only. This gives tighter, more sensitive limits.