A useful blood pressure graph uses real measurement dates and states whether each point is a reading or a summary. Label systolic, diastolic and the units, and make missing sessions visible. Keep the underlying table so the reader can inspect what the picture leaves out.

Say what you plotted

A point might be one measurement, a session average or a daily average. Those are different summaries. Name the choice rather than letting the shape imply that every point represents the same amount of information.

The fictional example below uses the evening sessions from our seven-day sample. Each plotted value averages that session's two measurements. There was no evening session on 10 October.

Fictional evening session averages, 7–13 October 2026Systolic values are 132, 129, 127, missing, 131, 125 and 129 mmHg. Diastolic values are 84, 83, 81, missing, 85, 79 and 83. Lines break on 10 October; the table below contains the same values.1401108070mmHg7 Oct8 Oct9 Oct10 Oct11 Oct12 Oct13 OctNo PM sessionSolid: systolicDashed: diastolic
Original teaching illustration, not a BPBook screen or target range. Both series use mmHg; the axis shown begins at 70. Scroll sideways on a small screen to inspect the dates.
Read the values behind this chart
Fictional evening averages · two measurements per recorded session
October dateSystolicDiastolic
713284
812983
912781
10MissingMissing
1113185
1212579
1312983

Make missing time visible

Do not insert zero or invent a measurement to fill a gap. In this illustration, the absent session has a labelled space and the lines stop on either side.

Charting software may connect observations across unrecorded dates. When it does, keep the missing interval explicit in a note and show the source table. Consecutive dots in a graph do not necessarily mean consecutive monitoring sessions.

Use real dates and times when you have them. An evenly spaced list numbered 1 to 20 can conceal whether it covers a few days or several months.

Give the reader enough context to compare it

Show the period, unit and series labels. Identify any equipment change or change in the recording routine with a factual note. If you display a clinician-agreed reference range, label its source and purpose rather than silently applying a universal target.

The line's direction does not establish why the readings changed or whether a treatment worked. Bring the underlying record and questions to the care team.

Keep an editable record as well as a picture

The graph maker accepts pasted readings or a CSV and can export PNG, SVG or PDF. Review its dates and values before exporting. A picture helps someone read the pattern; the source rows let them inspect the details.

For an appointment document containing both, use the report generator and check the finished PDF. Keep the CSV and notes too, so a later date-range change does not require reconstructing your history from the image.

Frequently asked questions

Should I join the line across a missing session?

Make the missing interval explicit. This example breaks the line and labels the gap; keep the source table available even if another chart connects observations.

Does a falling line show that treatment worked?

The direction alone does not establish a cause. Share the dated measurements, conditions and questions with your healthcare professional.

Sources

Sources and public tool descriptions checked 20 October 2026. The chart design and sample calculations are original teaching examples; they do not interpret someone's health.