Measure PR, QRS, and QT on a Scanned EKG in Windows
Chief Executive Officer
When the EKG is a picture, not a live feed
Hospital systems store EKGs in formats you cannot always drop into a dedicated analysis app. Sometimes the strip is a PDF export, a scanned fax, or a screenshot from a viewer. You still need PR, QRS, and QT in milliseconds. Cardio Calipers were built for that: a floating overlay on any Windows image, calibrated to the paper grid on the strip.
This is not a replacement for your EMR or a full EKG interpretation suite. It is a fast on-screen ruler for strips you already have open on the desktop.
Step 1: Open the strip in any viewer
Use whatever you already use: the hospital image viewer, Adobe Reader, IrfanView, even a browser tab. Cardio Calipers float above the window. You do not import the file into our software.
Step 2: Calibrate to 20 mm on the grid
Standard EKG paper uses a 20 mm reference on the vertical grid. Stretch Cardio Calipers across that distance, then choose Set Calibration to 20mm from the menu. After that, interval measurements can read in millimeters, milliseconds, millivolts, or beats per minute depending on the unit you cycle.
Full calibration steps are on How to use Cardio Calipers for EKGs on Windows .
Step 3: Measure PR, QRS, and QT
- PR interval. Span from the start of the P wave to the start of the QRS complex.
- QRS duration. Span the QRS complex from onset to offset.
- QT interval. Span from the start of the QRS to the end of the T wave. Rate correction (QTc) is clinical judgment; Calipers give you the raw QT distance on the strip you are viewing.
- Heart rate. Cycle to Heart Rate and measure P-to-P or R-to-R for beats per minute.
Drag the caliper jaws with the mouse. Use the arrow keys for one-pixel nudges when a wavefront is fuzzy.
Hospital and bulk licensing
We regularly hear from cardiology departments, pediatric teams, and nursing educators who need several seats and pay by purchase order. Download the free Cardio Calipers trial first so your staff can verify the workflow on your actual strips and viewers. Then contact us for purchase orders, check payment, and volume licensing on Windows 10 and 11.
Cardio Calipers also expose a COM interface for teams that embed measurement in custom tools. See the Screen Measurement SDK if your IT group integrates with in-house viewers.
How this compares to EP Calipers
EP Calipers is a strong cross-platform option with modern UI and QTc helpers. Iconico Cardio Calipers target a different habit: a tiny always-on-top Windows overlay on top of whatever viewer you already use, with paper-speed calibration and a long history in hospital PO workflows. Many teams run both depending on the task. We will publish a fuller comparison soon; this post focuses on the Windows screenshot workflow.
Try Cardio Calipers
Download the free trial for Windows 10 and 11, or buy a license on FastSpring.
