Measure distances on images/text/PDFs (pixels), with optional conversion to ms & bpm.
Content Upload
- PDF Files: Drag & drop or use Browse Files. Navigate multiple pages with arrow buttons.
- Images/Text: Drag & drop, paste, or browse files.
- Clear: Use "Clear Calipers" to reset measurements.
Caliper Controls
- Add: Use Add Caliper for a standard interval, Add Rhythm Caliper for marching measurements, or QT/QTc for a corrected QT interval.
- Rhythm: March out waves with ten additional evenly spaced calipers.
- Move/Resize: Drag center square to move, vertical lines to resize
- Keyboard: Tab to a caliper handle, then use arrow keys to adjust by 1 px or Shift + arrow to adjust by 10 px. Press Delete to remove that caliper.
- Remove: Right-click any part of a caliper
- Color: Choose a labeled color, then add a caliper. Existing calipers retain their original colors.
Reference & Units
- Add Reference: Click "Add Reference", set the ms value in the dropdown
- Units: With a reference — ms/bpm; without — pixels (px)
QT/QTc
- Measure: Add QT/QTc, then resize its primary interval across the QT measurement.
- Correct: Add a reference and enter either Rate (bpm) or RR interval (ms). Only one QT/QTc caliper is active; adding another replaces it.
- Bazett formula: QTc = QT / √RR, with QT and QTc displayed in milliseconds and RR expressed in seconds. Bazett correction may over- or under-correct at extreme heart rates and does not replace clinical interpretation.
Note: All operations are performed locally in your browser. No content is uploaded. Siteimprove records aggregate visits and caliper-creation counts by tool type and palette color, never your content or measurements. Download the offline version.