AmpliaMeasure Distance on a Photo
Turn any photo into a tape measure. Calibrate once against a dimension you already know, then read real distances and lengths straight off the image — free, in your browser, with no upload.
How it works — calibrate once, measure everything
Two steps stand between a photo and real measurements.
Upload a photo and mark one known distance
Drop in any photo, drawing, or plan — or start with the built-in sample image. Place two calibration points on a distance you already know in the real world (say, a door that is 2 m tall) and enter that value and unit. This sets the scale for everything else.
Draw lines and paths — lengths appear instantly
Switch to the Line or Polyline tool and click to place points. Real-world lengths show up as labels on the canvas and update live as you drag points to fine-tune them.
Calibrate once, and every line you draw afterwards is already a real measurement — you are halfway there before you start.
Two tools for distance
Straight Line — point-to-point distance
Click two points and read the direct distance between them. The go-to tool for a single wall, a window width, or the gap between two corners.
Polyline — total length along a path
Click each point along a multi-segment route to get the length of every segment plus the running total. Ideal for cable runs, baseboards, or a route traced on a map.
When photo distance measurement is accurate
Works well
- Flat, front-on photos taken square to the surface
- Floor plans, blueprints, and scanned technical drawings
- Objects on the same flat plane as your calibration reference
- Screenshots of maps with a visible scale bar
Less reliable
- Perspective shots where the subject recedes into depth
- Objects at a different distance than the calibration reference
- Curved or three-dimensional surfaces
- Wide-angle or fisheye photos with visible lens distortion
Measurements are accurate for objects on the same flat plane as your calibration reference. Objects at different depths, or a photo taken at a steep angle, will introduce error.
Supported units
Measure and convert across every unit Amplia supports, grouped by system and subsystem.
Distance
Metric
| Symbol | Name |
|---|---|
| nm | nanometre |
| μm | micrometre |
| mm | millimetre |
| cm | centimetre |
| m | metre |
| km | kilometre |
Imperial
| Symbol | Name |
|---|---|
| in | inch |
| ft | foot |
| yd | yard |
| mi | mile |
| mil | thou |
Nautical
| Symbol | Name |
|---|---|
| ftm | fathom |
| cb | cable |
| nmi | nautical mile |
Astronomical
| Symbol | Name |
|---|---|
| AU | astronomical unit |
| ly | light-year |
| pc | parsec |
Typography
| Symbol | Name |
|---|---|
| pt | point |
| pc | pica |
What people measure with it
Walls & windows from site photos
Grab wall runs and opening widths from a photo of the room, calibrating on a door or a brick course.
Furniture from listing photos
Check whether a sofa or table will fit before you buy, using a known dimension already in the shot.
Route length on a map
Trace a path with the Polyline tool on a map screenshot, calibrating against the scale bar, to get total distance.
Part dimensions on a drawing
Read lengths off a scanned technical drawing or blueprint using its printed scale as the reference.
Frequently asked questions
?How accurate is distance measured from a photo?
Very accurate for objects on the same flat plane as your calibration reference, photographed square-on — floor plans, scanned drawings, and front-on shots are ideal. Perspective, depth differences, curved surfaces, and wide-angle lens distortion all reduce accuracy.
?Can I measure a curved or multi-segment path?
Yes. The Polyline tool lets you click point after point along a path and gives you both the length of each segment and the running total — handy for cable runs, baseboards, or a route traced on a map.
?What distance units are supported?
Results can be shown in metric (mm, cm, m, km and more), imperial (inch, foot, yard, mile), nautical (fathom, cable, nautical mile), astronomical (astronomical unit, light-year, parsec), and typography (point, pica) units. Values are converted automatically as you measure.
?Do I need to install anything or sign up?
No. Amplia runs in your browser — nothing to install. You can upload a photo, calibrate, and measure with the Line tool without an account.
?Is my photo uploaded to a server?
Not when you measure without an account. Your image stays on your device and all measuring happens locally in the browser. It is only stored in the cloud if you choose to sign in and save your work as a project.
Start measuring distances — free
Open the tool and try it on the built-in sample image — no sign-up, and your photo never leaves your device.