What "scale" means in ZeroCount
A drawing's scale is the ratio of drawing distance to real-world distance. A 1:50 drawing means 1 mm on the page represents 50 mm on site.
ZeroCount uses the scale to convert pixel measurements into real-world ones:
- Linear markers — the polyline's pixel length is multiplied by the scale to give metres (or feet).
- Area markers — the polygon's pixel area is multiplied by the scale squared to give m² (or ft²).
Detection and Unit markers don't use the scale — they're counts, not measurements.
If the scale is wrong, every length and area on the drawing is wrong by the same proportion. Setting it correctly is the single most important pre-flight check before any measuring work.
Where the scale lives
Look at the toolbar in Stage 2. To the right of the marker tools sits the scale section:
- A scale ruler icon as a label.
- The Scale System selector — Metric, Architectural, or Both.
- The Group scale dropdown — the current scale, like
1 : 100.
Both controls operate on the active drawing. Other drawings in the project keep their own scales.
Scale System — Metric, Architectural, or Both
The Scale System selector toggles which list of presets is shown in the scale dropdown:
- Metric —
1 : 1,1 : 25,1 : 50,1 : 75,1 : 100,1 : 150,1 : 200,None,Custom. - Architectural —
3' = 1',1' 6" = 1',1' = 1',6" = 1',1-1/2" = 1',1" = 1', and a long tail down to1/128" = 1'. - Both — shows both lists in the dropdown, grouped with headers.
UK and European projects almost always use Metric. US projects use Architectural. Pick Both when you mix project sources, but the dropdown gets long.
The Scale System choice is per-user and per-project. You can also set a default in user preferences.
Setting a scale
Three paths:
- Pick a preset from the dropdown. Quickest path —
1 : 50or1 : 100covers a huge fraction of real drawings. See Scale presets. - Set a custom scale — open the Custom Scale dialog and type a ratio manually. Use this when the drawing is at an unusual scale (1:75 used to be in the preset list, others may not be).
- Calibrate from a known distance — the most accurate path. Pick two points whose real-world distance you know, type the value, and ZeroCount works the scale out. See Calibrating a drawing.
You can do all three from the same scale dropdown — picking Custom opens the Custom Scale dialog with both Manual Entry and Draw & Calibrate tabs.
Per-group scale on Linear and Area
The toolbar scale is the drawing default. Linear and Area groups can also have their own scale that overrides the drawing default — useful when one trade's drawings come at a different scale to another's, or when a detail callout sits at a larger scale inside a smaller-scale main view.
See Linear and area scale (per-group).
What happens when you change scale
If you already have Linear or Area markers on the drawing and you change the scale:
- ZeroCount asks whether to recalculate the existing markers.
- Choose Yes if the previous scale was wrong — values get reinterpreted at the new scale.
- Choose No if the previous values were correct and you only want new markers at the new scale — older markers keep their original numbers.
When in doubt, choose Yes. Markers should consistently reflect one scale at a time.