Property Constraint Score: what the 0-100 number means

MapMyLot's constraint score reduces a property's mapped planning constraints to a single 0-100 number - fast to scan across a shortlist, but only as good as what it actually measures. This page explains the calculation and, just as importantly, what the number is not.

What the score looks like

The badge shows the score and a plain-English band label. The free view names any easements and protected areas found on that parcel and counts the rest; Pro and the property report name every layer found - in the example above, a Brisbane CBD building scores 75 ("Some constraints") because Electricity and Heritage both intersect the site.

How it's calculated

Every property starts at 100. Each of 7 mapped constraint layers present on the parcel subtracts a fixed weight: flood zones and bushfire-prone areas each subtract 25 points, coastal and erosion hazards 20, protected areas and electricity corridors each 15, easements 12, and heritage listings 10. In Queensland, flood subtracts 10 instead of 25: the only statewide flood map there is the Queensland Floodplain Assessment Overlay, a broad screening layer the Queensland Government says is not intended to predict flooding for a specific lot, so it is a prompt to check the council's flood search rather than a finding. A layer counts as present once it covers at least 10 m² or 1% of the lot, whichever is smaller, so a hairline sliver along a boundary costs nothing. The deductions stack - a parcel affected by three different constraints subtracts all three weights, which is why a score can drop well below what any single constraint would suggest on its own.

The four bands

Scores fall into four labelled bands: 85 and above is Low constraint (green), 60 to 84 is Some constraints (amber), 30 to 59 is Significant constraints (orange), and below 30 is Highly constrained (red). The bands are a readability aid over the same underlying number, not a separate judgement.

What the score is not

To be direct about the limits: this is a summary of mapped planning constraints, never a safety rating. A high score does not certify a property is safe to build on or free of risk - it means the mapped constraints produced relatively small weighted deductions, within whatever coverage currently exists for that jurisdiction. It does not check zoning permissions, local council heritage overlays, soil conditions, or anything outside the 7 mapped layers. Flood, bushfire and coastal and erosion hazards in particular are hazard layers reported as present-or-absent, not folded into a false "safe" reading elsewhere on MapMyLot - the score is one summary view of the same underlying data, not a new claim.

When no score shows

The score needs at least 3 of the 7 constraint layers loaded for a jurisdiction before it calculates at all - below that threshold MapMyLot shows nothing, rather than a number built on too little data to mean anything. This is most likely in jurisdictions with only 1-2 of the 7 layers currently live.

Where the score is useful

The score's real value is comparative: scanning several candidate properties at once, or narrowing a Shortlist Builder search, without opening each property's individual overlay breakdown first. For a specific decision - a purchase, a build, or an insurance question - the individual constraint layers and an appropriate professional are always the next step, not the summary number.

Compare the coverage as well as the score

Compare the layers checked before comparing two scores, especially across jurisdictions. A property with fewer available datasets may have fewer recorded deductions simply because less is mapped. Review each relevant layer before using the score to shortlist a property.