Quick guide
How to use this calculator
- Enter amounts from the same property scenario and use consistent periods and units.
- Use visitor-entered rates and allowances from your own documents rather than assuming a local rule.
- Review the component results and the calculator-specific decision boundary before acting.
Calculation method
Calculation method
Reported gross internal area = sum of entered internal floor extents − sum of entered exclusions.
Entered fixed decimals remain exact through rational arithmetic. Planar distance outputs that require square roots use bounded numerical evaluation. Values round only for display, and unsupported or undefined states return an explicit message.
Worked example
Worked example
Internal floor extents of 1,000 and 950 less exclusions of 20 and 10 report 1,920 area units.
Reported gross internal area = sum of entered internal floor extents − sum of entered exclusions.
Supported inputs
Precision and limits
International scope
No currency, market price, interest rate, tax, tenancy rule, planning code, lender policy, or measurement definition is supplied automatically.
Scenario, not a decision
Results are arithmetic scenarios from visitor-entered values—not an appraisal, loan approval, legal interpretation, planning determination, forecast, or professional recommendation.
Precision and privacy
Inputs accept bounded plain decimals and remain in this browser. The engine prevents invalid denominators and misleading non-finite results.
Calculator-specific boundary
Gross internal area, IPMS 2, and other national conventions use different extents and inclusions. Record the standard, purpose, measurement date, and every exclusion.
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