# Usable Acreage Calculator: Net Developable Land | FOUND

Estimate the usable acres on a tract after floodplain, wetlands, steep slopes, easements, and setbacks. A fast first read before you order a survey.

Canonical: https://lotsfound.com/tools/usable-acreage-calculator/

## Gross acres, minus what you cannot use

Enter the tract size and the constraints you know about. The calculator subtracts them and applies a setback allowance to estimate usable land.

## How the estimate works

1. Constrained land is the sum of floodplain, wetlands, steep slopes, and easements.
2. Remaining land is gross acres minus constrained land.
3. Usable land is remaining land reduced by the setback and buffer allowance.

## Where the numbers come from

Floodplain comes from FEMA flood maps. Wetlands come from federal wetland maps. Slopes come from elevation data. Easements come from the deed and plat. Each one is public, and each one has limits: maps lag the ground, and only a survey or a delineation sets the final lines.

## Questions

### What is the difference between gross and usable acreage?

Gross acreage is everything inside the parcel lines. Usable acreage is what is left after the land you cannot build on or cannot disturb.

### How much of a tract is usually usable?

It varies from nearly all of it to less than half. River frontage, wetlands, and steep terrain are the usual reasons a tract shrinks.

### Is this a substitute for a survey?

No. It tells you whether a tract is worth a survey and a wetland delineation, and roughly what to expect from them.

Transactions are handled through a licensed North Carolina real estate brokerage.