1 acre = 43,560 sq ft, 1 square mile = 640 acres. Rectangle and triangle area, worked for NY exam lot problems.
1 Acre = 43,560 sq ft · 1 Sq Mile = 640 Acres
Rectangle = Length × Width · Triangle = (Base × Height) ÷ 2
Rectangle = Length × Width · Triangle = (Base × Height) ÷ 2
How to solve it, step by step
- Convert all measurements to feet.
- Compute the area — length × width for a rectangle, or (base × height) ÷ 2 for a triangle.
- Divide by 43,560 to convert square feet to acres, or multiply by 43,560 to go the other way.
Worked examples
A lot measures 100 ft × 200 ft. Area = 100 × 200 = 20,000 sq ft, which is 20,000 ÷ 43,560 = 0.46 acres.
Reversed: 2.5 acres = 2.5 × 43,560 = 108,900 sq ft. Memorise 43,560 — the exam will not give it to you.
What the NY exam actually asks
43,560 is the one number you simply have to know. Questions combine it with rectangle or triangle area, and sometimes with a price per square foot.
Try one yourself
A triangular lot has a base of 300 feet and a height of 290 feet. How many acres is it, to two decimal places?
Show the answer
1.00 acres. Area = (300 × 290) ÷ 2 = 43,500 sq ft. Then 43,500 ÷ 43,560 = 1.00 acres — just under one acre.
Common mistakes
- Not knowing 43,560 from memory.
- Forgetting to halve the product on a triangular lot.
- Mixing units — convert everything to feet before you multiply.
Questions students ask
How many square feet are in an acre?
43,560. This is not provided on the exam, so memorise it.
How many acres are in a square mile?
640 acres, which is also one section in the government survey system.
Related formulas
- The capitalization rate formula
- The T-method
- All 12 formulas — NY Real Estate Math Cheat Sheet
- Real Estate Math Calculator
Practise this. The free 10-question math quiz drills these formulas, and the free timed practice exam puts them under exam conditions.
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