Formula & constants
Stall yield depends on the parking module — stall depth plus aisle width — and on curb length per car, which is stall width divided by the sine of the parking angle. That is why angled parking fits fewer cars per linear foot of curb, not more: at 45° each 9-foot stall consumes about 12.7 feet of curb. Efficient lots land near 300–350 sq ft per car including aisles. All default values are editable — when your supplier's data sheet or local code says otherwise, use that number.
Where this fits in your project
This tool is one step in a bigger job. Once you have these numbers, parking lot paving estimate tool (Parking Lot Paving Calculator), then ada parking compliance estimate tool (ADA Parking Compliance Calculator). For the full sequence see the project workflows, compare approaches on the comparison pages, and check local factors in the state guides.
Frequently asked questions
How many parking spaces fit per acre?
Roughly 120 to 145 stalls per acre for efficient perpendicular layouts, which works out to about 300 to 350 square feet per car once aisles and circulation are included.
Does angled parking save space?
No, and this surprises people. Stall depth stays around 18 to 19 feet regardless of angle, while the curb length each car occupies grows as stall width divided by sin(angle). Angled bays fit fewer cars per linear foot but allow narrower one-way aisles.
What aisle width do I need?
About 24 feet for two-way perpendicular parking, 20 feet for one-way, roughly 18 feet at 60 degrees and around 13 feet at 45 degrees.
What is a standard stall size?
Nine feet by eighteen feet is the common US standard. Compact stalls run about 8.5 by 16 to 17 feet and are capped at 30% of the total under many zoning codes.
How many ADA spaces will my lot need?
It follows the ADA scoping table by total stalls — one for lots up to 25, scaling to nine for 401–500, then 2% up to 1,000. Calculate it separately for each parking facility on the site.
Last verified: — See our methodology.
Planning estimates only — confirm quantities with suppliers and local code before ordering.