Parking Ratio Calculator

About Parking Ratio Calculator

How to Calculate Required Parking Spots

Parking requirements are determined by multiplying your building's size (or unit count) by the applicable parking ratio for that building type. Most municipalities use ratios based on the ITE Parking Generation Manual as a baseline, then adjust for local conditions.

Required Spaces = Building Size (in 1,000 sq ft) × Parking Ratio
For unit-based types: Required Spaces = Number of Units × Ratio per Unit

Step 1: Select your building's usage type (office, retail, residential, etc.).
Step 2: Enter the gross floor area in square feet. For residential, hotel, or similar types, also enter the number of units.
Step 3: Choose whether to include ADA accessible parking and set EV charging percentage.
Step 4: Review the minimum, typical, and maximum parking requirements along with a detailed breakdown.

Understanding Parking Ratios

Parking ratios express how many parking spaces are needed per unit of building measurement. The Institute of Transportation Engineers (ITE) publishes widely-used parking generation rates based on field studies of actual parking demand across thousands of sites.

Minimum ratio: The lower end, suitable for urban areas with good transit access or shared parking agreements.
Typical ratio: The most commonly observed demand, used as the default in most zoning codes.
Maximum ratio: The upper end, for suburban locations with limited transit and high auto dependency.

Local zoning codes may set their own minimums or maximums. Always check with your local planning department for specific requirements.

ADA Accessible Parking Requirements

The Americans with Disabilities Act (ADA) requires a minimum number of accessible parking spaces based on the total number of spaces provided. The requirements follow a tiered system:

1-25 total spaces: 1 accessible space
26-50 total: 2 accessible spaces
51-75 total: 3 accessible spaces
76-100 total: 4 accessible spaces
101-150 total: 5 accessible spaces
151-200 total: 6 accessible spaces
201-500 total: 7-9 accessible spaces
501-1000 total: 2% of total
Over 1000: 20 + 1 per 200 additional spaces

EV Charging Parking Requirements

Many jurisdictions now require a percentage of parking spaces to support electric vehicle charging. Requirements typically fall into three tiers:

EV-Ready: Conduit and electrical panel capacity installed (no charger) - typically 10-20% of spaces.
EV-Capable: Wiring run to the space, ready for charger installation - typically 5-10% of spaces.
EV-Installed: Charger actively installed and operational - typically 2-6% of spaces.

California's CALGreen Code, for example, requires 10% EV-capable spaces for new non-residential buildings. Check your local building code for specific requirements.

Frequently Asked Questions

How do I calculate the number of parking spots needed for my building?

To calculate parking requirements, you need your building's gross floor area (in square feet) and usage type. Multiply the floor area (in thousands of sq ft) by the parking ratio for your building type. For example, a 50,000 sq ft general office typically needs 3.3 spaces per 1,000 sq ft, resulting in 165 parking spaces.

What are standard parking ratios by building type?

Standard ITE parking ratios vary by use: General Office 2.5-4.0 per 1,000 sq ft, Retail 3.0-5.0, Restaurant 8.0-18.0, Residential 1.0-2.25 per unit, Hotel 0.7-1.3 per room, Industrial 0.5-1.5, Medical Office 3.5-6.5, and Hospital 2.5-5.0 per bed. Local zoning codes may adjust these ranges.

How many ADA accessible parking spaces are required?

ADA requirements scale with total parking: 1-25 total spaces need 1 accessible space, 26-50 need 2, 51-75 need 3, 76-100 need 4, 101-150 need 5, 151-200 need 6, 201-300 need 7, 301-400 need 8, 401-500 need 9, and 501-1000 need 2% of total. Above 1,000, add 1 accessible space for every 200 additional spaces.

What percentage of parking should be EV charging?

EV charging requirements vary by jurisdiction. California requires 10% EV-capable spaces for new construction. Many cities require 2-6% of spaces to have EV chargers installed, with an additional 10-20% of spaces to be EV-ready (conduit installed). A common starting point is 5% of total spaces.

How much land area is needed per parking space?

A surface parking lot requires approximately 300-400 square feet per space (including drive aisles), with 350 sq ft being a common average. Structured (multi-level) parking uses approximately 200 sq ft per space per level. These estimates help in planning site layout and land acquisition.

Additional Resources

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by miniwebtool team. Updated: Feb 9, 2026