How do you calculate a parking ratio?

Divide the number of spaces by the floor area in thousands of square feet. 100 spaces on a 25,000 sq ft building is 100 ÷ 25 = 4.0 spaces per 1,000 sq ft, or one space per 250 sq ft. In reverse, spaces = ratio × area ÷ 1,000.

How do I convert "1 space per 300 sq ft" to a ratio per 1,000 sq ft?

Divide 1,000 by the square feet per space: 1,000 ÷ 300 = 3.33 spaces per 1,000 sq ft. 1 per 250 is 4.0, 1 per 200 is 5.0 and 1 per 100 is 10.0.

How many ADA accessible parking spaces are required?

Under Table 208.2 of the 2010 ADA Standards: 1 for 1–25 spaces, 2 for 26–50, 3 for 51–75, 4 for 76–100, 5 for 101–150, 6 for 151–200, 7 for 201–300, 8 for 301–400, 9 for 401–500, 2% of the total for 501–1,000, and 20 plus 1 for each 100 (or fraction) over 1,000. Hospital outpatient lots need 10% of patient and visitor spaces and rehabilitation or outpatient physical therapy facilities 20%.

How many van-accessible spaces are required?

At least one of every six accessible spaces, or fraction of six, must be van-accessible (ADA 208.2.4). A lot needing 7 accessible spaces therefore needs 2 van spaces; one needing 4 needs 1.

What is a typical parking ratio for office, retail and industrial buildings?

Many US zoning codes require roughly 3 to 4 spaces per 1,000 sq ft for general office (1 per 250–300 sq ft), 4 to 5 for retail, about 5 for medical office, around 10 for sit-down restaurants and 1 to 2 for industrial and warehouse space. Rules vary widely, and a growing number of cities, including Buffalo, Minneapolis and Austin, no longer set minimums.

How much land does a parking space need?

A typical 9 × 18 ft stall is 162 sq ft, but with its share of drive aisles a surface lot needs about 300–350 sq ft per space. 100 spaces therefore take roughly 30,000–35,000 sq ft, or 0.69–0.80 acres, before landscaping and setbacks.

What floor area should I use, gross or net?

Use the exact area definition attached to the ratio you are applying. A code or lease may specify gross floor area, gross leasable area, net rentable area or defined exclusions. Mixing a rate from one rule with a different area definition gives a misleading result.

Parking Ratio Calculator

Parking ratio = spaces ÷ (floor area ÷ 1,000). Find a building ratio, turn a zoning rule like "1 space per 300 sq ft" into a space count, estimate surface lot area, and get the ADA accessible and van spaces required.

Inputs

Area & ratio basis

Building Area (sq ft)

Calculation Mode

Find ratio from space count Find required spaces from ratio

Number of Parking Spaces

Result

Enter values and click Calculate.

ADA Accessible Spaces

2010 ADA Standards 208.2 apply to the total spaces in each parking facility. Fractions round up (104.2).

Total spaces in the lot

Facility

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accessible

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van-accessible

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standard accessible

Before Using This for Compliance

Confirm the land-use category and whether the rate is a minimum, maximum, or target.
Use the specified area definition: GFA, GLA, net rentable area, or another defined basis.
Check the jurisdiction's fractional-space rounding rule and any exemptions or reductions (shared parking, transit proximity).
Count accessible spaces per parking facility, and check state codes that may require more than the ADA minimum.

Typical Parking Ratios by Land Use

Common US zoning minimums, shown as examples. Local codes vary widely; ITE Parking Generation reports observed peak demand, often lower.

Land use	1 space per	Per 1,000 sq ft	Per 100 m²
General office	300 sq ft	3.33	3.59
Medical / dental office	200 sq ft	5.00	5.38
Retail store	250 sq ft	4.00	4.31
Restaurant, sit-down	100 sq ft	10.00	10.76
Fitness / health club	200 sq ft	5.00	5.38
Industrial / manufacturing	500 sq ft	2.00	2.15
Warehouse / distribution	1,000 sq ft	1.00	1.08

Housing is usually set per dwelling unit (often 1–2 spaces per unit), not per floor area.

ADA Table 208.2: Minimum Accessible Spaces

Van-accessible: at least 1 of every 6 accessible spaces or fraction of 6 (208.2.4).

Total spaces in facility	Accessible	Of which van
1–25	1	1
26–50	2	1
51–75	3	1
76–100	4	1
101–150	5	1
151–200	6	1
201–300	7	2
301–400	8	2
401–500	9	2
501–1,000	2% of total	1 per 6
1,001+	20 + 1 per 100 over 1,000	1 per 6

Summary

A parking ratio relates parking spaces to building area, usually spaces per 1,000 sq ft (or per 100 m²). Zoning codes often write the same rule as "1 space per N sq ft", which is a ratio of 1,000 ÷ N per 1,000 sq ft: 1 per 300 sq ft is 3.33 per 1,000. This calculator works both ways, keeps the exact figure separate from the rounded-up whole-space count, estimates surface lot area at 300–350 sq ft per space (stall plus its share of aisles), and applies the 2010 ADA Standards Table 208.2 to the total, including the 1-in-6 van-accessible rule and the 10% and 20% rules for outpatient and rehabilitation facilities. Typical ratios by land use are examples only; the controlling local code defines the area basis, rate, rounding and any reductions.

How it works

Choose square feet (spaces per 1,000 sq ft) or square metres (spaces per 100 m²) and enter the building area.
Ratio mode: enter the number of spaces to get spaces per 1,000 sq ft and the floor area per space.
Required-spaces mode: pick a land use or type a ratio, either as spaces per 1,000 sq ft or as "1 space per N sq ft". Required spaces = ratio × area ÷ 1,000, rounded up for planning.
The result also estimates surface lot area at 300–350 sq ft (28–33 m²) per space including drive aisles.
The ADA panel takes the total spaces (filled in automatically) and returns accessible spaces from Table 208.2, with at least 1 of every 6 (or fraction of 6) van-accessible.

Use cases

Checking a 25,000 sq ft office against a 1 per 300 sq ft code (84 spaces) or a 4 per 1,000 lease target (100 spaces).
Comparing a property's parking ratio with typical figures for office, retail, medical or industrial uses.
Converting a "1 space per 250 sq ft" ordinance into a ratio per 1,000 sq ft and a whole-space count.
Estimating how much land a surface lot needs before a site plan is drawn.
Working out ADA accessible and van-accessible spaces for a lot of any size, including hospital outpatient lots.
Converting a metric (per 100 m²) parking standard into a space count.

Frequently Asked Questions

Last updated: 2026-10-10 · Reviewed by Nham Vu