What is the difference between Clear Opening, Shutter Size, Frame Outer, and Rough Masonry Opening?

• **Clear Opening (Passage Width)**: The net unobstructed walkthrough dimension between frame jambs with the door open at 90°. • **Shutter / Leaf Size**: The physical door panel that fits into the frame rebate. (Shutter Width = Clear Width + 2 × Rebate Depth). • **Frame Outer Size (Chowkhat Outer)**: The total outer dimension of the door frame box. (Frame Outer Width = Clear Width + 2 × Frame Thickness). • **Rough Masonry Opening**: The structural opening constructed by masons from lintel to finished floor. (Rough Width = Frame Outer Width + 2 × Shim Gap [typically 10mm to 15mm for expanding foam/grout alignment]).

What are the standard door sizes in Indian residential architecture (NBC 2016)?

• **Main Entrance Door (D1)**: 1000mm × 2100mm (3'3" × 7'0") or 1200mm × 2400mm (4'0" × 8'0") for grand villa pivot doors. • **Internal Bedroom Doors (D2)**: 900mm × 2100mm (3'0" × 7'0") for smooth furniture and mattress transit. • **Bathrooms / Toilets / Utility (D3)**: 750mm × 2100mm (2'6" × 7'0") or 800mm × 2100mm (2'8" × 7'0"). • **Balcony / French Doors**: 1500mm to 2400mm (5'0" to 8'0") 2-track or 3-track sliding UPVC/Aluminium doors.

How is required exit door width calculated based on occupant load (NBC 2016 & NFPA 101)?

Egress width is calculated by multiplying the occupant load by the egress factor: • **Non-Sprinklered Buildings**: 5.08 mm (0.2 inches) per occupant. For example, an assembly room with 300 occupants requires $300 \times 5.08 = 1,524\text{ mm}$ (1.52m) of aggregate exit width. • **Sprinklered Buildings (NFPA 13 / NBC)**: 3.81 mm (0.15 inches) per occupant ($300 \times 3.81 = 1,143\text{ mm}$). Additionally, NBC requires minimum doorway units: 1 exit door for $\le 50$ persons, min 2 separate exit doors for 51–500 persons, 3 exits for 501–1000 persons, and 4 exits for $>1000$ persons.

What is the ADA minimum clear door width requirement for wheelchair accessibility?

Under ADA Standards Section 404 and CPWD Harmonized Guidelines for Barrier-Free Environment, doorways must provide a minimum **Clear Opening Width of 32 inches (813 mm)** measured between the face of the door and the stop with the door leaf open at 90 degrees. Doors on an accessible route should also provide a level threshold ($le 1/2"$ / 12.7mm with 1:2 bevel) and minimum 18" (457mm) latch-side pull clearance.

When is a double-leaf door required instead of a single-leaf door?

A single door leaf should generally not exceed **1050mm to 1100mm (3'6" to 3'8")** in width because oversized single leaves put excessive torque on hinges, cause sagging over time, and require excessive swing space. Any opening between **1200mm and 2400mm (4'0" to 8'0")** should utilize double equal leaves or a 1.5 unequal leaf (active leaf 800–900mm + passive slave leaf 350–450mm).

When are panic exit hardware (crash bars) mandatory on doors?

Per NBC 2016 Part 4 and NFPA 101 Life Safety Code, panic exit hardware (crossbar or touchpad crash bar) is mandatory on all exit doors serving **Assembly occupancies (Group D)**, **Educational spaces (Group B)**, and any room or space with an occupant load of **50 persons or more**. Panic doors must unlatch with no more than 67 N (15 lbf) of push force and must swing outward in the direction of escape travel.

How many hinges are required based on door leaf height and weight?

• **3 Hinges (Standard)**: For door leaves up to 2100mm (7'0") in height and weight up to 45 kg (standard flush and light wood doors). • **4 Hinges (Heavy Duty)**: For door leaves exceeding 2100mm (e.g. 2400mm / 8'0" doors) or heavy solid teak/fire-rated metal leaves weighing 45 kg to 100 kg. Hinges should be Grade 304 Stainless Steel Ball Bearing type (minimum 4" × 3" × 3mm or 5" × 3.5" × 3.5mm).

Door Size Calculator

Calculate architectural door dimensions, clear walkthrough openings, rough masonry framing, and occupant egress capacity per NBC 2016, IBC, NFPA 101, and ADA standards with interactive 2D CAD elevation studio.

⚡ Interactive Calculation Engine Active

Please enable JavaScript in your browser to run live computations, 2D envelope diagrams, and export PDF reports.

How to Use Door Size Calculator

Select your preferred measurement unit: Millimeters (mm), Centimeters (cm), Inches (in), or Feet (ft).
Choose a standard architectural door preset (e.g. D1-Main Entrance, D2-Bedrooms, D3-Bathrooms, D4-Classroom, D5-Hospital Stretcher) or enter custom dimensions.
Input Clear Usable Opening Width and Height (unobstructed walkthrough dimensions at 90° open position).
Configure Frame (Chowkhat) thickness (50mm–100mm), Shutter stop rebate depth (10mm–15mm), and Masonry shim grout gap (10mm).
Select your Building Occupancy Class per NBC 2016 / IBC (Residential Group A, Educational Group B, Institutional Group C, Assembly Group D, Business Group E, Mercantile Group F, Industrial Group G, Storage Group H).
Enter Design Occupant Load (number of persons) and toggle automatic fire sprinkler coverage to verify life safety egress width.
Choose Door Leaf Style: Single Swing, Double Equal Leaf, 1.5 Unequal Leaf, or Grand Pivot Door.
Select Door Core Material (Solid Teak, Flush Door, Hollow Pressed Metal, Fire-Rated Insulated Steel) to calculate estimated leaf weight and hinge specifications.
Inspect the live 2D Architectural CAD Studio (Elevation View and Floor Plan Swing Clearance with wheelchair turning radius).
Click '+ Add Current Door' to build your multi-door Project Door Schedule and download your certified PDF Schedule Certificate or copy the WhatsApp audit summary.

NBC 2016 Minimum Doorway Width Standards by Occupancy Group

Door Framing Tolerance & Rough Opening Formula

To calculate the masonry opening for structural lintel casting: $\text{Rough Opening Width} = \text{Clear Width} + 2 \times \text{Frame Thickness} + 2 \times \text{Shim Gap (10mm)}$ $\text{Rough Opening Height} = \text{Clear Height} + \text{Frame Thickness} + \text{Shim Gap (10mm)}$ *Note: Modern interior door frames omit the bottom sill frame to ensure zero trip hazard and ADA wheelchair accessibility.*

Frequently Asked Questions

What is the difference between Clear Opening, Shutter Size, Frame Outer, and Rough Masonry Opening?: • **Clear Opening (Passage Width)**: The net unobstructed walkthrough dimension between frame jambs with the door open at 90°. • **Shutter / Leaf Size**: The physical door panel that fits into the frame rebate. (Shutter Width = Clear Width + 2 × Rebate Depth). • **Frame Outer Size (Chowkhat Outer)**: The total outer dimension of the door frame box. (Frame Outer Width = Clear Width + 2 × Frame Thickness). • **Rough Masonry Opening**: The structural opening constructed by masons from lintel to finished floor. (Rough Width = Frame Outer Width + 2 × Shim Gap [typically 10mm to 15mm for expanding foam/grout alignment]).
What are the standard door sizes in Indian residential architecture (NBC 2016)?: • **Main Entrance Door (D1)**: 1000mm × 2100mm (3'3" × 7'0") or 1200mm × 2400mm (4'0" × 8'0") for grand villa pivot doors. • **Internal Bedroom Doors (D2)**: 900mm × 2100mm (3'0" × 7'0") for smooth furniture and mattress transit. • **Bathrooms / Toilets / Utility (D3)**: 750mm × 2100mm (2'6" × 7'0") or 800mm × 2100mm (2'8" × 7'0"). • **Balcony / French Doors**: 1500mm to 2400mm (5'0" to 8'0") 2-track or 3-track sliding UPVC/Aluminium doors.
How is required exit door width calculated based on occupant load (NBC 2016 & NFPA 101)?: Egress width is calculated by multiplying the occupant load by the egress factor: • **Non-Sprinklered Buildings**: 5.08 mm (0.2 inches) per occupant. For example, an assembly room with 300 occupants requires $300 \times 5.08 = 1,524\text{ mm}$ (1.52m) of aggregate exit width. • **Sprinklered Buildings (NFPA 13 / NBC)**: 3.81 mm (0.15 inches) per occupant ($300 \times 3.81 = 1,143\text{ mm}$). Additionally, NBC requires minimum doorway units: 1 exit door for $\le 50$ persons, min 2 separate exit doors for 51–500 persons, 3 exits for 501–1000 persons, and 4 exits for $>1000$ persons.
What is the ADA minimum clear door width requirement for wheelchair accessibility?: Under ADA Standards Section 404 and CPWD Harmonized Guidelines for Barrier-Free Environment, doorways must provide a minimum **Clear Opening Width of 32 inches (813 mm)** measured between the face of the door and the stop with the door leaf open at 90 degrees. Doors on an accessible route should also provide a level threshold ($le 1/2"$ / 12.7mm with 1:2 bevel) and minimum 18" (457mm) latch-side pull clearance.
When is a double-leaf door required instead of a single-leaf door?: A single door leaf should generally not exceed **1050mm to 1100mm (3'6" to 3'8")** in width because oversized single leaves put excessive torque on hinges, cause sagging over time, and require excessive swing space. Any opening between **1200mm and 2400mm (4'0" to 8'0")** should utilize double equal leaves or a 1.5 unequal leaf (active leaf 800–900mm + passive slave leaf 350–450mm).
When are panic exit hardware (crash bars) mandatory on doors?: Per NBC 2016 Part 4 and NFPA 101 Life Safety Code, panic exit hardware (crossbar or touchpad crash bar) is mandatory on all exit doors serving **Assembly occupancies (Group D)**, **Educational spaces (Group B)**, and any room or space with an occupant load of **50 persons or more**. Panic doors must unlatch with no more than 67 N (15 lbf) of push force and must swing outward in the direction of escape travel.
How many hinges are required based on door leaf height and weight?: • **3 Hinges (Standard)**: For door leaves up to 2100mm (7'0") in height and weight up to 45 kg (standard flush and light wood doors). • **4 Hinges (Heavy Duty)**: For door leaves exceeding 2100mm (e.g. 2400mm / 8'0" doors) or heavy solid teak/fire-rated metal leaves weighing 45 kg to 100 kg. Hinges should be Grade 304 Stainless Steel Ball Bearing type (minimum 4" × 3" × 3mm or 5" × 3.5" × 3.5mm).