Door Rough Opening Calculator
Enter the finished door leaf size, your frame section thickness and a packing gap — and get the frame outer size, the rough / structural opening to leave in the wall, and a lintel note. Indicative India 2026 — measure twice on site.
Your door & frame
Typical seasoned-hardwood frame. Frame outer = leaf + section both jambs (width) + one section at the head (height); rough opening adds the packing gap each side (and at the head if set). The jamb feet sit on finished floor — no gap there. Indicative India 2026 — confirm with your carpenter.
Rough / structural opening to leave in masonry
0 mm×0 mm
Width × Height · 41 × 86 in
Leaf
900×2,100
finished door
Frame outer
1,024×2,162
chowkhat
Rough opening
1,044×2,172
masonry
Width & Height grow leaf → frame → opening.
Lintel note
Set an RCC lintel above the opening with at least 150 mm bearing each side — run it about 1,344 mm long (opening 1,044 mm + bearings). Provide a DPC course and anti-termite treatment at the frame base.
Get the opening right before the wall goes up
DesignAI checks your rough opening, lintel bearing and frame detail against your wall type and door schedule — so the chowkhat fits first time, plumb and square.
How this works & site notes
- Frame outer = finished leaf + frame section on both jambs (width) and one section at the head (height); the rough opening adds your packing gap each side and at the head. The jamb feet rest on the finished floor, so no gap or section is added there.
- The packing gap is what you grout / foam after the frame is set plumb, level and square — that is non-negotiable; frame plumb tolerance is ~1–2 mm over the height.
- Provide a DPC course and anti-termite treatment at the frame base, standard practice for timber chowkhats in India. Hang the leaf with ~3 mm head & stile gaps and a 6–12 mm bottom undercut; an accessible threshold should be ≤12 mm, bevelled if >6 mm.
- Lintel bearing of ~150 mm each side is a common rule of thumb — your structural engineer sets the actual lintel for the span and load.
Figures are indicative for India 2026 in millimetres — confirm with your carpenter / fitter on site and measure twice before cutting masonry. This is a guidance tool, not a substitute for a skilled carpenter or site engineer. (No cost is computed here; where doors and fitting are priced elsewhere, 18% GST applies.)
Related Guides — Deep-dive reading
Door Rough Opening in India: Set Out the Opening (India 2026)
How to size a door's structural opening — finished leaf size, frame outer size, the 10-12mm gap each side and the lintel above.
Home Doors & EntrancesDoor Lintel Requirements: RCC Header Sizing (India 2026)
Why every door opening needs a lintel — the RCC/precast header that carries the wall load, minimum bearing, depth rules of thumb, and lintel-vs-beam decisions.
Home Doors & EntrancesDoor Opening Preparation Before Fitting (India 2026)
How to prep a door opening before the chowkhat goes in — checking size, plumb and square, confirming the lintel, laying DPC and marking holdfasts.
Home Doors & EntrancesRelated Tools — You may also find these useful
Access Control Cost Estimator
Estimate per-door and whole-building access-control cost in India, with the full component breakdown and GST.
Cost EstimatorAccess Control ROI Calculator
Compare automated access control against guard and manual costs to find the saving and payback.
ROI CalculatorAccess Control System Designer
Design a door access-control system for your building and get the component BOM, topology and indicative cost.
System Designer