Step-by-Step Guide: How to Measure Your Staircase Correctly

Measuring wrong is the fastest way to lose time and money on a new stair. This step-by-step guide shows you exactly how to measure your staircase correctly, so your build kit or made-to-measure design fits first time. You’ll learn what to measure, how to allow the right tolerances, and how your numbers map to the order form.

What you’ll measure (and why it matters)

Accurate measurements ensure a safe, comfortable stair and a smooth installation. For a fixed stair you’ll typically capture:

• Height (A): finished floor-to-finished floor. Determines riser count and riser height.
• Width (C): overall stair width (outside to outside of both stringers). Drives the opening size and usability.
• Length / Outrun (B): distance along the floor from the front of the first tread to the front of the top tread. Controls steepness and headroom.
• Level and squareness: check with a spirit level. Slightly out-of-square walls can call for a scheluw (splayed) stair solution.

Because our build kits are custom cut and pre-drilled, accuracy is essential.

How to measure your staircase step by step

Follow these four steps to collect the core dimensions.

Step 1 — Measure the finished floor-to-floor height (A)

• Measure from the top of the lower finished floor to the top of the upper finished floor.
• If your upper or lower floor finish (e.g., tiles, laminate) is not installed yet, add its thickness to the measurement.
• Typical build-kit heights range from about 254 cm to 294 cm. Within this span, the riser calculation commonly uses 13 risers up to roughly 2740 mm and 14 risers above that, which keeps individual riser height comfortable.

Step 2 — Measure the overall stair width (C)

• Measure at the top of the stair opening (stairwell) from the outside of the left stringer location to the outside of the right stringer location.
• Reserve 2 cm extra clearance in the opening width beyond your chosen stair width. You can later finish this tolerance with trim.
• Straight (steek) build kits are commonly available from 70 cm up to 100 cm wide. For furniture moves and day-to-day comfort, choose the widest your space supports.

Step 3 — Measure the stair length / out-run (B)

• Measure along the floor from the nose of the first tread to the nose of the top tread.
• For straight build kits, B typically falls between 214.5 cm and 261.5 cm. A shorter B produces a steeper stair; a longer B produces a gentler stair.
• The chosen B also sets your approximate going (aantrede). With standard build kits, increasing B steps the going from about 170 mm up to about 195 mm across six B options.

Step 4 — Check level and squareness

• Use a spirit level to verify floors are level and adjacent walls are plumb.
• In existing homes, slight wall taper or skew is common. A scheluw stair can absorb minor out-of-square conditions while staying safe and walkable.

Plan the stair opening (trapgat) the right way

Opening size depends on the stair type. Use the model-specific guidance below when planning or adapting your opening.

These allowances help you frame and finish neatly while giving the stair room to sit plumb and true.

Comfort and compliance: the dimensions behind a good stair

A stair must feel natural underfoot and meet building rules.

The stair formula you can use

• The comfort guideline (stair formula) is: 2 × riser (optrede) + 1 × going (aantrede) = 570–630 mm.
• Example: If the riser is 175 mm, then 2 × 175 = 350. You’ll want a going between 220–280 mm to land within 570–630 mm, delivering a safe, comfortable cadence.

New build vs. existing homes (Bouwbesluit highlights)

• New build (typical rules):
  • Minimum stair width: 80 cm (measured outside-to-outside of stringers).
  • Maximum riser (optrede): 18.8 cm.
  • Minimum going (aantrede): 22 cm.
  • Maximum vertical height per stair flight: 4 m (add a landing if higher).
  • Minimum headroom (over the climbing line): 230 cm.
  • Guard/handrail rules apply (e.g., handrail for stairs higher than 1 m; baluster gaps ≤ 10 cm).
• Existing homes (allowances):
  • Minimum going: 13 cm.
  • Maximum riser: 22 cm.

If you’re replacing a loft ladder with a fixed stair, also consider furniture movement and traffic—sometimes a quarter- or half-turn layout makes daily use easier than a straight run.

Map your measurements to your order

When you’re ready to configure:

1. Enter Height (A): your finished floor-to-floor (commonly 254–294 cm for build kits). Riser count and riser height follow from A.
2. Enter Out-run (B): your measured floor distance (typically 214.5–261.5 cm for straight kits). This sets your going step in the kit’s B-options.
3. Enter Width (C): overall stair width (70–100 cm typical for straight kits). Frame the opening C + 2 cm.
4. Choose build details:
   • Open or closed (with stootborden).
   • Weltrede (top connecting tread): with or without.
   • Top stootbord on last tread: yes/no.
   • Anti-slip strip: milled into each tread if desired.
   • Handrails: one side, both sides, or none.
   • Pre-finishing: primed and/or lacquered, or supplied untreated.

All kits are factory-made, pre-drilled and numbered, with screws included. Treads and stringers are made from robust 40 mm material, in vuren, or with optional rubberwood treads for added durability.

Quick answers for fast readers

• How do I measure my staircase height correctly? Measure from the top of the lower finished floor to the top of the upper finished floor—include floor coverings.
• How wide should my stair opening be? Make the opening about 2 cm wider than your chosen stair width (C); finish the gap with trim.
• Where do I measure stair length (B)? Along the floor from the front edge of the first tread to the front edge of the top tread.
• What are typical straight-stair ranges? Height (A) about 254–294 cm; out-run (B) about 214.5–261.5 cm; width (C) 70–100 cm.
• Walls not square? Consider a scheluw stair to compensate for minor skew while keeping good footing.
• What headroom and widths apply in new build? Often 230 cm headroom, ≥ 80 cm width, ≤ 18.8 cm riser, ≥ 22 cm going.

Practical measuring tips

• Use a steel tape or laser, a reliable spirit level, and a notepad. Record in millimetres.
• Measure each dimension twice and have someone read back numbers to confirm.
• If floor finishes are pending, add their thickness to your measurements.
• Check for radiators, doors, or beams that could reduce headroom or interfere with the stair path.
• When space is tight, review alternative layouts: bovenkwart, onderkwart, dubbelkwart, or half-turn. If the loft is rarely used and space is extremely limited, a folding loft ladder (vlizotrap) can be a pragmatic alternative.

When to ask for expert help

Not sure your numbers are spot on? Use our Inmeetservice to have an expert measure for you. Prefer a turnkey experience? Our in-measure and installation team can handle the entire process—from confirming dimensions and drawings to a clean, professional fit.

Conclusion

Measuring your staircase correctly comes down to four things: finished height (A), clear width (C) with 2 cm tolerance, accurate length/out-run (B), and a quick level/squareness check. With those in hand, you can configure a straight, quarter-turn, double-quarter, half-turn, scheluw, or space-saving stair with confidence.

Ready to move from measurements to a beautiful, solid stair? Configure your Bouwpakket Trappen, explore Houten trap op maat, or book our Inmeetservice to get started today.