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15 May 2026

Measuring in Millimeters: Avoiding Common Dimension Mistakes Before Ordering Your Stair Kit

Ordering a stair you’ll love starts with one deceptively simple step: measuring in millimeters. Tiny unit mix-ups can lead to big on-site headaches—tight fits, gaps, or last‑minute adjustments you didn’t plan for. This guide shows you exactly what to measure, where errors creep in, and how to submit rock‑solid dimensions so your ready‑to‑assemble kit fits first time.

You’ll learn the critical measurements every stair project needs, the most common mistakes (and how to avoid them), and when to lean on our self‑measurement guide or professional Inmeetservice for peace of mind.

Why millimeters matter for a perfect‑fit stair kit

A wooden stair kit is custom‑made around your sizes. Components—stringers, treads, and risers—are supplied pre‑cut to your dimensions, so accuracy upfront pays off on installation day. Pine (spruce) kits are pre‑drilled to speed assembly, and every kit includes the fixings and a step‑by‑step manual so you can install it yourself or hand it to your contractor.

Accurate, millimeter‑precise measurements also help ensure your design aligns with Dutch (and Belgian) building regulations for proportion, headroom, and usability. Our staircases are engineered to meet the applicable standards, and our team can review your specifics to help ensure the installed result complies.

If you prefer expert help, book the professional Inmeetservice. Prefer DIY? Use the step‑by‑step “how to measure” guidance and submit your sizes through the online Stair Configurator.

The core dimensions you must capture (in millimeters)

Measure all sizes in millimeters (mm) and record them clearly.

Dimension What it means
Floor‑to‑floor height Vertical distance from finished lower floor to finished upper floor
Stairwell opening (length × width) The clear size of the floor opening that the stair passes through
Headroom Vertical clearance along the stair’s walking line under ceilings/beams
Available run/footprint The horizontal space the stair can occupy on the lower floor, including turns
Intended stair width The clear width you want for the stair itself
Landings/turns Any upper/lower quarter‑turns, half‑turns, or landings that affect layout
Finish thicknesses Floor coverings, underlays, and ceiling finishes that change final sizes

Tip: Note obstacles (doors, radiators, beams, services) and wall conditions (plumb/level). Add photos to your dimension sheet for clarity.

10 common mistakes when measuring in millimeters—and how to avoid them

1) Mixing units (cm/inch/mm)

2) Rounding or estimating

3) Measuring floor‑to‑ceiling instead of floor‑to‑floor

4) Forgetting finish thickness

5) Assuming openings are square and walls are plumb

6) Ignoring headroom and obstructions

7) Overlooking trims, skirting, or services

8) Measuring to raw structure when finishes are coming later

9) Sending unclear sketches

10) Skipping a regulation sense‑check

Step‑by‑step measuring checklist (ready to print)

  1. Set your tape/laser and notes to millimeters only.
  2. Record floor‑to‑floor height (finished lower to finished upper floor).
  3. Measure stairwell opening length and width at least twice (and compare). Check diagonals.
  4. Map headroom along the intended walking line; note any beams/soffits.
  5. Mark the available footprint on the lower floor, including turns or landings.
  6. Choose your intended stair width (consider walls, trims, and balustrades).
  7. List all finish thicknesses (flooring, underlay, plaster/ceiling) that affect sizes.
  8. Photograph the opening, surrounding walls, and any obstructions.
  9. Create a simple plan and side elevation with labeled mm dimensions.
  10. Enter sizes in the Stair Configurator or book the Inmeetservice for a professional site measure.

Tools and techniques for accurate millimeter measurements

Submitting your dimensions and planning your order

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Quick answers: common measurement questions

What should I measure first for a stair kit?

Start with finished floor‑to‑finished floor height in millimeters, then the stairwell opening (length × width), headroom along the walking line, available footprint, and intended stair width.

Should I measure in millimeters or centimeters?

Measure in millimeters only. It eliminates rounding errors and aligns with our configuration and production process.

Can you measure for me?

Yes. Our Inmeetservice sends a specialist to measure your space accurately. You can also arrange the combined Inmeet‑ & Montageservice for measurement and installation.

Do kits arrive pre‑cut and ready to assemble?

Yes. Stringers, treads, and risers are pre‑cut to your provided dimensions and supplied with all required fixings and a step‑by‑step assembly manual. Pine (spruce) kits are pre‑drilled to simplify alignment.

Do your staircases meet building regulations?

Yes. Our staircases are designed and manufactured to meet applicable Dutch (and Belgian) building regulations for dimensions, safety, and usability.

Can I install the staircase myself?

Yes. Our ready‑to‑assemble kits are designed for self‑installation or fitting by your contractor.

Practical takeaways

Conclusion: measure with confidence, order with certainty

Precise measuring in millimeters is the fastest path to a stair kit that fits perfectly and installs smoothly. Whether you follow the self‑measurement guide or prefer our Inmeetservice, you’ll set your project up for success—from design and compliance to delivery and assembly.

Ready to move forward?

Design it right, measure in millimeters, and enjoy a staircase that looks great and performs beautifully.