Last updated: 2025-12-23
Stop the leaks and mould. A 100% watertight shower starts with a perfect measurement. Follow this quick 2-minute guide to find your match.
SIMBA Tip: 90% of leaks are due to wrong sizing. Measure twice, buy once!
Preparation: Tools You’ll Need
Before you start, gather these basic tools to ensure a precise, professional measurement:
- 📏 Tape Measure (Metric/mm)
- 📝 Pen & Paper
- 🔦 Torch
- ♻️ Old Seal (For reference)
How to Measure for a Shower Door Bottom Seal
Measuring for a Bottom Shower Seal requires three numbers:
A. Glass Thickness:
Usually 4mm, 6mm, 8mm, or 10mm. Why it matters: Pick the wrong one, and your seal will fall off or won’t go on.
The SIMBA Standard: Our seals are engineered to provide a secure grip with over 50N of friction force. This ensures the strip stays firmly in place without sliding, even on heavy 10mm glass doors.
Check our shower screen seal grip the glass test:
Expert "Coin Trick" for Accuracy
Pro Tip: Use the "Coin Trick"—clamp two coins on the glass and measure the gap.
B. Gap Size:
Vertical distance from glass bottom to the tray.
- How to measure: Close your shower door and measure the clearance at both ends of the door (sometimes floors aren't perfectly level!).
- Rule: The seal "Fin" must touch or slightly overlap the tray to block water.
The SIMBA Standard: 50N+ grip force—no slipping, even on heavy 10mm glass.
3. Measure Your Length of Shower Glass
SIMBA provides two standard lengths to fit 98% of UK shower doors. You simply trim them to your exact size during installation.
- Bottom Seals: Supplied at a generous 950mm.
- Vertical & Side Seals: Supplied at a full 2000mm.
Fit Tip: We provide extra length because manual measurements often have minor errors. Trim for a flush, professional finish using our How to Cut Guide.
4. Curved Glass: Arc vs. Chord
Measuring a Curved Shower Seal is simple once you know these two points:
1. Thickness & Gap Size
The method for measuring Glass Thickness and Gap Size for a curved screen is exactly the same as for a straight seal. (See Step 1 & 2 above).
2. Understanding the Curve: The Arc vs. The Chord
Outer Arc: Measure along the outside curved edge of the glass.
The Chord: Measure the straight-line distance between the two ends.
Our Curved Shower Seals (pre-curved for standard UK 800mm radius screens) will fit perfectly. No Fit? 100% Full Refund.
How to Measure Vertical & Magnetic Shower Seals
Vertical seals stop water escaping from the sides of your door. Follow these two checks:
Step 1: The Side Gap (Clearance)
Standard Doors: Measure the gap between the glass and the wall at its widest point.
Sliding Doors: Measure the Overlap Gap (the clearance between the two glass panels).
Step 2: Vertical Length
SIMBA Standard: We provide all our Vertical & Magnetic Seals at a professional length of 2000mm, allowing you to trim for a bespoke, flush fit.
Pro "Cheat Codes" from UK Fitters
Don't let uneven walls or tight gaps ruin your installation. Use these professional tricks:
- The Coin Trick: If a gap is too tight for a tape measure, slide a coin (or a stack of coins) into it. Measure the coins afterward to get your exact gap or glass thickness.
- The "Widest Point" Rule: Many UK bathrooms have slightly "wonky" walls. Always measure the widest part of any gap. It is much easier to trim a long seal fin than to fix a leak caused by one that's too short.
Still Not Sure? Let Us Decide for You
Don’t let measurement stress stop you. Use our "Expert Match" service to get it right the first time:
2. ✍️ Send Your Guess: Include rough measurements.
3. 🔗 Get Your Link: Direct match sent within 24 hours.
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