Why colour varies between batches
Manufacturing carpet is an industrial process. Even small changes in water temperature, chemical concentrations, or ambient humidity during dyeing can lead to visible colour shifts between batches. If you order half your runner from one lot and the other half from another, the difference can be subtle but glaringly obvious once laid down on the stairs.
How to ensure a match
When ordering, clearly specify that you need the entire length to be from a single dye lot. Most reputable suppliers will flag this for you, but it is always better to be proactive. If you are buying a large quantity, confirm that the supplier has sufficient stock in a single batch before you place your order.
How much runner do I need?
For a 13-step flight: 10 in tread + 7.5 in riser + 0.75 in wrap = 18.25 in per step. Total 237.25 in. Adding 24 in for finishing = 261.25 in (21.77 ft). Including a 10% safety margin for wastage, you should order at least 24 ft. Metric: 25 cm tread + 19 cm riser + 1.9 cm wrap = 45.9 cm per step. Total 596.7 cm, plus 60 cm = 656.7 cm. With 10% safety, aim for 7.3 m.
| Step | Action |
|---|---|
| Confirm | Check stock lot numbers |
| Specify | Request single dye lot in writing |
| Verify | Check colour across the whole length before fitting |
| Store | Keep sample to verify match |
Know your numbers in 30 seconds
Enter your step count, tread depth and riser height — the stair runner calculator gives you the exact length to order, in metres and feet, with waste included.
Open the stair runner calculatorWhen a match is impossible
If you have an exceptionally long flight that exceeds the length of a single roll, discuss with your fitter the best place to make a seam—usually at a landing or where a stair rod can hide the join.
- Always order all your required length at once.
- Check the labels on the roll for dye lot numbers.
- If the supplier cannot provide a single lot, ask for photos of the two rolls side-by-side.
- Notify the fitter immediately if you suspect a colour variation.
Managing expectations
Even within a single dye lot, natural fibres like wool can have subtle colour variations—this is part of the charm of the material. Synthetic runners should be perfectly uniform. If your runner shows a clear, hard-line colour difference, it is likely a manufacturing fault, not a natural variation.
Whatever you decide, get the numbers first: the stair runner calculator doubles as a stair runner length calculator, adding nosing wrap, landings, winders, pattern repeat and waste so you order the right length the first time.
Still deciding on material, width or pattern? Our hub on stair runners compares weaves, widths, backings and fitting styles side by side, then hands the numbers straight to the calculator.
Frequently asked questions
What is a dye lot?
It is the batch number of the carpet production. It ensures that all the carpet in that batch was dyed in the same process, guaranteeing a uniform colour.
Can I order more later?
It is highly risky. Even if the product code is the same, the dye lot will almost certainly have changed, and the colours won't match.
Is this only for patterned carpet?
No, solid-coloured runners are often even more sensitive to dye lot variations because there is no pattern to hide slight colour shifts.
What should I do if the batches don't match?
Do not install it. Contact the supplier immediately and provide evidence of the mismatch.
Do synthetic fibres have dye lots?
Yes, all dyed fibres have dye lots. Even solution-dyed synthetics can have subtle variations between batches.
Can my fitter hide a mismatch?
Unlikely. If the colour difference is significant, no amount of clever fitting will disguise it.
Why is wool more variable?
Natural wool takes dye differently depending on its origin and the season, which can cause minor variations that don't exist with synthetic fibres.
How do I check the dye lot?
It is usually printed on the end of the roll label. Always record this number from your delivered product.
Know your numbers in 30 seconds
Enter your step count, tread depth and riser height — the stair runner calculator gives you the exact length to order, in metres and feet, with waste included.
Calculate your length with the stair runner calculatorEvery guide is written from hands-on measuring and fitting experience, checked against the calculator’s own maths, and re-reviewed whenever prices or methods change. Read our editorial standards.