Sizing & Absorbency
Sizing & Absorbency Guide
Finding your perfect fit makes all the difference for comfort, confidence, and leak protection. Because our products are personal hygiene items and cannot be returned once opened, we want to make sure you get it right first time. This guide covers everything you need — from how to measure yourself to understanding absorbency capacity.
If you still have questions after reading, please get in touch — we're happy to help.
Step 1: How to Measure Yourself
Getting an accurate waist measurement is the most important step. Here's how to do it correctly:
- Stand upright in a relaxed, natural position.
- Use a flexible fabric measuring tape — not a rigid ruler or metal tape.
- Measure around your natural waist — roughly at the level of your belly button, the narrowest part of your torso.
- Keep the tape snug but not tight — you should be able to slip one finger underneath.
- Measure over light undergarments if you plan to wear the diaper over them, or directly on skin for the most accurate result.
- Note your measurement in both cm and inches — our charts show both.
Tip: If you're between two sizes, scroll down to our "Choosing Between Sizes" section for guidance specific to tape-on and pull-up styles.
CustomZ Tape-On Diaper Size Chart
Our tape-on diapers are our most popular style and offer the highest absorbency. The adjustable tapes allow for a more customisable fit across a wide waist range.
| Size | Waist (cm) | Waist (inches) | Capacity |
|---|---|---|---|
| Medium | 70–120 cm | 27.6–47.2" | 4,450 ml |
| Large | 100–150 cm | 39.4–59.1" | 5,150 ml |
| Extra Large | 110–165 cm | 43.3–65.0" | 5,150 ml |
Note: Medium and Large have overlapping waist ranges. If you fall in the overlap (100–120 cm), see "Choosing Between Sizes" below.
CustomZ Pull-Up Size Chart
Pull-ups have a different fit and sizing to our tape-on styles. Important: Pull-ups run small — we recommend sizing up if you are between sizes or near the top of a size range.
| Size | Waist (cm) | Waist (inches) | Capacity |
|---|---|---|---|
| Small/Medium | 75–100 cm | 29.5–39.4" | 1,700–2,200 ml |
| Large | 100–130 cm | 39.4–51.2" | 1,700–2,200 ml |
Capacity varies slightly by style (plastic-backed vs cloth-backed). Check individual product pages for exact figures.
Understanding Absorbency & Capacity
All our products list their capacity in millilitres (ml). Here's what that means in practice:
- 1,700–2,200 ml — Light to moderate use. Great for daytime wear or shorter periods. Roughly 3–4 average voids.
- 4,450 ml — High absorbency. Extended daytime or moderate overnight use. Roughly 7–9 average voids.
- 5,150 ml — Maximum absorbency. Overnight or all-day wear without changes. Roughly 9–11 average voids.
Capacity is a lab measurement under controlled conditions. Real-world performance depends on fit, body position, and activity level — a well-fitted diaper will always perform better than one that is too loose or too tight.
Plastic-backed vs cloth-backed: Plastic-backed styles hold capacity closer to their rated maximum. Cloth-backed styles are more breathable for longer wear but may feel saturated slightly sooner.
Choosing Between Sizes
Tape-On Diapers
- Between Medium and Large (100–120 cm): size down to Medium — the adjustable tapes let you fine-tune the fit.
- Between Large and Extra Large (110–150 cm): if you carry weight around the hips or thighs, Extra Large may be more comfortable.
- Prefer a looser fit? Size up.
Pull-Ups
- Pull-ups run small — size up if you're at the top of a range or between sizes.
- A pull-up that's too tight will be uncomfortable and may leak at the leg openings.
Fit Tips for Comfort & Leak Protection
Signs of a Good Fit
- Waistband sits flat and snug without digging in
- Leg cuffs lie flat against the skin with no gaps
- You can move freely without the diaper shifting
- Tapes fasten symmetrically on both sides
Signs It's Too Tight
- Red marks or indentations on skin after removal
- Discomfort or restriction when sitting or moving
- Tapes pulling or not reaching the landing zone
Signs It's Too Loose
- Gaps at the leg openings or waist
- Diaper sagging or shifting during wear
- Leaking at the sides or legs
Tape-On Fitting Tips
- Fasten the bottom tapes first, angling them slightly upward
- Then fasten the top tapes horizontally for a secure waist seal
- Ensure front and back panels are level when fastened
- Run a finger along the leg cuffs to make sure they're not tucked inward
Brand-Specific Sizing (GoodNites, Pampers & Others)
For full packs and samples from brands like GoodNites and Pampers, sizing is set by the manufacturer and may differ from CustomZ sizing. We recommend:
- Referring to the manufacturer's own size chart for the most accurate guidance
- Noting that US and UK sizing can differ — always check measurement ranges rather than size labels alone
- Using age/weight guidelines as a reference only — waist measurement is more reliable for adults
Frequently Asked Questions
What size should I order for my waist measurement?
Use the size charts above. If you're between sizes, size down for tape-on styles and size up for pull-ups.
Do pull-ups fit the same as tape-on diapers?
No — pull-ups run smaller. If you normally wear a Medium tape-on, you may need a Large pull-up. Always check the pull-up chart separately.
What if I'm between sizes?
Size down for tape-on diapers, size up for pull-ups.
What's the difference in capacity between Large and Extra Large tape-on diapers?
Both hold 5,150 ml — the difference is the waist range and fit, not absorbency. Choose based on your measurements.
What does capacity mean in real terms?
Capacity is measured in ml under lab conditions. Roughly: 4,450 ml suits extended daytime or moderate overnight use; 5,150 ml is ideal for overnight or all-day wear. See "Understanding Absorbency" above for the full breakdown.
Still Not Sure? Get in Touch
We know getting the right fit matters — especially with our strict no-returns policy on opened hygiene products. If you've read this guide and still have questions, please contact us. We're here to help you find your perfect fit.