Size Chart
Finding your size takes two minutes and a soft tape measure. Measure your waist and hips, match them to the charts below, and if you fall between two sizes in period panties, size down — the absorbent gusset has to sit flush against the body to work. Every measurement here is given in both inches and centimetres.
How to measure yourself
Use a soft tape measure over bare skin or thin clothing. Keep the tape level and snug, but never pulled tight — you should be able to slip a finger underneath.
- Waist — measure around the narrowest part of your natural waist, usually just above the belly button.
- Hips — stand with your feet together and measure around the fullest part of your hips and bottom.
- Under bust (for bras) — measure directly under the bust, around the rib cage, with the tape firm.
- Over bust (for bras) — measure around the fullest part of the bust, keeping the tape loose and level.
Period panties & underwear size chart
Our period panties and everyday underwear follow standard international sizing. Match your hip measurement first — it is the most reliable guide for a leak-proof fit.
| Size | UK | Waist (in) | Waist (cm) | Hip (in) | Hip (cm) |
|---|---|---|---|---|---|
| S | UK 8 | 26–28 | 66–71 | 34–36 | 86–91 |
| M | UK 10 | 28–30 | 71–76 | 36–38 | 91–97 |
| L | UK 12 | 30–32 | 76–81 | 38–40 | 97–102 |
| XL | UK 14 | 32–34 | 81–86 | 40–42 | 102–107 |
| 2XL | UK 16 | 34–36 | 86–91 | 42–44 | 107–112 |
| 3XL | UK 18 | 36–39 | 91–99 | 44–47 | 112–119 |
Choosing absorbency (just as important as size)
A perfectly sized pair will still feel wrong if the absorbency does not match your flow. Absorbency is measured in millilitres and compared here to regular disposable pads.
| Level | Holds | Equivalent to | Best for |
|---|---|---|---|
| Light | 5–10 ml | 1–2 pads | Spotting, first and last days, discharge, backup |
| Moderate | 10–20 ml | 2–3 pads | Average flow, work and school days |
| Heavy | 20–35 ml | 3–5 pads | Heaviest days, long days out |
| Overnight | 35–50 ml | 5+ pads | Sleeping, very heavy flow, postpartum |
If you are unsure, choose one level higher than you think you need. Most first-time buyers start with one moderate pair for daytime and one overnight pair, then build a rotation of 3–5 pairs. Our complete period panties guide explains how the layers work.
Bra & lingerie size chart
Bra sizing combines a band (from your under-bust measurement) and a cup (the difference between your over-bust and under-bust).
| Under bust (in) | Band size | Cup B — over bust | Cup C — over bust | Cup D — over bust |
|---|---|---|---|---|
| 27–28 | 32 | 33–34 | 34–35 | 35–36 |
| 29–30 | 34 | 35–36 | 36–37 | 37–38 |
| 31–32 | 36 | 37–38 | 38–39 | 39–40 |
| 33–34 | 38 | 39–40 | 40–41 | 41–42 |
Activewear, swimwear & shapewear
Sports bras, leggings and period swimwear use the same size letters, matched to bust, waist and hip together.
| Size | Bust (in) | Waist (in) | Hip (in) |
|---|---|---|---|
| S | 32–34 | 26–28 | 34–36 |
| M | 34–36 | 28–30 | 36–38 |
| L | 36–38 | 30–32 | 38–40 |
| XL | 38–40 | 32–34 | 40–42 |
For period swimwear, size for your hips and choose a snug fit — fabric relaxes slightly in water.
Fit troubleshooting
| What you notice | What it usually means | What to do |
|---|---|---|
| Leaks at the sides | The gusset is not sitting flush — the pair is too loose | Size down, or choose a boyshort cut for wider coverage |
| Waistband digs in | Too small in the waist for your hip size | Size up, or choose a high-waist style that distributes pressure |
| Feels wet quickly | Absorbency is too light for your flow, not a size problem | Move up one absorbency level |
| Rides up at the back | Hip measurement is at the upper end of the range | Size up, or pick a full-brief cut |
Still not sure?
Send us your waist and hip measurements on WhatsApp and we will recommend a size before you order. If it arrives and the fit is not right, unworn items with tags can be exchanged — see our returns and exchanges policy.
WhatsApp: +94 74 101 2016 · Email: periodpanties.lk@gmail.com
Frequently asked questions
What size period panties should I buy?
Match your hip measurement to the chart above — hips are more reliable than waist for period underwear. If you fall between two sizes, size down so the absorbent gusset sits flush against the body.
Should I size up or down in period panties?
Size down. A loose fit is the most common cause of side leaks, because the absorbent layer needs contact with the body to catch flow. For regular lingerie and loungewear, size up for a relaxed fit.
How do I measure my hips correctly?
Stand with your feet together and run a soft tape measure around the fullest part of your hips and bottom, keeping it level all the way round. Do not pull it tight — you should be able to slide a finger under the tape.
Do period panties shrink after washing?
Not if you wash them correctly. Rinse in cold water, wash on a gentle cycle with normal detergent, and air dry. Hot water and tumble drying can shrink the outer fabric and damage the absorbent core.
What is the difference between UK sizes and S, M, L?
They map directly: S is UK 8, M is UK 10, L is UK 12, XL is UK 14, 2XL is UK 16 and 3XL is UK 18. Both are shown in the chart above so you can order with confidence either way.
Which absorbency should I choose?
Light (5–10 ml) for spotting, moderate (10–20 ml) for average days, heavy (20–35 ml) for your heaviest days, and overnight (35–50 ml) for sleeping. When in doubt, go one level higher.
Can I exchange if the size is wrong?
Yes. Unworn, unwashed items with tags attached can be exchanged within 7 days of delivery. For hygiene reasons we cannot accept returns on worn intimate items unless they are faulty.