Size Guide & Fit
Last updated: 21 May 2026
1. Introduction
This Size Guide helps you choose the right size when ordering shirts from ROSTTYA. It covers UK / EU / US size conversions, body measurements in centimetres, instructions on how to measure yourself accurately, and our approach to model height disclosure and per-product garment measurements.
If you are unsure about sizing after reading this guide, email hello@rosttya.com with your measurements (chest, waist, hip) and we will recommend a size for the specific shirt you are considering. We typically reply within 1 working day.
At launch ROSTTYA offers UK sizes 6 through 16 across all shirts. The range will be reviewed in future seasons.
2. Size Conversion Table (UK / EU / US)
Our shirts are designed to fit standard UK body measurements as set out below. The table reflects body measurements (the size of the wearer), not garment measurements (the size of the shirt itself, which has additional ease for movement). Garment measurements for each specific shirt are listed on its own product page.
| UK | EU | US | Bust (cm) | Waist (cm) | Hip (cm) |
|---|---|---|---|---|---|
| UK 6 | EU 34 | US 2 | 80 | 62 | 86 |
| UK 8 | EU 36 | US 4 | 84 | 66 | 90 |
| UK 10 | EU 38 | US 6 | 88 | 70 | 94 |
| UK 12 | EU 40 | US 8 | 92 | 74 | 98 |
| UK 14 | EU 42 | US 10 | 96 | 78 | 102 |
| UK 16 | EU 44 | US 12 | 100 | 82 | 106 |
The body measurements above are based on UK standard sizing (BSI EN 13402-3). Brand size labelling varies across the industry; if you typically wear a different size in another brand, the body measurements below are the most reliable guide.
3. How to Measure Yourself
For the most accurate fit, measure yourself in light underwear or a thin top using a soft tape measure. Stand naturally with arms relaxed. If a friend can help, results are usually more accurate than measuring yourself.
Bust
Measure horizontally around the fullest part of your bust, with the tape going under the arms and across the shoulder blades. Keep the tape snug but not tight. Do not hold your breath in or push your chest out.
Waist
Measure horizontally around your natural waistline — the narrowest part of your torso, typically about 2 cm above your navel. Keep the tape level and parallel to the floor. Do not pull the tape in tightly.
Hip
Measure horizontally around the fullest part of your hips and seat, typically about 20 cm below your natural waistline. Keep your feet together and the tape parallel to the floor.
Shoulder (optional, useful for tailored shirts)
Measure across the back from the outside edge of one shoulder bone to the outside edge of the other.
Sleeve length (optional)
From the shoulder seam down the outside of your relaxed arm to the wrist bone.
4. Garment Measurements (Per Product)
Body measurements alone do not tell you exactly how a specific shirt will fit, because each style has different ease, cut and design intent. For example, an oversized shirt in UK 10 has wider garment measurements than a tailored shirt in UK 10, even though both are designed for the same body measurements.
Every product page on the Website lists the following garment measurements, in centimetres, for each available size:
- Chest width (flat measurement, doubled gives full bust)
- Shoulder width
- Sleeve length (from shoulder seam to cuff)
- Body length (from highest point of shoulder to hem)
- Cuff opening width
If you have a favourite shirt at home, lay it flat and measure these dimensions. Compare to the garment measurements on our product page to find the size that most closely matches.
5. Model Height Disclosure
Every product page on the Website discloses the height of the model wearing the shirt in the photographs, and the size the model is wearing. For example: “Our model is 173 cm and is wearing UK size 10.” This helps you visualise how the shirt will sit on a body close to your own height.
Where multiple models appear in the same product’s photographs, the model height and size worn is given for each model individually.
6. Fit Types
Different shirt styles are designed with different fits. Each product page tags the shirt with one of the following fit categories so you know what to expect:
- Tailored fit: closer to the body through the bust and waist, with darts or shaping. Choose your usual size for a fitted look, or size up for a more relaxed line
- Regular fit: straight cut with moderate ease. Choose your usual size
- Relaxed fit: generous through the body with extra ease at the bust and hem. Choose your usual size — sizing down may compromise sleeve length
- Oversized fit: intentionally loose and roomy. Sizes are unisex-leaning. Most customers wear their usual UK size; some prefer to size down for a slightly more structured look
Between Sizes?
If your body measurements fall between two sizes:
- For tailored fit shirts: consider sizing up for comfort, especially through the bust
- For regular fit shirts: choose the size that matches your bust measurement
- For relaxed and oversized fit shirts: choose the smaller of the two sizes — the extra ease will accommodate the larger measurement
7. Exchanges for a Different Size
If you order a shirt and find the size is not right, you can return it under our 30-day commercial return window and exchange it for the same shirt in a different size. As a goodwill gesture to support correct sizing, we refund your return shipping cost on size exchanges (this is set out in our Returns & Refunds Policy clause 4).
For step-by-step return instructions, see the Returns & Refunds Policy or email hello@rosttya.com.
8. Care for Lasting Fit
Garment fit can change with washing. To preserve the original fit of your shirt:
- Follow the care label inside each garment
- Cotton and linen shirts: wash cool (30°C maximum) on a gentle cycle, reshape while damp, and air dry. Tumble drying can cause shrinkage and altered fit
- Iron while slightly damp on the reverse side, at the temperature setting indicated on the care label
- Avoid bleach unless explicitly recommended on the care label
9. Questions?
If after reading this guide you are still unsure which size to order, please email hello@rosttya.com with:
- The specific shirt you are considering (product name or URL)
- Your body measurements (bust, waist, hip in cm)
- Your usual UK size in another brand, if helpful
We will reply within 1 working day with a personalised size recommendation.
10. Contact
ROSTTYA LTD
5c Forster Road
London, N17 6QD
United Kingdom
Email: hello@rosttya.com
Phone: +44 7972107661
ROSTTYA LTD is a company registered in England and Wales, Company Number 16632288. The sole director is Rostislav Dimitrov Rusinov.
