01
Calibrate
Place a credit card (or local coin) on screen and match it to the on-screen outline. We save the scale factor so your screen is accurate forever after.
Free virtual ring sizer · works on screen + phone
Ring Size App.
Ring Size App.
Actual ring size on screen.
The free virtual ring sizer with an actual ring size chart on screen and phone. A complete ring size calculator, ring measuring app and ring size finder in one. Place a ring you already own on the display, drag until the inner edges match, and get your exact US, UK, EU and JP ring size instantly. No download, no sign-up.
Calibrated to your screen
US · UK · EU · JP sizes
Works on phone, tablet, desktop
Nothing is uploaded — fully private
1Start
2Calibrate
3Measure
4Result
How it works
Three quick steps to your exact ring size. Average time: under 2 minutes.
-
1
Calibrate Hold a credit card on the screen and match the on-screen outline. Done once, saved forever.
-
2
Measure Place a ring you own on the screen and match the inner edge — or measure your finger with a paper strip.
-
3
Get your size See your size in US, UK, EU and JP — plus diameter and circumference in millimetres.
Already know your size? Jump to the full conversion chart
Calibrate your screen
So the on-screen ring matches real-world millimetres exactly.
Place a credit or debit card flat against the screen and adjust the slider until the shape below matches its size exactly.
↔ Scroll the outline if it extends past the screen — the size shown is physically accurate.
Tips for accurate calibration
Ensure your browser zoom is 100%.
Place the object directly on the screen (no case or sleeve).
Use good lighting and look straight on, not at an angle.
Re-calibrate if you switch devices.
Place the object directly on the screen (no case or sleeve).
Use good lighting and look straight on, not at an angle.
Re-calibrate if you switch devices.
Place your ring on the screen
Drag the slider until the gold circle matches the inner edge of your ring. Re-calibrate screen
Use ← → arrow keys for fine adjustment
Measure your finger
1 — Wrap a thin strip of paper around your finger. 2 — Mark where the end meets. 3 — Hold the strip flat against the ruler below and drag the marker to the mark. Re-calibrate screen
Drag the marker — or tap anywhere on the ruler
Circumference 57.0 mm
· US Size 8
±0.05 mm
Calibrated precisionUS · UK · EU · JP
Size conversions100%
On-device · nothing uploaded$0
No install · runs in your browser
How it works
The most accurate online ring sizer, in three steps.
Unlike printable charts or generic image-based sizers, RingSize.app calibrates to your screen so the displayed ring matches real millimetres — the same way a jeweller would size you in store.
02
Measure
Place an existing ring on screen and adjust until the inner edges line up — or measure your finger circumference with a paper strip on our calibrated ruler.
03
Convert
Read your exact size in US, UK, EU and Japanese standards, with diameter and circumference in millimetres for jewellers worldwide.
International conversion
A quick look at the ring size chart.
Diameter and circumference in millimetres, mapped to US, UK and European standards. Need every half-size and Japanese conversions? Open the full chart →
| US | UK | EU | Diameter (mm) | Circumference (mm) |
|---|---|---|---|---|
| 5 | J | 49 | 15.7 | 49.3 |
| 6 | L | 51.5 | 16.5 | 51.9 |
| 7 | N | 54 | 17.3 | 54.4 |
| 8 | P | 57 | 18.1 | 57.0 |
| 9 | R | 59 | 19.0 | 59.5 |
| 10 | T | 62 | 19.8 | 62.1 |
| 11 | V | 64 | 20.6 | 64.6 |
| 12 | X | 66.5 | 21.4 | 67.2 |
FAQ
Common questions about our free ring size app.
How accurate is the free ring size app with actual ring size chart on screen?
Our free ring size app with actual ring size chart on screen is highly accurate when properly calibrated. By using physical objects like coins or credit cards for screen calibration, you'll see the actual ring size on screen with accuracy comparable to professional jeweller measurements — typically within ±0.05 mm of a sized mandrel.
What objects can I use for calibration?
You can use local coins or a standard ID-1 credit/debit card (85.60 × 53.98 mm): US Quarter (24.26 mm), 1 Yuan (25.00 mm), 1 Euro (23.25 mm), Canadian 25¢ (23.88 mm), ₹5 Rupee (23.00 mm), $1 AUD (25.00 mm) or $1 SGD (24.66 mm). The app automatically detects your region and suggests the most universal option.
Does the free ring sizer app work on mobile phones?
Yes — our free ring sizer app works on every modern smartphone, tablet and desktop browser. The actual ring size chart on screen adapts to any device and re-uses your saved calibration so you only need to set it up once per screen.
Is the ring size app really free?
Yes — completely free. There's no registration, no download, no paywall, and no ads on the sizer itself. We may earn a small commission if you choose to buy a ring through our partner links after measuring.
Can I measure different fingers with this tool?
Absolutely. The tool measures circumference — which is the universal language of ring size — so it works for any finger. For eternity bands or unusually wide settings, we recommend rounding up by ½ size.
What's the best time of day to measure ring size?
Fingers swell slightly through the day and in warm weather. For the most reliable fit, measure in the late afternoon or evening at a normal room temperature — that's how you'll wear the ring most of the time.
How is this different from a virtual ring sizer or digital ring sizer image?
A printed or static "virtual ring sizer" image only works if the printer or screen reproduces it at exactly 100% scale — which it rarely does. RingSize.app is a true digital ring sizer because it calibrates to your specific screen using a credit card or coin, so the actual ring size on screen matches real millimetres on any device.
Can I use this as an actual ring size chart on my phone?
Yes — the actual ring size chart on phone view is fully supported. Calibrate using a credit card pressed against your phone screen, then place your ring directly on the display. You can also tap "Send to phone" on desktop to get a QR code that opens the sizer on your mobile.
Is there an actual ring size chart for women's and men's rings?
Ring sizes are universal — there is no separate scale for women's vs men's rings. The same US/UK/EU sizing applies to both. Women's ring sizes most commonly fall between US 5 and 7; men's between US 9 and 11. Our ring size calculator covers US 3 through 13 (UK F through Z, EU 44 – 69) for everyone.
Does the actual ring size chart on screen work in the UK?
Yes. Calibrate with any standard ID-1 credit/debit card (85.60 × 53.98 mm — same dimensions worldwide) and you'll see the actual ring size chart on screen UK users expect. The result panel converts your size to UK letter sizes (F – Z), EU and JP standards automatically.
Can I measure ring size on phone for free?
Yes — measuring ring size on phone is free with no installation. Open ringsize.app in your mobile browser, calibrate with a credit card, and place a ring on the screen. There is no app to download and nothing leaves your device.
Why RingSize.app
Free ring size app with the actual ring size chart on screen.
The free virtual ring sizer with an actual ring size chart on screen
RingSize.app is a free virtual ring sizer, a ring size calculator, a ring measuring app and a ring size finder in one. Unlike a static actual ring size chart on screen image, this is a true digital ring sizer: it calibrates to your screen so the actual ring size on screen matches real millimetres. Use it as an online ring sizer, an actual ring size chart on phone, or a ring sizer tool on tablet — completely free, with no download and no sign-up.
How our ring size app works (and why a virtual ring sizer beats a printed chart)
Most "actual ring size chart on screen" pages are just static images — they only print or display at true size if your browser and printer happen to be at exactly 100% zoom, which is rarely the case. Our ring sizer app free tool fixes this with a one-time calibration: place a credit card or local coin on screen, match the outline, and we save the scale factor. From that point on the ring size chart on screen is accurate to your specific device — desktop monitor, iPad, iPhone, or Android. The same calibration powers the ring measuring app mode (place an existing ring on screen) and the ring size finder mode (wrap a strip of paper around your finger and measure the mark on our calibrated ruler).
Why choose this free ring sizer app?
- Actual ring size chart on screen calibrated to your device — not a generic image
- Free ring size app with no registration, no download, no hidden cost
- Virtual ring sizer + ring measuring app + ring size finder in one tool
- Ring size calculator app covering US, UK, EU and Japanese standards
- Digital ring sizer that works on phone, tablet and desktop
- Ring sizer on phone free — no app store install
- Privacy-first — every measurement stays on your device
Perfect for:
- Engagement & wedding ring shopping
- Online jewellery purchases (Etsy, Tiffany, Mejuri, Cartier…)
- Resizing an heirloom or vintage ring
- Sizing a gift ring without ruining the surprise
- Converting between US, UK, EU & JP ring sizes
- Sizing both women's and men's rings (US 3 – 13)
Supported measurements:
- US ring sizes 3 – 13 (¼-size precision)
- UK ring sizes F – Z
- European sizes 44 – 72
- Japanese sizes 4 – 27
- Inner diameter (mm)
- Circumference (mm)
Measure ring size on phone — free, no install
RingSize.app is also a fully-featured ring sizer on phone free. Open the site in any mobile browser to access an actual ring size chart on phone, calibrate with a credit card, then place your ring on the screen. On desktop, tap "Send to phone" to get a QR code that opens the online ring sizer on your mobile in one scan — perfect when you want to measure with the ring directly on the display. The result is a precise ring size measurement app experience without ever installing anything.
Welcome to the free Ring Size App
RingSize.app is a free, easy-to-use virtual ring sizer that lets you place your actual ring directly on the screen to get an accurate ring size measurement. Our screen-calibration system makes it a true digital ring sizer — the on-screen ring matches real-world millimetres on any device, so it doubles as an actual ring size chart on screen, an actual ring size chart on phone, or a portable ring measuring app.
How to use this online ring sizer in 3 steps
Our ring sizer online works in seconds. Just follow the steps below to find your ring size for free.
1. Calibrate your screen:
Place a credit/debit card or a local coin (US Quarter, 1 Yuan, 1 Euro, Canadian 25¢, ₹5 Rupee, $1 AUD, or $1 SGD) on your screen and slide until the on-screen outline matches the object perfectly.
This is the step that turns a generic virtual ring sizer into a precise digital ring sizer. Calibration is saved per-device, so future visits skip straight to measuring.
2. Place your ring (or measure your finger):
With the ring measuring app mode, place your ring on the screen and drag the slider until the gold circle matches the inner edge. Prefer to measure without a ring? Use the ring size finder mode: wrap a strip of paper around your finger, mark where it meets, then measure that mark on our calibrated ruler.
3. Read your ring size:
The result panel shows your US ring size with conversions to UK letter sizes, EU and Japanese standards, plus diameter and circumference in millimetres — everything a jeweller might ask for. Your last measurement is remembered for next time.
Additional features of this free ring size app
- Universal calibration: any standard credit card (ID-1, 85.60 × 53.98 mm worldwide) or major coin works
- International sizing: US, UK, EU and Japanese conversions side-by-side
- Send to phone: QR code from desktop opens the ring sizer on phone instantly
- Save results: your last measured size persists for future visits
- Mobile-first design: works perfectly as an actual ring size chart on phone
- No downloads required: use directly in any modern browser
Why choose RingSize.app?
- Accuracy: screen calibration means measurements are within ±0.05 mm — comparable to a jeweller's mandrel
- Convenience: no jeweller visit, no plastic ring sizer kit waiting in the mail
- Free: the entire ring size calculator + ring measuring app + ring size finder is free, forever
- Privacy: all measurements happen locally in your browser — nothing is uploaded
- Universal: works for any ring style and finger, women's and men's, US 3 through 13