Best Size Recommendation Apps for Shopify

The best size recommendation app for Shopify is the one that sizes shoppers with information they'll actually give and matches it to your own chart. For most fashion stores, the realistic shortlist is ZeDaq.ai for photo-based sizing, Kiwi Size Chart & Recommender for chart-led sizing, and Virtusize or Sizebay for brands that want a managed fit service.

ZeDaq.ai publishes this blog. Competitor details come only from each company's own public page or Shopify App Store listing, checked November 2026. If you want try-on images as well as sizes, our ranked list of try-on apps for Shopify covers that side.

What makes a size recommendation app good?

A size recommendation app turns information about a shopper into one size label from your chart. A good one gets four things right:

• The input is easy. Shoppers abandon long forms, and some won't share a photo. The fewer taps, the more people finish.
• It uses your chart. A generic chart ignores how your brand cuts. Your own ranges should drive the answer.
• It handles in-between shoppers. The app should have a clear rule for someone between two sizes.
• You can maintain it. When patterns change, you should be able to update ranges without a support ticket.

There are two main ways apps collect information. A fit quiz asks questions, such as height, weight and fit preference. A body scan measures the shopper from a photo. Our guide to size recommendation vs fit quiz apps compares the two approaches in depth.

Which size recommendation apps should Shopify stores consider?

ZeDaq.ai: photo scan matched to your chart

ZeDaq.ai sizes shoppers with a 30-second body scan. The shopper uploads one photo and types their height. The measurements are matched to your own size chart, with a generic UK, US, EU or AU chart as a fallback.

You enter charts in the Shopify app, one per garment type: tops, outerwear, dresses and bottoms. When a shopper falls between sizes, the scan sizes up to the largest relevant measurement.

"Find my size" sits inside the same window as AI virtual try-on. The shopper sees your real garment on their own body, then gets a size. You install it from the Shopify App Store and switch on its app embed in the Theme Editor.

Kiwi Size Chart & Recommender: chart-first with a recommender

Kiwi's Shopify App Store listing (checked November 2026) names the app "Kiwi Size Chart & Recommender," built by Staytuned. It shows a rating of 4.7 from 1,242 reviews.

The listing says you can "Import unlimited size charts from images, product descriptions, or CSV." It also lists "AI-powered size recommendations," guides that auto-apply to new products, and units that switch based on the shopper's location.

Plans on the listing are Free, Premium at $7.99/month, Plus at $14.99/month and Ultimate at $26.99/month. Paid plans include a 14-day free trial, and the listing notes extra charges may apply based on order volume on Plus and Ultimate.

Virtusize: fit intelligence for larger catalogs

Virtusize describes "AI fit intelligence" on its homepage (checked November 2026). The page says shoppers get their size in under 30 seconds and that it covers apparel, footwear, bags and kids.

The homepage lists Shopify among its platforms and shows "Virtusize for Shopify" at "$1 for the first month, then from $39/mo." Setup uses two script tags. Note that its Shopify App Store page said the app "is not currently available on the Shopify App Store" when we checked, so ask Virtusize how Shopify setup works today.

Sizebay: a managed size and fit suite

Sizebay's homepage (checked November 2026) calls its Size & Fit product "The world's leading size recommendation tool." For clothing, it says shoppers get a size "with only their height, weight, and age."

The homepage also lists shoe sizing, size charts and photo try-on. It doesn't name Shopify or show prices, so contact Sizebay for setup and cost details.

How do these Shopify size apps compare?

Competitor details come from each linked page, checked November 2026.

App	What the shopper gives	Chart source	On Shopify App Store	Listed price
ZeDaq.ai	One photo plus height	Your own chart, generic fallback	Yes	Free to $299/mo
Kiwi	Recommender inputs not listed	Imported from images, text or CSV	Yes	Free to $26.99/mo
Virtusize	Not detailed on homepage	Uploaded as CSV, Excel or PDF	Listing says not currently available	From $39/mo after $1 first month
Sizebay	Height, weight and age	Not detailed on homepage	Not named on homepage	Not shown

A size recommendation app depends on a good chart. If you don't have one yet, start with our comparison of the best size chart apps.

Which app fits which store?

• A small store with one or two garment types. Kiwi's Free plan or ZeDaq.ai's Free plan lets you test without cost.
• A store where fit questions fill the inbox. A photo scan gives shoppers a size from their real measurements rather than an estimate from weight.
• A store that also wants try-on. ZeDaq.ai puts try-on and sizing in one window. Sizebay also lists try-on with its sizing.
• A large brand with many categories. Virtusize and Sizebay present themselves as managed services, so ask about onboarding and support.

What should you ask each vendor before installing?

App listings and homepages leave gaps. Send the same short list of questions to every vendor, and compare the written answers side by side.

• Who enters and updates the size chart? Some apps let you edit ranges yourself. Others manage charts for you, which is easier but slower to change.
• What happens when a shopper falls between sizes? Ask for the exact rule, and whether you can change it.
• What does the shopper see if no chart exists? A blank result is worse than a generic fallback.
• Which theme setup is needed? App embeds and app blocks need an Online Store 2.0 theme.
• What data is collected from shoppers? Ask what is stored, for how long, and whether photos leave the shopper's device.
• How is usage billed? Ask whether you pay per order, per recommendation or a flat fee, and what happens if you go over.
• How do you uninstall cleanly? Check that removing the app also removes its code from your theme.

Keep the answers in one document. They make the final choice faster, and they're useful if the app's terms change later.

How do you test a size app before committing?

Testing takes about an hour. Use real people and your real chart.

1. Pick one difficult product. Jeans are ideal because waist, hip and inseam all matter.
2. Gather five people who know their size in your brand. Staff, friends or loyal customers work well.
3. Run each app on a phone. Record the size it suggests for each person.
4. Compare with the size they actually wear. Count exact matches and near misses.
5. Time the flow. Note how many seconds each person takes from tap to result.

A worked example scorecard

Use a simple table like this, and fill it in for each app you test:

Person	Usual size	App suggestion	Match?	Time taken
A	M
B	L
C	S
D	XL
E	M

The app with the most matches and the shortest time usually wins. If two tie, pick the one your team finds easier to update.

Denim is the hardest test for any app, because fit varies by cut and stretch. Our guide to sizing for denim brands explains how to build charts for rigid and stretch jeans.

How do you set up ZeDaq.ai on Shopify?

1. Install the app and approve its permissions.
2. Open the size chart screen, choose a garment type and enter a minimum and maximum for each size.
3. In Online Store → Themes → Customize, open App embeds and turn on the ZeDaq.ai embed.
4. Set the garment type in the embed settings so the scan uses the right chart.
5. Test on your phone with your own photo and height.

What does ZeDaq.ai cost?

ZeDaq.ai lists its plans on the pricing page:

Plan	Price	Notes
Free	$0	3 try-ons, 3 measurements and 5 invoices a month
Micro	$14/mo
Starter	$49/mo
Growth	$129/mo
Scale	$299/mo

Every paid plan has a 3-day free trial with no card required. Each size scan uses one measurement from your plan.

FAQs

Do size apps work without my own size chart?

Some do. ZeDaq.ai falls back to a generic UK, US, EU or AU chart until you add yours, but your own chart gives answers that match your labels.

Is a size chart app the same as a size recommendation app?

No. A chart app displays your size guide. A recommendation app picks one size for the shopper. Kiwi does both, according to its listing.

Does the shopper need an account to get a size?

Not with ZeDaq.ai. The shopper uploads a photo and types their height on your product page, with no sign-up or download.

Can I use different charts for tops and trousers?

Yes. In ZeDaq.ai you add one chart per garment type, and the embed setting tells the scan which chart to use.