Size Guide

Last updated: October 31, 2026

At Mug Mellow, “size” means capacity: how much a mug, travel mug, tumbler or kids cup holds. This guide lists every capacity in the shop with its millilitre conversion, explains what each size feels like in everyday use, and helps you choose between two options when a design offers both. It also explains how sizes affect the print, why long names and family lists suit a bigger mug, and what to do if the size you chose turns out to be wrong. If you still cannot decide, email support@mugmellow.shop; we reply within 24 hours on business days.

1. How we measure a size

Every size in the shop is stated in US fluid ounces (fl oz), with an approximate conversion to millilitres. One US fluid ounce is about 29.6 ml, so the conversions below are rounded to the nearest 5 ml. Capacity is measured to the brim, which is more than you would pour in practice: most people leave a finger’s width at the top for milk or for carrying the mug without spilling. A useful rule is that a mug filled comfortably holds roughly 85 to 90 percent of its stated capacity.

We do not list heights, diameters or weights on this page. Product shapes vary between designs, and we only publish numbers we can stand behind. If a particular measurement matters to you, for example whether a tumbler will fit a cup holder or a mug will sit under a coffee machine spout, email us before ordering and tell us the space you have.

2. Every capacity in the shop

3. Choosing between 11 oz and 15 oz

Most ceramic designs come in both sizes, and this is the choice we are asked about most. Here is how we think about it.

Choose 11 oz when

• The person drinks one standard cup of coffee or tea at a time.
• They use a single-serve coffee machine with a short space under the spout.
• The text is short: one name, initials, or a name with a short second line.
• The mug is for someone with smaller hands, or for a mug shelf already full of 11 oz mugs.

Choose 15 oz when

• The person tops up their coffee before they finish it, or drinks large teas.
• The design carries a list: a family of six, a grandparent mug with many grandchildren, several pet names.
• The name is long, especially in script, where connecting letters need space.
• The mug will mostly live on a desk rather than in a cupboard.

For example, a “Nana” mug with six grandchildren’s names reads more comfortably on 15 oz, while a single name in script, such as “Olivia”, looks balanced on 11 oz. If you are buying a matched set, such as a Mr & Mrs pair, both mugs come in the size you choose.

4. Choosing a travel mug or tumbler size

For drinks that leave the house, the deciding question is usually where the cup will sit, not how much it holds.

• A car cup holder: slim shapes such as the 16 oz commuter mug and the 20 oz skinny tumbler are designed for holders. The 40 oz handle tumbler has a tapered base that suits many, but not all, holders.
• A desk or a staff room: a 14 oz travel mug with a handle feels like a regular mug, with a lid for safety around papers and laptops.
• A bag: our lids reduce splashes but none of them are sealed for carrying on their side, so choose a size that can stand upright in the bag you use.
• A long shift or a day outside: 30 oz or 40 oz means fewer refills, at the cost of a heavier cup when full.

Between 20 oz and 30 oz on our pet photo and teacher tumblers: 20 oz is the everyday choice and fits more cup holders; 30 oz suits someone who carries water all day and has room on the desk. The 30 oz option costs $5 more.

5. Choosing a kids cup

For young children, smaller and lighter is easier. The 12 oz straw cup with a snap-on lid suits preschoolers; the 16 oz push-button bottle suits a school bag; the 20 oz handle tumbler is for older children who want a cup like the adults’ cups. The 8 oz ceramic cocoa mug is meant for supervised use at home with warm, not boiling, drinks. Whichever you choose, a short first name or nickname in big letters is easiest for a child to recognise.

6. How size affects your personalisation

A bigger mug has a larger printable area, so the same text is printed with more space around it. That matters most for:

• Lists: family list mugs hold up to eight names and grandparent mugs up to ten; past about five or six names we suggest 15 oz.
• Script: handwritten script reads best up to about twelve letters on 11 oz; longer names suit 15 oz.
• Photos: a wrap photo is printed around more of the mug on 15 oz, so wide landscape photos look especially good there.
• Vertical text: on slim travel mugs and bottles, names run up the side; up to about nine or ten letters fit.

Remember that you type your text in the Order notes box at checkout, and photos are sent by replying to your order confirmation email. We print exactly what you send and do not send proofs, so if you are unsure whether text fits a size, ask us before ordering.

7. If you chose the wrong size

It happens. A 15 oz mug turns out to be too tall for the coffee machine, or a 40 oz tumbler is too big for the cup holder. Here is what to do:

1. Within 24 hours of ordering: email us and we will change the size before production. See Cancel or Change an Order.
2. After delivery, within 60 days: email us for a free return label. Return the item and order the size you want, or ask for store credit, which never expires, and use it on the new size.
3. Refund timing: refunds are issued within 7 days of your return reaching us. See the Refund Policy.

Change-of-mind returns, including size changes, come with a free return label. The full steps are on the Returns & Exchanges Policy page.

Sizing for gifts when you do not know their habits

Buying for someone whose coffee habits you do not know? Look at the mugs already on their shelf, or think about how they drink at work. Someone who refills twice before lunch will thank you for 15 oz; someone who drinks a small, strong cup will reach for 11 oz. When in doubt for a family or grandparent mug with several names, 15 oz is the safer pick because the list needs the room anyway. For a teacher, a 20 oz tumbler with a lid survives a busy classroom better than an open mug.

8. Care differs by material, not by size

Whatever the capacity, care depends on what the item is made of. Ceramic mugs: hand wash recommended to keep the print fresh. Stainless steel travel mugs, tumblers and kids cups: hand wash and never microwave. Heat-reveal mugs: hand wash only, no microwave. Glass: avoid sudden jumps between very hot and very cold. Enamel camp mugs: hand wash; enamel can chip if dropped on hard ground.

9. Sizes offered on each product

The table below lists every product in the shop and the capacity or capacities it comes in. Where two sizes are listed, you choose on the product page. Where a single size is listed, the product is made in that size only.

10. Questions about sizes

Our FAQs answer common questions about cup holders, dishwashers and photos, and the Help Center has a guide to choosing the right shelf. To browse by shape, start with Mugs, Travel Mugs, Tumblers or Kids Cups. For anything else, email support@mugmellow.shop or use Contact Us.