What actually fits: a size guide measured across our own range

Three numbers on a product page tell you the outside of a bag. What you want to know is the inside, and the two are further apart than they look.

This piece does three things. It explains where the missing inches go, it gives the real footprint of the objects everybody carries, and it prints a ladder of our own silhouettes so you can compare shapes without opening one page at a time.

Nothing here is a rule of thumb borrowed from somewhere else. The measurements are ours.

Where the inches go

A bag described as ten inches wide is ten inches on the outside, at the widest point, usually across the base. Four things eat into that before you put anything in.

• The fabric and any padding. On a quilted bag that is a quarter to half an inch on each side.
• The lining and its seam allowance, another eighth of an inch each side.
• Interior pockets sewn to the lining, which take depth out of the main compartment along one whole face.
• The taper. Very few bags are a box. A crescent is widest at the base and narrower at the zip, and the zip is where your hand goes in.

The practical rule from measuring our own range: subtract about an inch from the stated width and an inch and a half from the stated height to get the usable opening. A ten by seven inch bag behaves like a nine by five and a half inch space.

Depth is the number people ignore and the one that decides most of it. Under three inches of depth, a bag holds flat things. Over four, it holds a bottle standing up. That single threshold changes what a bag is for.

What everyday things actually take up

We measured what our own team carries, with a ruler, on a table.

Two of those rows do most of the damage. Sunglasses in a hard case need two inches of depth and refuse to bend. A bottle needs eight inches of standing height and will lie down and leak if it does not get them.

If you carry both every day, a bag under four inches deep will annoy you no matter how wide it is. That is the most useful sentence in this piece.

The ladder, measured across our range

Here is every silhouette we make, with the range of published dimensions and what each one comfortably holds. Compare across rows rather than reading one.

Read the ladder against your own list. Most people find they have been buying one step too small and compensating by carrying a second bag.

What the numbers never tell you

Two bags with identical dimensions can feel a size apart, and three things explain almost all of it.

How wide the opening is

A zip that runs the full width of the top gives you the whole bag. A zip that stops two inches short at each end gives you a slot. On a crescent the curve makes this worse, because the opening follows the curve and your hand does not.

Test it the way you will use it: reach in with one hand, without looking, and try to find a set of keys at the bottom. If that takes two hands, the bag is smaller than its numbers.

Where the pockets are

An interior pocket sewn flat against the lining costs almost nothing. A gusseted pocket that stands away from the lining eats an inch of the main compartment along its whole length, and that inch is usually where a bottle wanted to go.

Outside pockets are free volume. They take nothing from the inside of the bag, and a phone in an outside pocket is a phone you stop hunting for.

Whether the base is flat

A bag with a flat, boxed base holds its stated depth all the way down. A bag whose sides meet at the bottom holds its depth at the top and nothing at the bottom. Look at the base seam. If it runs as a rectangle, the depth is real.

How to measure a bag you already own

The fastest way to buy the right size online is to measure the bag you like and the bag you do not, and to know which numbers made the difference.

1. Empty it. Stand it up, or hold it in shape if it is soft.
2. Width, across the base at its widest, not across the top.
3. Height, from the base to the top of the body, ignoring the handles.
4. Depth, front to back at the base. This is the number that decides the bottle.
5. Strap drop, from the top of the strap at rest to the top of the bag. For a crossbody, measure the whole loop instead.

Write the five numbers on your phone. Every piece in our range prints the same measurements where the maker publishes them, so the comparison takes seconds rather than guesswork.

Packing order, which matters more than size

Two people with the same bag and the same things can have completely different days, and the difference is the order they put them in.

The orthopaedic guidance for backpacks says it plainly, and it holds for every bag with a strap.

1. Heaviest item flat against the side that touches your body. That is the bottle, always.
2. Flat things next, standing on edge like files in a drawer rather than stacked. Stacked things are only reachable from the top.
3. The thing you need most often goes in an outside pocket, not the main compartment. Phone, transit card, keys.
4. Anything that leaks, melts or bleeds ink goes in its own pouch. A pen without a lid has cost more linings than rain ever has.
5. Leave a hand's width of slack. A bag packed to the zip cannot be searched with one hand while walking.

The airport section

A bag that works all week can lose an hour at security. Two things decide that, and only one of them is the bag.

Liquids

The rule is published and specific.

The practical consequence is a clear quart bag that has to come out fast. Keep it in an outside pocket or in the top third of the bag, never at the bottom under a laptop. That one decision is the difference between ten seconds and three minutes at the tray.

The personal item

Airlines set their own sizes for the bag that goes under the seat, and they differ from one carrier to the next. We are not going to print a number here and let it go stale. Check the personal item dimensions your carrier publishes before you fly, and measure your bag yourself rather than trusting a description, for all the reasons in the first section.

What we can say about our own pieces is what they measure, and every travel piece in the range carries its dimensions where the maker publishes them.

Organisers, and whether they help

A bag organiser is a fabric insert with pockets that lifts out of one bag and into another. People either swear by them or find them a waste of an inch. Both camps are right, and which one you land in depends on your bag.

In a deep, soft bag an organiser is a genuine upgrade. It stops the pile at the bottom, it makes a slouchy shape searchable, and it means swapping bags takes ten seconds rather than five minutes on a table.

In a bag under three and a half inches deep it is a mistake. The insert has walls, the walls have thickness, and you have just traded most of your depth for tidiness. In that size, a single zip pouch for small things does the same job and costs nothing.

We do not sell organisers. We do make small pouches and wristlets that people use as one, which is the reason that department exists at all.

The weekend question

Two nights away is the size everybody gets wrong. A cabin case is too much and a day bag is not enough, and the gap between them is where a soft duffle lives.

Twenty-five litres is the number that works for most people. Two changes of clothes, a pair of shoes, a wash bag and a charger, with room to close the zip without kneeling on it. Below twenty litres you start leaving the shoes behind.

A quilted duffle has one advantage a wheeled case cannot match. It folds flat on the way out and comes back full, so a weekend bag can travel inside a suitcase for the outbound leg and carry the extra on the way home.

It has one disadvantage too, and it is the same one as every soft bag. Everything is on your shoulder. For a train platform and a taxi that is fine. For a long airport walk with a connection, wheels win and we are not going to pretend otherwise.

When to size up, and when not to

Size up when you carry a bottle every day, when sunglasses live in a hard case, or when a laptop travels more than twice a week. All three are depth problems and no amount of width fixes them.

Do not size up because of one unusual day. The umbrella in July and the charger for a laptop that stays at home are how a small bag becomes a heavy one. A bigger bag gets filled to its new size within a fortnight, every time.

The other honest answer is two bags. A small crossbody for five days a week and a tote for the two days you carry a laptop costs less than one bag that does neither well, and your shoulder notices the difference by Thursday.