A work backpack under $100: six checks before you buy

A $70 backpack used 500 times costs 14 cents a day. You carry it every workday. That makes it one of the better places to spend.

The wrong one will make your shoulders ache and your zips fail in a year. These checks help you avoid it.

Six checks

1. Laptop fit. Measure your laptop and check the compartment size, not just the label. A padded sleeve that sits off the floor of the bag protects against drops.

2. Straps. They should be wide, padded and adjustable. Thin straps dig in once the bag weighs more than a few pounds.

3. Back panel. A padded, ventilated back is more comfortable for long commutes. A flat panel is fine for short ones.

4. Zips. Look for chunky, smooth zips. They are the first thing to go. Check the stitching around them.

5. Fabric. Tightly woven nylon or polyester is common and tough. Look for a denier rating, with higher numbers usually meaning thicker fabric. Water resistant coating helps with rain but does not make the bag waterproof.

6. Warranty. A multi-year warranty means the maker expects the bag to last.

Pockets: how many do you need?

Fewer than the listing claims. A main compartment, a laptop sleeve and one or two quick-access pockets cover most days. More compartments add weight and more zips to break.

At this price you get / do not get

You get: - Padded straps and a laptop sleeve - A water-resistant fabric - A bag that handles daily use for a few years

You do not get: - Fully waterproof construction - A lifetime warranty at the lowest end - Luxury materials

Walk away if

• The laptop sleeve is a thin fabric pocket.
• The straps are narrow and unpadded.
• Reviews mention zips breaking in the first months.
• The listing has no dimensions or capacity.
• It is much cheaper than similar bags and has no explanation.

Size and weight

Capacity is listed in liters. Around 20 to 25 liters suits a laptop and daily items. Fill the bag with your usual load at home and wear it for a while. If it hurts on day one, it will hurt on day 200.

If you want the same bag to double as a travel bag, check it against airline size limits. For a dedicated carry-on, read the carry-on guide. To see how a daily-use item beats a cheaper one over time, read cost per use explained.