What size trash can for a family of 4?

A 13-gallon kitchen can, emptied every two days, and a 64-gallon wheeled cart outside. That combination fits the large majority of four-person households. If you do not recycle or compost, step the kitchen can up to 15 or 16 gallons rather than to 20 — you keep the standard bag and gain most of the capacity. If you do sort seriously, a 13 will feel oversized and that is fine.

The reason this question does not have a single clean answer is that household size is a weaker predictor than what the household does. Four people who compost, recycle and eat out twice a week put less in a landfill can than two people who do none of those things.

The EPA's most recent published Facts and Figures put US municipal solid waste generation at 292.4 million tons, or 4.9 pounds per person per day. For four people that is around 19.6 pounds a day on paper.

Treat that as an upper bound rather than a target. Municipal solid waste includes commercial and institutional waste streams, not only what leaves your kitchen, and it counts recycling and composting alongside landfill waste. The useful takeaway is the direction rather than the number: a four-person household generates a lot, and most of the volume is packaging rather than food.

Which is why the single most effective change to the size of can you need is not buying a bigger can. It is taking the recycling and the food waste out of it. A countertop compost bin changes the size you need more than any can feature does.

Here is a one-week test that beats any rule of thumb. Keep the can you have, and for seven days note when it gets full rather than when you empty it. Then match the result:

• Full in under a day: you are undersized by a lot. Go to 15-16 gallons, or add a second stream for recycling.
• Full every 1-2 days: 13 gallons is right. This is where most families of four land.
• Full every 3-4 days: you could drop to 8-10 gallons and the kitchen would smell better for it.
• Never quite full before you empty it anyway: your can is already too big, and the waste is sitting long enough to be the smell you are noticing.

Buying one big can instead of two streams

A 20-gallon can for everything is almost always worse than a 13-gallon can plus a recycling bin. The landfill stream in a sorting household is small, the recycling stream is bulky and dry, and mixing them means the bulky dry stuff pushes the wet stuff down where it sits. Dual-compartment cans.

Sizing for the worst week of the year

Christmas and birthdays are not a reason to live with an oversized can for the other fifty weeks. Use a bag on the floor for one week a year and buy for the ordinary weeks.

Forgetting who carries the bag out

Thirteen gallons of wet kitchen waste is heavier than people expect, and a thin bag full of it is what splits on the stairs. If the aim is for a teenager to take the trash out, a smaller can quietly makes that likelier. Why trash bags split and what to buy.

Matching the cart to the house instead of the hauler

Outside, the constraint is what your hauler will lift and what you can steer down the driveway. A full 96-gallon cart on a sloped drive is genuinely difficult. 64 versus 96 gallon carts.