The complete guide
The Buyer's Guide to Tent Footprints and Ground Sheet Tarps
The problem with pitching straight onto the ground
Most people discover the need for a ground sheet the hard way. You pitch in the late afternoon on grass that looked fine, and by morning the inside of the tent floor is cold and clammy under your mat. Or you pack up after a weekend and notice tiny abrasions on the floor fabric, the kind that eventually become pinholes, and pinholes become wet socks.
Tent floors are the hardest-working part of any tent and usually the least protected. They get dragged across gravel during pitching, knelt on, walked on with grit stuck to bare feet, and left sitting on soil that holds moisture long after the rain stops. The floor fabric is also the part you cannot easily patch in the field without it showing.
A footprint fixes this cheaply. It is a sacrificial layer between the ground and the tent, and it costs a fraction of what a tent does. This one is a 1.8 x 2.2 m sheet of Oxford fabric with a waterproof treatment, army green, weighing 367 g, with metal grommet eyelets around the edge and its own storage pouch.
How a waterproof camping tarp actually works
There are two jobs happening at once. The first is abrasion. Oxford cloth uses a tight basketweave, which spreads wear over a lot of crossing threads rather than letting a single sharp stone work on one strand. That is why Oxford turns up in bags, covers and ground sheets rather than in lightweight tent canopies.
The second job is moisture. Soil holds water, and that water moves upward by capillary action. Lay a waterproof barrier down and that upward path stops at the sheet. Your tent floor is still doing its own waterproofing job, but it is no longer fighting continuous contact with damp earth all night. On a dewy morning, the practical result is that you fold away a dry tent instead of a wet one, which matters more than it sounds when you have three more nights to go.
The grommets add a third job that has nothing to do with the ground. Run cord through the eyelets and tie off to trees, awning poles or a roof rack, and the same sheet becomes a shade over the camp table or a rain cover for a cooking area. Give it a slope so water runs off one edge rather than collecting in a sag.
Who this suits
Car campers get the most obvious benefit. The weight is irrelevant when you are driving, and the tougher fabric handles whatever a caravan park or a bush site throws at it.
Walkers and hikers can still carry it. At 367 g it is heavier than a thin plastic sheet but a lot more durable, which suits people who camp often and would rather buy once. If you are chasing the lightest possible pack for a long through-hike, that is a genuinely different calculation and a thinner sheet may win.
Families who camp a few times a year tend to love the second uses more than the first. The same sheet is a picnic mat at the park, a beach blanket, a cover over bikes on the trailer and a mat for sorting gear at the campsite so nothing ends up in the dirt. For a lot of households this stays in the car permanently.
It also works for anyone wanting a simple ground sheet for camping without buying a model-specific footprint from a tent brand, which usually costs considerably more and only fits one tent.
How to choose the right size
Start with the tent floor, not the tent name. Manufacturers measure tents in different ways, and the number on the box often includes the vestibule or the fly footprint rather than the sleeping floor.
Lay a tape measure across your tent floor at its widest and longest points. You want a footprint that matches or sits slightly inside those numbers. This medium size is 1.8 x 2.2 m, which lands nicely under many two to four person dome tents.
If the footprint turns out slightly larger than the tent, fold the excess underneath. Do not leave an edge sticking out past the tent walls. Rain runs off the fly, lands on that exposed lip and gets channelled straight under your floor, which is the opposite of what you wanted. A footprint that is a touch too small is far better than one that is too big.
For non-tent use, bigger is generally better. A sheet that feels oversized under a tent is about right as a picnic mat for four people or as a shade canopy.
Getting the best out of it on site
Clear the pitch first. Walk the area and kick away the stones, pine cones and broken sticks. The footprint protects your tent, but nothing protects the footprint except you.
Peg the corners through the grommet eyelets before you pitch, especially if there is any breeze. A loose sheet will fold itself over just as you start threading poles, and that is a frustrating minute of your life.
Pitch the tent on top, then check the edges once more. Anything poking out gets tucked in. If you are on a slope, make sure the uphill edge in particular is tucked well under.
When using it overhead, keep the tension even. Pull from several eyelets rather than cranking one corner hard, and always build in a slope so water sheds. A flat tarp in rain will collect a pool, and a pool is surprisingly heavy.
Looking after it
The single most important habit is drying. Shake off the loose dirt and sand at the campsite, then make sure the sheet is properly dry before it goes into long-term storage. If you have to pack it wet on a rainy morning, unfold it over a railing or across the lawn when you get home and let it dry out within a day or two. Damp fabric folded in a pouch grows mildew, and mildew smell is close to permanent.
For cleaning, cool water, a sponge and a mild soap do the job. Rinse it off and hang it up. Keep it out of the washing machine and the tumble dryer, skip the bleach and solvents, and do not put it near a hot stove or open flame.
Store it loosely folded in its pouch somewhere cool and dry. Leaving any coated fabric baking in a car boot through summer after summer shortens its life.
A note on what it does not do
Two honest limits. Ultraviolet protection is listed as false for this item, so if you are rigging it overhead, treat it as shade and glare relief rather than sun protection for skin. Hats and sunscreen still apply.
It also is not an insulating layer. It blocks moisture, which helps you feel warmer, but the actual warmth comes from your sleeping mat. Do not skip the mat because you have a footprint.
The short version
A tent footprint is one of those bits of kit that quietly pays for itself. It takes the grit and the ground damp so your tent floor does not have to, and your tent lasts more seasons as a result.
This one is a 1.8 x 2.2 m Oxford sheet with a waterproof finish, army green, 367 g, with grommet eyelets and a storage pouch. Measure your tent floor, tuck any excess underneath, peg it down, and dry it before you put it away. Use it as a picnic mat and a shade tarp the rest of the year, and it earns its spot in the car without much thought from you.