How big a tarp for one person?

Question

Based on this question: Best tarp setup for camping on the plains? I wonder how big a tarp I need to carry for one person, for emergency use only.

I am hoping to do a multi day hike where I will usually sleep under roofs, like hotels, hostels or even in private homes. For that I expect to carry a good sleeping bag and a light duty mat, just enough to keep me isolated from the ground.
But as I will cross a huge distance solo (I hope from within the Netherlands to Santiago de Compostella, on the west coast of Spain,) I will not be sure to find a roof to sleep under every day and may find myself in bad weather without a lot of advance warning. I would like to know that I can spend the night safe from the weather at need.

I will carry (and likely use) a walking stick, most likely one of the ones you can adjust the length, but want to avoid bringing other supports if I can get away with not having one. If there are usable trees or other supports I will use them, but I might end up in the middle of a campsite without usable supports. I will also have string, more than needed for this, as I am a knot tyer and will always have something to tie with.

I understand the instructions in the linked question, but what I do not understand is how big is the smallest tarp I can get away with for one, not too tall person. (I am 1.65 meter, 5'5", and a little overweight but not in a way that I expect to be of influence in this.)

The other reason to carry a tarp is that I might get into really bad weather and need more protection than my rain gear will provide.

I will appreciate if you can link to examples of tarps for sale as well as or instead of actual size suggestions. And as I am mostly gathering information well in advance of travel, it does not matter to me whether they are in Europe or elsewhere in the world. (Target departure is at least 2 years from now, can be a few years after that.)

Answer 1

Your bare minimum option (in terms of weight, size and cost) would be plastic sheeting, eg a heavy-duty garbage bag or emergency survival blanket (the kind that's a plastic sheet with a shiny metallic side). To use plastic sheeting a tarp, wrap the corner of the sheet around a smooth pebble, and tie your cord around the pebble. You can see this method demonstrated in several episodes of the show Survivor Man, where he uses garbage bags for emergency shelter. Here's another example on Youtube. At a bare minimum, you need a plastic sheet as large as a heavy-duty garbage bag (cut along three edges and opened up to make a single layer): 45 x 76 inches; 114 x 193 cm.

If you go the plastic sheet route, expect it to be a single-use shelter. In practice, you may be able to get multiple uses out of a plastic sheet, but don't count on it. You should absolutely practice setting this up beforehand. Bring some tape to patch holes in your tarp.

Pros of a plastic sheet:

• very inexpensive
• lightweight

Cons of a plastic sheet:

• single-use
• not very sturdy; may not survive strong winds
• takes longer to set up

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In terms of actual tarps intended for this purpose, I got some excellent results by searching for "miniature survival tarp." Note the word survival - a survival tarp supposed to keep you alive, but not necessarily comfortable. Here's a list of links. I'll summarize my findings below.

• https://effortlessoutdoors.com/best-camping-tarps/
• https://theprepared.com/gear/reviews/tarps/
• https://survivalcache.com/easy-survival-tarp-shelter/

The smallest tarp size any source recommended was 5 x 7 feet (152 x 213 cm). The actual product they linked to was a basic emergency survival blanket with grommets in it. One source said 8 x 8 feet (244 x 244 cm) is the bare minimum. A few brands are available in 10 x 7 foot (305 x 213 cm) size, but the most commonly available size is 10 x 10 ft (305 x 305 cm).

Prices in this category range from (roughly) $30-$100. At the upper end, you can get lighter-weight and/or sturdier construction. At the lower end, expect to carry more weight and/or have a flimsier product.

Pros of a purpose-made survival tarp:

• tradeoff between weight and price: can be lightweight but expensive, or heavy but cheap
• sturdier than a plastic bag
• faster to set up

Cons of a purpose-made survival tarp:

• price and/or weight

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Whatever option you go with, be sure to practice setting it up in a non-emergency situation. Get under the tarp with your backpack and have someone spray the tarp with a garden hose. If you get wet, adjust your setup accordingly. Figure out how much cord it takes, and make sure you have that much with you. Decide whether to purchase and carry tarp stakes, or plan to improvise them by whittling or tying to rocks.

Answer 2

My tarp is 150 cm x 240 cm, and it's worked well for me when a sudden storm came up. In a storm that lasted for more than half a day, it would be cramped and uncomfortable.

Answer 3

A few more thoughts:

• The necessary size of tarp for rain + wind depends a lot on how much water you'd be willing to get onto/into your sleeping bag. E.g. I tend to be more picky when I'm out with my good down bag than when I'm out with my old synthetic fiber bag. In the end, that only trades weight/volume in sleeping bag <-> weight/volume of tarp...

• For bad weather (rain + wind/storm), there's also the question of dealing with the water on the soil. When I expect rain, I take a larger tarp that I wrap to form a ground sheet + roof.
  IIRC the smallest tarp I've used is 3 x 3 m.

• If you can rely on using trees: tarp + hammock can be done with a smaller tarp.

• IMHO tarps are comparably inefficient for single persons, but very good for groups: 3x3 is a tight and not very rain-proof squeeze for 1 person, 4 x 6 m easily houses 4 - 6 people (both ground sheet + roof "wrap")

Answer 4

How big a tarp for one person?

That will depend on several conditions, such as the height of the individual doing the camping and the possibility of bad weather to be possibly encountered.

A smaller framed person and the expectation of bad weather for a short duration could get by on a smaller tarp, say 10’ x10’, about 3 x 3 meter.

However, I would feel more comfortable with a 10’ x 12’ (3 x 3.5 meter) tarp. This gives one a little more movement under the tarp in bad weather as well as keeping your gear dry, next to you!

You could go the 12’ x 16’ (3.5 x 5 meter) route, but that is simply too much weight and space you have to carry.

In Spain, during the summer months, I would go with the 10’x 10’ route as towns villages and hostels are generally not too far apart and the Spanish are very accommodating. This is especially true along the Way of St. James. (Metric sizes rounded to the nearest likely tarp sizes.)