How to Choose the Right Tarp Size: Buying Guide for Every Use

Updated: May 27, 2026

The Rule: Always Size Up

When your calculated tarp size falls between standard sizes, always choose the next size up. A tarp that’s 2 ft too long on one side is easily managed by folding the excess. A tarp that’s 2 ft too short leaves a gap that defeats the purpose.

Choosing Tarp Size by Use Case

Pool and Pond Cover

Measure the pool surface (length × width for rectangular, diameter for round)
Add 2 ft overhang per side minimum
For inground pools with a coping lip: the tarp must clear the coping — add 3–4 ft per side instead

Pool Size	Tarp Size (with 2 ft overhang)
12 × 24 ft	16 × 28 → buy 16 × 30
15 × 30 ft	19 × 34 → buy 20 × 35
16 × 32 ft	20 × 36 → buy 20 × 40
18 × 36 ft	22 × 40 → buy 25 × 40

Woodpile Cover

Woodpiles: typically 4–8 ft wide, 4–8 ft high, 4–16 ft long
Add height × 2 to both length and width
Add 1 ft ground overlap per side

For a 4 × 8 × 6 ft woodpile (4 ft wide, 8 ft long, 6 ft high), 1 ft overlap:

Tarp length = 8 + (6×2) + (1×2) = 22 ft
Tarp width  = 4 + (6×2) + (1×2) = 18 ft → buy 20×25

Camping Ground Sheet

Footprint should be slightly smaller than tent floor to prevent pooling
No overhang needed — tent covers the footprint
Or: buy 1 size up and fold under the edges for extra protection

Tent Size	Ground Sheet
2-person (7 × 7 ft)	8 × 8 ft tarp, fold edges under
4-person (8 × 10 ft)	8 × 10 or 10 × 12 ft tarp
6-person (10 × 14 ft)	10 × 14 or 12 × 16 ft tarp

For tarp shelters (using the tarp as a rain fly): allow 4–6 ft extra beyond the shelter footprint on each side that pitches out. See Tarp Size for Camping for lean-to, A-frame, and hammock fly sizing.

Vehicle Cover

Measure vehicle length and width (including mirrors)
Add 2–3 ft per side overhang to reach the ground or window line

Vehicle	Cover Size
Motorcycle	10 × 12 ft
ATV / UTV	12 × 16 ft
Average car / SUV	16 × 20 ft
Full-size pickup	16 × 20 or 20 × 25 ft

Emergency / Roof Tarp

For temporary roof damage (leaks, storm damage):

Measure the damaged section plus 4 ft overlap on all sides
The tarp must extend over the ridge line and 4 ft down the undamaged slope
Secure with 2 × 4 wood battens nailed through the tarp into the deck

For a 12 × 12 ft damaged area:

Tarp length = 12 + (ridge extension 4 ft) + (4 ft per side) = 24 ft minimum
Tarp width  = 12 + 4 + 4 = 20 ft minimum → buy 20 × 25 ft

Tarp Weight for the Job

Job	Minimum Rating	Why
Camping ground sheet	2–3 mil	Light use, short term
Casual outdoor cover	3–5 mil	Standard PE tarp
Hay / silage stack	5–8 mil	UV exposure, wind stress
Woodpile (year-round)	5–6 mil, UV treated	Sun and moisture
Construction/roof	8–12 mil	Heavy use, repeated repositioning
Flatbed truck	10–20 mil vinyl	Road vibration, debris impact

When to Order Custom

Standard tarps cover most situations. Order custom when:

Needed dimensions fall more than 5 ft past the largest standard size in either dimension
Shape is non-rectangular (L-shaped, circular)
You need specific grommet spacing or reinforced edges
Volume purchase (50+ tarps) — custom is cost-competitive at scale

Agricultural suppliers (Mytee Products, Canopies and Tarps, Tarps Now) offer custom sizes with 2–3 week lead times. For material selection guidance, see the Tarp Types Guide.

Use the Tarp Size Calculator — enter your dimensions and get an instant recommendation.

See also: Tarp Size Formula and Tarp Types Guide.