It's about as big as a Dime.
It's about nine-tenths as big as a Penny.
In other words, 0.000000025190 hectares is 0.8840 times the size of a Penny, and the size of a Penny is 1.130 times that amount.(United States one-cent coin) (a.k.a. Lincoln penny, a.k.a. Cent, a.k.a. One cent piece)
The Lincoln penny, in its current design since 1909, has a diameter of 19.05 mm (0.75 in) and an area of 0.00000002850 hectares.
It's about seven-tenths as big as a Nickel.
In other words, 0.000000025190 hectares is 0.7130 times the size of a Nickel, and the size of a Nickel is 1.4030 times that amount.(United States five-cent coin) (a.k.a. Jefferson nickel)
The nickel, in its current design since 1938, has a diameter of 21.21 mm (0.835 in) and an area of 0.000000035330 hectares.
It's about three-fifths as big as a Postage Stamp.
In other words, the size of a Postage Stamp is 2 times 0.000000025190 hectares.(average; United States dimensions)
A typical postage stamp measures an average of 0.0000000400 hectares. One of the most prized stamps among collectors is the US-issued "Inverted Jenny" stamp printed in 1918, which features an upside-down image of Curtiss JN-4 ("Jenny") airplane; a single stamp sold for $977,500 at a 2007 auction.
It's about half as big as a Quarter.
In other words, 0.000000025190 hectares is 0.5450 times the size of a Quarter, and the size of a Quarter is 1.8350 times that amount.(United States quarter-dollar coin) (a.k.a. Quarter dollar, a.k.a. Washington quarter, a.k.a. two bits)
The George Washington quarter, in circulation in various forms since 1932, has a diameter of 24.26 mm (0.955 in) and an area of 0.000000046220 hectares.
It's about one-third as big as a Secure Digital (SD) card.
It's about three times as big as a Nailhead.
In other words, 0.000000025190 hectares is 3.240 times the size of a Nailhead, and the size of a Nailhead is 0.30860 times that amount.(for 11-gauge wire nai)
An 11-gauge nailhead measures 0.0000000077740 hectares. Nails have been used since ancient times; archaeologists have discovered Ancient Egyptian nails that are over 5,000 years old.