The phrase "about the same size as a" is correct and usable in written English.
You can use it when comparing the size of one object to another in a descriptive context.
Example: "The new smartphone is about the same size as a credit card, making it very portable."
Alternatives: "approximately the same size as a" or "roughly the same size as a".
In case you don't know what one is, a battleball is a medium sized ball (about the same size as a soccer ball) on a string that you can kick or just pay with.
He had in his hand a little piece of paper about the same size as a dollar bill.
That makes the Hywind about the same size as a large traditional offshore turbine delivering comparable power.
In the case of Harrods, its latest variant is produced by the Peruvian uchunari, a long-snouted Andean animal about the same size as a luwak.
About the same size as a Scrabble tile, it houses a series of micro-reservoirs covered by an ultra-thin titanium and platinum seal.
The keyboard, which is about the same size as a Palm hand-held device when it is folded, weighs 4.2 ounces and is powered by one AAA battery.
Because they are so tiny about the same size as a protein molecule or a short sequence of DNA they can be used as probes to track reactions in living cells.These tiny light tags are helping researchers in drug discovery, medical diagnostics and in the analysis of gene expression.
What's different about the Freelander is that, although it's somewhat smaller than other Land Rover vehicles about the same size as a Toyota RAV4 inside, but with a bit less cargo capacity it offers the first blend of very serious off-road capability (like the new Jeep Liberty) and strong luxury (like the Lexus RX300) in a single package.
Blow it up to about around the same size as your head and tie it.
These are about the same size as the Earth, but with a million times the mass.
They are about the same size as the Borzoi, but have a shorter coat.
