Chinese symbol for strength
The Chinese symbol for strength, in the sense of inner strength, is 心力 (xīn lì), the same in simplified and traditional writing. 力量, the word most translators give, reads to Chinese speakers as physical force. For the strength to endure, choose 坚韧 (traditional 堅韌, jiān rèn). Duane checked this reading. The picture is a sample stencil, not a design made for your own words, but feel free to download it if it suits your needs.
If you mean brave, see Chinese symbol for courage.
Characters
Simplified is mainly used in mainland China and Singapore. Traditional is used in Taiwan, Hong Kong, and classic Chinese calligraphy, including Ou style (歐體). Readers in all these places generally recognize either.
For this word, the simplified and traditional forms look the same.

Simplified and traditional look the same here.
Classic uses 汇文正楷 (Huiwen Zhengkai). It is a modern font copied from 汉文正楷 (Hanwen Zhengkai), a regular script (楷书) metal type used to print books and papers in China in the early 1900s. It was copied from a printed sample sheet of the small size of that type. The slightly rough edges and small nicks are marks of that old printing, not mistakes. Smooth uses LXGW WenKai, a newer font with clean edges. Prefer smoother strokes? Choose Smooth, or just ask.
This sample uses 汇文正楷 (Classic) or LXGW WenKai (Smooth), both regular script (楷书) fonts. Both are in the same brush-style family as the 欧体 Duane has practiced since childhood, but neither is 欧体 and neither is his own brush writing. Want it closer to classic 欧体 calligraphy? Choose Hand-brushed by Duane in the form.
Meaning
心力 is inner strength: the force of a person's mind and heart. Simplified and traditional look the same. If you mean strength to endure, the pair is 坚韧 (traditional 堅韌, jiān rèn), steady toughness that keeps going.
Common mistakes
力量 is the answer most translators and generators give, but on its own it reads to Chinese speakers as physical force, like lifting power. It only takes a broader sense in context, for example 團結就是力量 (unity is strength), where it means the collective force that comes from unity. A lone 力 is just force, and it looks unfinished as a word.
Also check the final stencil before you ink: a flipped (mirrored) character, a look-alike with one stroke changed, or a whole English sentence put through a machine translator are the mistakes Chinese readers spot first. See how to avoid a wrong Chinese tattoo.
Before you tattoo this
Say whether you mean inner strength or the strength to endure. If you mean brave, that is courage, not this word.
Want this in your own words or name? Tell Duane the meaning you're after.
Checked by Duane, who grew up in China and lives in Ottawa. About Duane. Reviewed .