Both "if" and "when" map cleanly here, just with different connectors: - If I remember → 如果我记得 / 要是我记得 - When I remember → 等我想起来 / 等我记起来 The key distinction is verb choice: 记得 = "to remember (a fact you've already memorized)" — fits "if I remember." 想起来 / 记起来 = "to recall, to have something come to mind" — fits "when I remember," because *when* implies the moment something pops back. Your example sentences: - "I'll go to the gym if I remember" → 我要是记得，就去健身房。 - "I'll text you when I remember" → 我想起来就给你发信息。 Note 记住 (which you know) means "to memorize / commit to memory" — different from both 记得 and 想起来. For your sentence, 记住 wouldn't fit. Sincerely Mark

1. “If I remember” – uncertain, just in case 1） 如果我记得 rú guǒ wǒ jì de 要是我记得 yào shi wǒ jì de 我记得的话 wǒ jì de de huà
 2）more natural for “if it occurs to me” 如果我想起来 rú guǒ wǒ xiǎng qǐ lái 要是我想起来yào shi wǒ xiǎng qǐ lái 我想起来的话wǒ xiǎng qǐ lái de huà 2. “When I remember” – more certain, assuming it will happen 等我想起来的时候 děng wǒ xiǎng qǐ lái de shí hou 3. Key difference between 记住 and 记得: 记住 = to commit to memory / to learn by heart / to not forget (action/result)
 记住我说的话 jì zhù wǒ shuō de huà Remember what I said. 记得 = to recall / to have in memory (state)
 我记得他的名字 wǒ jì de tā de míng zi I remember his name.

English version: The key is to distinguish between "记住" and "记得": "记住做某事" corresponds to "remember to do sth." For example: 1. You must remember to finish the things I arranged tomorrow. (This involves the "把" structure in Chinese. "把" itself has no actual meaning but only grammatical function, and it is indispensable here. Its structure is: 把 + noun (object) + verb (predicate) + adverbial (similar to the expression of passive voice), which is equivalent to "verb (predicate) + adverbial + noun (object)".) It is equivalent to: 2. You must remember to finish the things I arranged tomorrow. Chinese version: 我记得你已经写完了这本书. 他记得把钥匙忘在车厢里了。 English version: I remember you have already finished writing this book. He remembers leaving the key in the carriage. Hope this helps.

Learning Chinese grammar (sentence structure) is actually very simple and flexible (much more flexible than English). The main thing is that as long as the words are logically consistent, they can be expressed in any way, and there are no rules for this. Usually, if a sentence makes sense in English, it can also make sense in Chinese (but the meanings of characters, like English words, must be memorized). I am a native Chinese speaker, experiencing the hard time of learning English, and very much so understand the similar situation where a foreigner learn Chinese. Lot of Chinese teachers trying to express how to say some sentence or a Chinese character accurately and excellently , in fact, make a big mistake that the foreigner just want to solve his rub query (rather than others). Let me tell you how to solve your query: In Chinese, subordinate clauses (such as adverbial clauses of time, condition, reason, etc.) are stated first, followed by the main clause. In English, however, the main clause is usually stated first, followed by the subordinate clause. For example: Chinese: 如果我记得那件事儿，我就会去做它。(→ If I remember that thing, I will do it) English: I will do that thing if I remember (it). Chinese: 当我记住那件事时，我就会去做它。(→ When I remember that thing, I will do it) English: I will do that thing when I remember (it). In fact, both sentences are grammatically correct in both English and Chinese, and in terms of linguistic effect, their meanings are almost the same. Chinese version: 讲解 remember 汉语中的用法: 最关键是区别 “记住” 和“记得”的区别。 记住做某事= remember to do sth. 记得做某事= remember doing sth. 例如， 汉语版: 1.明天你必须记住 把 我安排的事情 做好。= （注意汉语的“把字结构”（把字本身无意义，但只有语法意义，这时把字必不可少）: 把 + 名词 （宾语）+ 动词 （谓语）+ 状语 （被动语态结构）= 动词 （谓语）+状语 + 名词（宾语）） = 2. 明天 你 必须 记住 做好 我安排的事情。 English version: The key is to distinguish between "记住" and "记得": "记住做某事" corresponds to "remember to do sth." For example: 1.明天你必须记住 把 我安排的事情 做好。