Regardless of whether: 〜にかかわらず

〜にかかわらず means “regardless of, irrespective of, whether… or not”: the condition before it has no influence on what follows. You put it after a noun that varies (天候, 年齢, 結果), after a pair of opposites (勝ち負け, 好き嫌い) or after an alternative 〜か〜ないか. Written register: regulations, notices, formal emails. Careful: にもかかわらず, with も, means “despite”.

• 天候にかかわらず、イベントは予定どおり行います。てんこうにかかわらず、いべんとはよていどおりおこないます。Whatever the weather, the event will go ahead as planned.
• 参加するかしないかにかかわらず、メールで返事をください。さんかするかしないかにかかわらず、めーるでへんじをください。Whether or not you're taking part, please reply by email.
• 経験の有無にかかわらず、誰でも応募できます。けいけんのうむにかかわらず、だれでもおうぼできます。Anyone can apply, with or without experience.
• 好き嫌いにかかわらず、この仕事はやらなければならない。すききらいにかかわらず、このしごとはやらなければならない。Whether you like it or not, this job has to be done.

かかわる (関わる) is “to be connected with, to concern”. にかかわらず is “unconnected with X”: X has no bearing on what follows. You use it when several cases are possible (rain or shine, yes or no, a lot or a little) to announce that the decision or rule stays the same in every case.

The tone is written and official: regulations, registration terms, notices, business emails. The expression is usually written in hiragana.

• 金額にかかわらず、カードでお支払いいただけます。きんがくにかかわらず、かーどでおしはらいいただけます。You can pay by card, whatever the amount.
• 勝ち負けにかかわらず、最後まで全力でプレーしよう。かちまけにかかわらず、さいごまでぜんりょくでぷれーしよう。Win or lose, let's play all out to the end.

What all the constructions have in common: what comes before contains several possibilities. Either a noun that varies by nature, or a pair of opposites, or an explicit alternative.

• 量の多い少ないにかかわらず、送料は五百円です。りょうのおおいすくないにかかわらず、そうりょうはごひゃくえんです。Whether the order is big or small, shipping is 500 yen.
• 行く行かないにかかわらず、金曜日までに知らせてください。いくいかないにかかわらず、きんようびまでにしらせてください。Whether you're going or not, let me know by Friday.

A single syllable, も, changes everything. にもかかわらず (line 9) means “despite, even though”: you start from one real fact, and what follows is unexpected (大雨にもかかわらず、試合は行われた: it rained, and yet the match went ahead). にかかわらず considers several possible cases and says none of them matters.

A simple guide: if you can translate it as “whether… or not” or “whatever”, it's にかかわらず; if it's “despite” or “even though”, it's にもかかわらず.

• 大雨にもかかわらず、多くの人が集まった。おおあめにもかかわらず、おおくのひとがあつまった。Despite the heavy rain, lots of people turned up.
• 雨が降るかどうかにかかわらず、傘を持っていこう。あめがふるかどうかにかかわらず、かさをもっていこう。Whether it rains or not, let's take an umbrella.

を問わず (previous point) only attaches to a noun and sounds very administrative (男女を問わず). にかかわらず also accepts clauses (〜か〜ないか). In conversation, に関係なく is preferred, as it sounds more natural.

• 男女を問わず、誰でも応募できます。だんじょをとわず、だれでもおうぼできます。Men and women alike may apply.
• 好きか嫌いかに関係なく、野菜も食べなさい。すきかきらいかにかんけいなく、やさいもたべなさい。Whether you like them or not, eat your vegetables too.