This is also a complicated for people who follow other books instead of the Book of Allah. But it is very clear for people, who wish to follow Al-Quran, regardless if they take the term ZAKAT as charity too
The Term [ ZAKAT] from the language point of view can also simply mean purification see them verses below
2:129/151/174/232 - 3:77 - 18:19/74/81 - 19:13/19 - 20:76 - 23:4 - 35:18 – 53:32 - 87:14 - 91:9 - 24:21/28/30 - 79:18
And this why all Messenger/Prophet came to [UZAKIHIM] Purify people. Also we cannot find any verse which say pay ZAKAT to such & such people.
The term [SADAKA] from it’s root-wood has several meaning such as [fulfil/ truthful/ honourable] However Allah has used the term [YUNFIQUNA/They spend] to indicate as a charity too.
THREE IMPORTANT VERSES TO UNDERSTAND THE TOPIC
THE QURAN 2:219
They ask YOU concerning wine and gambling. Say: "In them is great sin, and some profit for men; but the sin is greater than the profit.
And they ask YOU what they should to SPEND. Say: "That which is BEYOND your NEEDS." Thus Allah makes clear to you HIS Ayat/Verse [laws] in order that you may give thought
THE QURAN 2:215
They ask you what they should SPEND
Say: WHATEVER you spend of good
For Parents and Nearest [neighboured/relative] and Orphans and Al-Masâkin/The Poor and the travellers [son of the road]
and whatever you do of good indeed Allah knows it well.
THE QURAN 9:60
Indeed whatever the SADAKAT is for the POOR & the NEEDY & the COLLECTOR & The ones INCLAINED their hearts & freeing necks [slave] & for those in DEBT & for to the way of ALLAH. & the TRAVELLER [son of the road] (this is the) an OBLIGATION imposed by Allah & Allah is All-Knower, All-Wise
Above three verses clearly do not set any fix amount on sadka in fact it’s leave up to the believers to decide, what we can spend by assessing the situation of the needier & what we can afford or whatever beyond our NEEDS And surely more we spend more better for us. But we have to spend something since it is an obligation .
THE VERSES THAT TALK ABOUT SADAKA
[2:196] inform us that one of the type of compensation regarding [Hajj issues] that we must feeding poor people.
[2:263] Kind saying hiding others Faults it is better then charity followed by injury.
[2:264] Believer should [avoid nullify their charity ] not show of when giving the charity & must avoid hurting the receiver to get full benefit of the charity
[2:271] Giving SADAKA openly is good but if do it secretly to the needy [sincerely sake of Allah] that more better, & that will be wipe out some bad deed.
[2:276] Allah descries the Usury from blessing & increase the deed of Charity. the believer will have their reward with their Lord.
[2:177] we must spend in love of Allah toward KIN /ORPHANS /NEEDY/ TRAVELAR [son of road/no house to live] RANSOM to free SLAVES .
[2:219] They ask How much they are to spend; SAY: "What is beyond your needs.
[4:4] On marriage we need to give women [DOWER] gift which also class as SADAKAK but if they forgive any part then no sin for as to enjoys such assets.
[4:114]No goods on Most secret talks except arrangement to give SADAKA or Justice or conciliation between people and if they do this to sake of Allah. They will receive highest reward from Allah for such action.
[6:142] It is Allah who produces everything in gardens so eat & pay the DUE on the day of its harvest, and Don’t be extravagance.
[8:36] The unbelievers spend their wealth to hinder people away from the path of Allah
[8:41]Whatever the believer gain [obtain of spoils], that one-fifth shall go to Allah & Messenger, and the relatives, and the orphans, and the poor, and the traveller [son of road].
[9:79] Those [hypocrites] criticize to believers who give more & ridicule the poor believers for giving too little
[9:103] The Messenger/Prophet accepted some gift from the believer In order to cleanse and purify them [to make amends] and made pray for them
[58:12] Believer are ask to give [SADAKA] something when consult the Messenger/Prophet [But if they find nothing to give the Allah Most Merciful] that is best for them.
[ 59:7-8 ] this indicate that, [the person of the category] should NOT complain if they get less or more. The Messenger /Prophet will decide whom to give HOW much SADAKA. The messenger may conceder to give MORE to the indigent MUHAJIRS those who were expelled from their homes/their property since they in MORE needs
[70:24/25]And those in whose wealth is a recognised right  For the [needy] who asks and him who is prevented [for some reason from asking]
12 CATEGORY FOR TO DISTRIBUTE SADAKA
[To propagate the Message of Allah The Quran]
[At the time of Messenger since his full time duty/job establish Allah’s Deen/Law]
[simply meaning any of our relative specially whom in need]
[Any orphan who’s in desperate need Muslim or None Muslim]
[Any poor who is in desperate need Muslim or None Muslim]
7 TRAVELLER[son of road]
[Any traveller who is in desperate need Muslim or None Muslim]
[Those who enter Islam & they Lost everything due to Islam or expel]
[Collector should not take a % from the actual SADAKA what he collected. But he will be given a wages by the payer from the SADAKA to do the work in trust]
10.MUHAJIR [Heart Reconciled]
[Those who you think will leave ISLAM because of poverty. sometime we see the NGO is working and giving charity to establish their manmade religion]
11 CAPTIVE / SLAVE
[Sadaka can given to release any slave Muslim or None Muslim because human should NOT be a slave of another human]
12 THOSE WHOM IN DEBT
[Someone in great difficulty because of DEBT which could lead him to wrong doing ]
The so-called Scholar whom wish to STEAL ordinary people money, they made so many rule such as 1/40 of Cash & Gold/Silver or on certain animal 1/10 Which is nothing but just confused calculation. They also given so many type of name such as [ZAKAT MAL /ZAKAT FITRA/ KHUMS].All of these has NO base in the Quran, it is nothing but a manmade insertion in Islam.
There is so many culprit trying to benefit from SADAKA. Them culprit sometime give evidence from Quran by twisting verse or taking verse out of context. And the best one among them is the IIPC sect whom change the meaning of the term [ZAKAT to JUSTIFICATION] which is just pure LIE.
They also propagate, the SADAKA is 20% they twist [Verse 8:41] to accomplish their needs. They also have fake theory on subject/term [Usury] which they think it is the unpaid [ZAKAT / SADAKA].
However I haven’t got time to waste on such culprit & I leave them deceiver for Allah to deal with them. And my sincere request for ordinary people is that DON’T get CON by anyone, Neither DON’T try to cheat anyone creation of Allah.
Moreover It’s always best to give Sadaka DIRECTLY to any of them mention category. And don’t forget most of them so-called Sadaka collector organisation, don’t pass over the full Sadaka. Unfortunately some of them deceiver keep large amount of SADAKA for themselves and they validate it by saying it is their expenditure. Lastly I finish this with beautiful verse of Al-Quran [ Allah knows best ]
The Quran 2:173
Those who conceal Allah's revelations in the Book and purchase for them a miserable profit They swallow into themselves naught but Fire; Allah will not address them on the Day of Resurrection, nor purify them; grievous will be their penalty .