Screening decides what you may own. Purification handles what you may keep — and it is a small calculation that a great many compliant portfolios never do.
Every published screening standard tolerates a small amount of impermissible income inside an otherwise compliant company — typically up to 5% of revenue — on the reasoning that a minor, unavoidable element does not contaminate an enterprise that is fundamentally permissible. Almost every listed company earns some interest on its cash balances, and demanding zero would leave nothing investable. But that reasoning does two things and they are often confused: it permits the holding. It does not make that portion of the income lawful to keep. Purification is what closes the gap.
One multiplication. Take the income you received from the holding, and multiply it by the company's purification ratio — the share of its income that came from non-compliant sources. Screening providers publish that figure; this site also derives its own, from the issuer's filing, for every company it has a revenue line for.
purification due = dividend received × purification ratio
A holding that paid $500 in dividends over the year, in a company reporting a 2.4% purification ratio, gives $12 to be given away. Some providers publish the figure per share instead, in which case multiply by the number of shares you held when the dividend was paid rather than by the cash amount. The ratio is company-specific and changes year to year, so it is computed per holding per payment, not once for a portfolio. Where a company pays no dividend there is nothing to purify on this basis — which is the whole of the argument for the narrower position in the next section.
Work out the amount for a holding → — enter the ticker and what it paid you, and the calculator shows both conventions above, the figures from the filing that produced the ratio, and the capital-gains figure discussed in the next section. Free, and it stores nothing.
Dividends are the settled part. Whether a gain on selling the shares needs purifying is not. The narrower view holds that only income actually distributed to you can be impermissible income, since a price rise is a change in the market's valuation of an asset you lawfully owned, not a payment from the company. The broader view holds that the share price partly reflects retained impermissible earnings, so the same ratio should be applied to gains — and this becomes the operative question for growth companies that pay nothing at all, where the narrower view implies no purification is ever due. Both are held by qualified scholars. The cautious course, which several standards recommend, is to apply the ratio to gains as well; the cost of doing so is small and the cost of being wrong is not.
Purification is not sadaqah and not zakat, and the distinction is not a technicality. Zakat is an obligation on wealth you lawfully own; purification is the disposal of wealth you do not. It is therefore given without expecting reward for it — the point is to be rid of it, not to earn from it. The usual guidance is to direct it to general public benefit rather than to a mosque or to a cause where you receive standing or advantage, and it is not deductible against your zakat obligation, which remains due separately on the rest. Keeping a simple running total across the year and settling it in one payment is normal practice; nobody is expected to compute it per dividend in real time.
A symbol page here shows two non-permissible income figures and they are deliberately not merged. One is the screening provider's, passed through and labelled as theirs. The other is this site's own, computed from the issuer's filing — interest income plus realised gains on interest-bearing debt securities, over total revenue — and it is the same quotient the seven standards test against their 5% line, so the page cannot display one number and screen on another.
What remains yours is the rest of the input: which holdings, what they paid you, when, and which school's method you follow. The purification calculator supplies the ratio and the filing figures behind it and computes all three conventions; it does not tell you which one applies to you, and it is a research tool rather than a fatwa. When in doubt, consult a qualified scholar.
The vocabulary here is defined at length in the Islamic finance glossary: purification itself, non-permissible income — the figure the ratio is computed from — and sadaqah, the voluntary charity that is the usual destination for a purified amount, as distinct from obligatory zakat.
See also: Purification calculator · All articles · Is Stock Trading Halal? · Glossary · Riba, Gharar & Maysir · Screening Methodology · Not financial or religious advice.