Discount Calculator

How to calculate a discount

Every discount question reduces to three numbers: the original price, the reduction, and what you actually pay. Get any two and the third follows. For a percentage discount, multiply the original price by the percentage to get the saving, then subtract.

A jacket priced at €120 with 30% off saves you 120 x 0.30 = €36, so you pay €84. For a fixed euro reduction the arithmetic is even shorter: subtract it. The interesting cases, and the reason a discount calculator earns its place, start when reductions combine, when the shop shows you the sale price but not the original, or when a deal is framed as a bundle rather than a percentage. The calculator above handles all four, and each mode below has the thinking spelled out so you can sanity-check any price tag in Ireland or anywhere else.

Working backwards: finding the original price or the discount rate

Retail tags often show only where you landed, not where you started. Two reverse calculations recover the missing piece.

Finding the original price. If a pair of boots costs €68 after 15% off, the sale price is 85% of the original. Divide by 0.85 and the list price was €80. The general rule:

The classic mistake is adding 15% back to €68, which gives €78.20 and is wrong. Percentages do not reverse symmetrically, because the 15% was taken from the larger number, not the smaller one. The same trap appears when people try to remove VAT by subtracting 23% instead of dividing by 1.23, which is exactly why our VAT calculator has a dedicated remove function.

Finding the discount rate. When you know both prices, the percentage is the saving divided by the original. A phone marked down from €449 to €379 saves €70, and 70 / 449 = 15.6%. Knowing how to run this check matters more than it used to, because headline percentages on sale signage do not always survive contact with the arithmetic.

Stacked discounts never simply add

A common promotion pattern: 20% off everything, plus an extra 10% at the till. Most shoppers read that as 30%. It is 28%, and the gap grows with bigger numbers. Each successive discount applies to the already reduced price, so the multipliers compound rather than the percentages adding.

Take a €200 coat with 20% then 10%. The first cut brings it to €160. The second takes 10% of €160, not of €200, leaving €144. Total saving €56, which is 28%. Stack three reductions of 50%, 30% and 20% and you get 72% off, not the impossible-sounding 100%. The stacked tab above shows the true effective figure next to what the naive sum would claim, and the difference between those two lines is precisely the margin the promotion protects for the retailer. There is nothing dishonest about sequential discounting, but the framing relies on you doing the wrong addition in your head.

Multibuy deals: what 3 for 2 really costs

Bundles convert discounts into a different shape. A 3-for-2 offer where the cheapest item is free looks like a third off, and mechanically it is, but only under one condition: you genuinely wanted three items. If you came in for two and bought a third to trigger the deal, your real saving is the free item minus the extra one you would not otherwise have bought, which is usually negative.

Run the numbers on a typical case. Three items at €30, €24 and €18: the €18 item goes free, you pay €54 against a full price of €72, an effective discount of 25%, not 33%, because the free item is the cheapest by construction. The deal tab calculates the effective percentage and the average per item so you can compare a bundle against a plain percentage off, or against the unit price of buying fewer. Unit price is the great leveller for multibuys: Irish supermarkets are required to display price per kilogram or per litre on shelf labels for exactly this reason, and thirty seconds with the per-item figure regularly shows the biggest pack or bundle is not the cheapest way to buy.

The 30-day rule: when a discount is legally genuine

Since the EU Omnibus Directive was transposed into Irish law in the Consumer Rights Act 2022, a retailer announcing a price reduction must display the prior price, defined as the lowest price the product was sold at in the previous 30 days, and the discount must be measured against that. The rule exists to kill the oldest trick in sale season: raising a price for a fortnight in November so the December "50% off" is measured from a number nobody ever paid.

The Competition and Consumer Protection Commission enforces the rule in Ireland and has run compliance sweeps around Black Friday since it came in. For you as a shopper, the practical takeaway is simple: the was-price on the tag must be a real recent price, and if a discount claim looks off, the reverse tab above tells you in seconds what percentage the two printed prices actually represent. For retailers, the compliance point is equally simple: build the 30-day lookback into your pricing records before the promotion, not after the complaint.

Discounts and VAT in Ireland

Consumer prices in Ireland include VAT by law, so the discount you calculate applies to the final tag price and no VAT adjustment is needed on your side of the till. The seller's side is different: a discount reduces the consideration, so the VAT accounted for on the sale falls proportionally. A retailer selling a €123 item at 23% VAT owes Revenue €23 of it; sell the same item at 20% off for €98.40 and the VAT inside drops to €18.40. Traders reconciling promotions on a VAT3 return can pull the exact VAT content of any discounted price with the remove function on the VAT calculator, at 23%, 13.5% or the 9% rate that has applied to hospitality food since July 2026.

The psychology a calculator protects you from

Discount design is applied psychology, and knowing the standard moves is half the defence. Anchoring is the big one: the crossed-out was-price sets a reference point, and everything after it is judged as a gain from that anchor rather than as a price on its own merits. The 30-day rule polices the anchor's honesty but not its power. Charm pricing, ending at .99, works on the left-digit effect: €39.99 reads closer to €30 than to €40 in fast judgement. Urgency framing, countdown timers and last-few-remaining labels, exists to stop you doing exactly what this page recommends, which is pausing to divide two numbers. None of these techniques is illegal and none of them changes arithmetic. A discount is worth the saving on an item you would have bought anyway, at a price that beats the alternatives you checked. Everything else is theatre.

For retailers: what a discount does to your margin

The shopper's saving is the seller's margin, euro for euro, and the exchange rate is brutal. A business running a 30% gross margin that offers 10% off is not giving up a tenth of its profit; it is giving up a third, because the entire discount comes out of the margin slice. To earn the same gross profit at 10% off, that business must sell 50% more units. At 15% off it must double them. Before running a promotion, it is worth putting your own numbers through our margin calculator next to this one: the pair of tools shows both sides of the same transaction, and the volume required to pay for a discount is nearly always larger than instinct suggests. Discounts move stock, clear seasons and win price-sensitive customers, but they are a cost with a payback condition, not free marketing.

The Irish discount calendar

Discounts in Ireland cluster, and knowing the rhythm improves the odds of buying at a genuine low. The January sales remain the deepest and most genuine clearance of the year, because retailers are moving real seasonal stock that has a carrying cost. Mid-season sales in spring and early autumn clear transitional ranges at shallower cuts. Black Friday and Cyber Monday arrived from the US as import events and now run for most of November in practice; they are also the period the CCPC watches most closely for prior-price compliance, precisely because the volume of claimed reductions is at its annual peak. Summer sales bridge the gap in fashion and homewares. Outside the calendar, the steadiest discounts are structural rather than seasonal: end-of-line clearances, floor models, cosmetic-damage stock and the negotiated discount that appears surprisingly often when a customer simply asks. A price tracker or a screenshot habit turns any of these from a claim into a checkable fact, and the reverse tab above does the checking.

Trade and settlement discounts for businesses

Consumer promotions get the attention, but two other discount species run through business life. A trade discount is a standing reduction from a list price for a class of buyer, a plumber's counter price against the retail tag, and it simply defines the real price: VAT and margin are both calculated on the discounted figure from the start. A settlement discount, a few percent off for paying an invoice within, say, ten days, is different in kind: it is the price of money, not of goods. A 2% discount for paying 20 days early is an annualised return of roughly 36%, which is why finance teams treat missed settlement discounts as expensive borrowing. The VAT treatment matters too: where a settlement discount is offered, Irish practice requires the VAT position to follow what is actually paid, so credit notes or invoice wording have to be handled correctly, and the VAT3 guide covers where adjustments land. For the arithmetic on either species, the percent-off tab above works unchanged: a discount is a discount, whoever is receiving it.

A short checklist before any discounted purchase

Everything on this page compresses to five questions. Would I buy this at the sale price if there were no crossed-out number beside it? Is the was-price a real recent price, which the 30-day rule says it must be? Does the effective percentage, calculated rather than claimed, match the sign? For a multibuy, do I want the quantity that triggers the deal, and what is the per-item cost against buying fewer? And is the same item cheaper elsewhere today at plain price, which a sixty-second search answers? A discount that survives all five is a good purchase. One that fails the first question was never a saving at all, because money spent on an unwanted item at 40% off is not 40% saved, it is 60% wasted. The calculator handles the arithmetic in the middle three; the first and last are yours.