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1. The price and the offers
Ticket price
$
How many you're buying
Offers, applied in this order
🚚
2. The rest of it
Delivery
$
Free delivery over
$
Tax added at the till
%
Best price somewhere else
$
🧾Delivery and tax are where a good discount
quietly becomes an average one. Both are counted here, and the comparison price is
compared like for like.
🏷️
3. What it actually is
🧮
Why stacked discounts are always smaller than they sound
- Percentages off don't add up — they multiply. Take 40% off and you're paying 60% of the price. Take another 20% off that and you're paying 80% of the 60%, which is 48%. So 40 and 20 is 52% off, not 60. The gap gets wider the bigger the numbers: 50 and 50 is 75% off, not free.
- The order doesn't matter for percentages, but it does for money-off. Two percentage discounts give the same answer either way round. A "$20 off" voucher is worth more when it comes off a bigger number — so a shop that applies the percentage first and the voucher second is giving you less than one that does it the other way. The table shows which order yours is in.
- Buy-one-get-one-free is 50% off, and only if you wanted two. Three-for-two is 33% off. Buy-one-get-one-half-price is 25% off. Each of those is the real figure per item, and each depends entirely on whether the extra one is something you'd have bought anyway.
- Delivery undoes small discounts completely. 20% off a $30 item is $6; a $5.99 delivery charge takes almost all of it back. That's why the panel gives you a single final number rather than a percentage to feel good about.
- A "free delivery over $50" line changes the maths in the other direction. Buying a second thing you did want can genuinely cost less than buying one and paying postage — and buying a second thing you didn't want never does. The tool tells you which side of that line you're on and leaves the wanting to you.
- The one thing no calculator can check is the "was" price. Every number here is arithmetic on figures you typed, and arithmetic is certain. Whether the item was ever genuinely sold at the higher price is not something a tool can know — the honest advice is to check what it cost a month ago rather than what the label says it used to cost.
- And a discount on something you weren't going to buy is not a saving. It's a purchase. The panel says what you'll pay, not what you'll save, for exactly that reason.