How we rank deals
How we rank deals
Every ranked list on SpoolDeal is worked out from our own price checks, the same way for every visitor. This page lists what decides the order and how much each thing counts.
Independent
- No brand, seller or retailer pays for a place in any list or sort. We earn a commission when you buy through our links, at the same rate whatever we rank first.
- A sponsored card, when one is shown in a grid, is labelled Sponsored and sits outside the ranking.
- We list Amazon UK and Eryone UK. A listing from another shop is not in these lists.
What “usual price” means
The usual price is the middle of the prices we recorded for that listing over the last 90 days, each weighted by how long it lasted (a time-weighted median). It only counts once we have 21 days of history; before that a listing makes no “below usual” claim. We never use a seller's own “was” price.
Best deals right now
The first row on the homepage. Recalculated every 2 hours.
Filament in stock on Amazon UK and Eryone UK that is at least 5% below its usual price, at its lowest price in 90 days, or in a live Amazon lightning deal. A listing with no usual price yet can still qualify when it is at least 10% below the price at our previous check.
| What counts | How much |
|---|---|
| How far below its usual price | 1 point per 1% below (20% below scores 20). The biggest factor. |
| Lowest price in 90 days | +5 points |
| Live Amazon lightning deal | +5 points |
| Price per kg against other spools of the same material | +1 point for every 10% cheaper per kg than the material's median, up to +10; −1 for every 10% dearer, down to -5. |
| How many members favourited it | 2 × ln(1 + favourites), at most +6 (1 favourite ≈ +1.4, 5 ≈ +3.6, 19 or more = +6). |
| No usual price yet (under 21 days of history) | Instead of the points above for price history: 0.3 points per 1% below our previous check, minus 20, so these rank below listings with history. |
| AliExpress listing not known to be from the brand's own store | −15 points |
- Colours of the same spool at the same price count once (one per brand, material, size and price).
- At most two listings per brand, then the top 12.
- Ties go to the same fixed order every time.
Cheapest per kg
The second row on the homepage. Recalculated every 2 hours.
Filament in stock on Amazon UK and Eryone UK at 4 or more per kg (a lower figure is treated as a listing error).
| What counts | How much |
|---|---|
| Price per kg | The only factor: lowest first. |
| AliExpress listing not known to be from the brand's own store | Counted 25% dearer per kg. |
- Colours of the same spool at the same price count once.
- At most two listings per brand, then the top 12.
Today's deal
The large card at the top of the homepage.
| What counts | How much |
|---|---|
| Taken from Best deals right now | Always one of that row's listings. |
| From the brand's own store | First: an AliExpress listing not known to be the brand's own only leads when nothing else qualifies. |
| Dropped in the last 3 days to at least 10% below its usual price | Next (shown as “Today's biggest drop”). |
| How far below its usual price | Then the furthest below, then the row's order. |
- The printer and accessory cards behind it are the top of the printer and accessory rankings below.
Deal pages
The pages under Deals, such as Price drops today, Biggest discounts and Under £10/kg.
| What counts | How much |
|---|---|
| How far below its usual price | Price drops today (dropped in the last 36 hours), Biggest discounts (10% or more), Black Friday and Prime Day: furthest below first. |
| Price per kg | At their lowest price, Under £10/kg and Under £15/kg: lowest per kg first. |
| When the deal ends | Lightning deals: ending soonest first. |
| AliExpress listing not known to be from the brand's own store | −15 points off its % below usual, or counted 25% dearer per kg. |
- Black Friday and Prime Day open with "The gems": the listings at least 25% below their usual price, or 15% below it at the lowest price we've ever tracked, furthest below first and two per brand. The "Gems only" filter on deal pages keeps every gem.
Printers and accessories
Accessory pages, /printers, the accessory rows and the hero's printer and accessory cards.
| What counts | How much |
|---|---|
| How far below its usual price | First: furthest below first; listings without a usual price after those with one. |
| Lowest price in 90 days | Next |
| How many members favourited it | Next |
| Price | Then cheapest first |
- A brand's fourth and later listings come after every brand's first three.
Sort options
Choosing a sort replaces the ranking with a single order:
- Best deals first
- Deal pages: the page's ranking above.
- % Discount
- The change since our previous check of the price, biggest drop first; listings without a drop after those with one, newest first.
- Popular
- How many members favourited it, most first.
- Price (Low to High / High to Low)
- Price per kg on the homepage grid. Elsewhere bundles compare per kg and single spools by spool price.
- Date Reduced / Date Increased
- Only listings whose latest price change was a drop (or a rise), most recent first.
- Alphabetical
- By the listing's title.
- Best deal (accessories)
- The accessory ranking above. Price and Newest sort by price or by when we added the listing.