Method
How we compare HP 305 cartridges
The rules below aren't intentions: they're in the code that builds every page.
Content updated:
Which retailers
We currently compare: TonerGiant, CartridgeMonkey, The Cartridge Centre, HP Store, Argos, Cartridge Save, Amazon.co.uk. A retailer is here because it's useful to someone buying HP 305 — not because it pays us. Retailers without an affiliate programme belong here just as much.
Two well-known UK retailers are missing for now: when we checked on 23 September 2026, Currys showed a "We'll be back soon" page and Cartridge People showed an automated bot check, so we couldn't read a price from either. We don't get around bot checks.
How a price gets onto the site
- Every price was read from the retailer's exact product page and carries the date it was checked.
- A price older than 14 days is no longer shown as a number; the retailer stays listed with "price at retailer".
- Delivery times and stock go out of date faster: after 2 days we stop repeating them.
- We only show Amazon prices from Amazon's own Product Advertising API. Until that's connected, we link to the exact Amazon listing without an amount.
Ranking
Retailers with a current price come first, lowest to highest. If delivery costs are known for every priced retailer, we rank by delivered total; otherwise by product price. On a tie, the most recently checked price comes first, then a fixed editorial order. Commission is never an input.
Unknown delivery is never shown as "free". We use each shop's published policy: HP Store UK delivers free to UK mainland, Argos charges £4.95 for small-item home delivery (free over £100) and Cartridge Save charges £3.95 under £30. One shop's product data claimed £0 delivery where its delivery page says otherwise; we follow the delivery page.
Cost per page
Cost per page = product price ÷ HP's stated yield (ISO/IEC 24711), per colour position. We never add black and tri-colour into one figure: they don't run out at the same time. Delivery isn't included in the cost per page.
We compare an alternative with the same composition in original HP cartridges and show the pages per colour separately. An alternative's yield is the seller's own figure, not tested by us. If a seller gives contradictory yields, we leave the product out of the comparison.
What we don't do
- No made-up prices, reviews, star ratings, stock levels or test results.
- No "best buy" based on a single criterion, no countdown timers or scarcity badges.
- No calling an alternative "as good as the original" without our own testing.
See also the affiliate disclosure.