Decision Tools
The calculators answer "how much". These eight tools answer the other questions: which one, what is wrong with it, and is this quote any good?
Where our calculators tell you what double glazing should cost, the tools here help you make the decisions around the purchase. They split into two groups. Four of them narrow down what to buy, from the frame material and the window style through to the glass spec worth paying for and which material costs least across 25 years. The other four deal with the buying itself: what a fault actually is, whether to fit them yourself, whether you might qualify for help, and whether the quote in front of you is fair. Use them alongside the price ranges, not instead of them.
Material Classifier
Answer a few questions to see whether uPVC, aluminium or timber suits your home.
Style Suggester
Find the window style that fits your property and how you use the room.
Glass Spec Trade-off
A-rated is the standard, not the upgrade. See whether A+ or A++ is worth paying for in your house.
25 Year Cost Comparator
The cheapest window to buy is not always the cheapest to own. Compare the three materials across 25 years.
Window Fault Checker
Describe the fault and find out whether it is a glass, hardware, seal or frame job, and what it costs.
Supply-Only Decision Tool
Fitting adds £200 to £600 a window. See whether buying supply-only and fitting them yourself stacks up.
Grant Eligibility Checker
Answer a few questions to see whether you might qualify for a 2026 energy grant towards windows.
Quote Quality Auditor
Paste in the details of a quote and check it against the things a good install should include.
Tools versus calculators
Keep the two apart in your head. A calculator answers "how much will this cost", so reach for the uPVC window calculator when you want a number. A tool answers "should I" or "which one": whether you might qualify for help (see our grants guide for the detail behind the checker), whether a quote is fair (read how to avoid being overcharged alongside the auditor), or whether the problem you have is even a glazing fault at all, which is where the window fault checker starts. Used together they cover both the price and the decision. Neither answers the process questions that arrive after the decision, such as what deposit is normal or what a guarantee covers, and those are grouped by topic in our double glazing FAQs, so the Double Glazing FAQs index picks up where the tools stop.