How many windows should you replace at once?
Whole-house pricing is genuinely cheaper per window — mobilization is a real cost. But there's a point where the discount stops justifying the spend.
Yes, it is meaningfully cheaper per window to do the whole house at once. Setup, travel, and disposal are fixed costs, so a 15-window job prices lower per window than three separate 5-window jobs — often 20–30% lower on larger projects.
That said, doing the worst 6 windows now and the rest in two years is a completely legitimate strategy. Just prioritize by condition (drafts, fogged glass, rot), not just by room.
The band-compression effect:
At whole-house scale, the volume discount does something interesting: it narrows the gap between quality bands. A Long-term composite window on a massive project can price surprisingly close to what an Essential vinyl window costs on a tiny project. Same per-window logic, but you get a better product for a similar unit price.