Why the lowest number isn't automatically the best one
Two contractors walking the same house can come back with bids that differ by thousands of dollars simply because they measured, specified, or scoped the job differently, not because one is overcharging and the other is a bargain.
Comparing the bottom-line number before confirming the scope behind it is the single most common way homeowners end up disappointed partway through a project.
Start with what actually drives the price
A national cost guide breaks a siding bill down to size and shape of the house, which material was picked, what removal costs, and labor, calling out separately that story count moves labor on its own.[1]
Before comparing two bids' totals, confirm they're using the same measured square footage, the same material and brand, and the same assumption about how many stories are involved.[1]
Get at least three bids, on purpose
Washington's L&I and California's CSLB both tell homeowners to get multiple written bids before choosing a contractor, specifically so an unusually high or low number stands out against the others.[2],[3]
Three is a practical minimum, not a maximum. A fourth bid is worth the extra round of scheduling if the first three disagree sharply on scope or price.
Line up removal, house wrap, and trim across every bid
Removal of the old siding, new house wrap, and trim, soffit and fascia work are each sometimes included and sometimes billed separately, which can make an apparently cheaper bid actually the more expensive one once those pieces are added back in.
Asking every bidder for a line-item breakdown rather than a single lump sum is the fastest way to see where the real differences between bids actually are.
Compare the payment schedule, not just the total
A lower total paired with a large upfront deposit can carry more real risk than a slightly higher total paired with payments tied to completed work stages.
Put the deposit percentage, the number of payment stages, and the final payment trigger side by side across every bid, the same way you'd compare the dollar totals themselves.
Red flags that show up only when you compare, not in any single bid
A bid that's dramatically lower than the others, with no clear explanation anywhere in the written scope, is worth a direct follow-up question before you assume it's simply the best deal on the table.
A bid that's unusually vague on material specifics compared to its competitors is often vague on purpose, leaving room to substitute a cheaper product after the contract is signed.
Putting the comparison on one page
A simple side-by-side list, material and brand, measured square footage, removal and house-wrap inclusion, deposit amount, payment stages, and estimated timeline, turns a stack of confusing paper bids into a single page you can actually compare at a glance.
Building that comparison yourself, rather than relying on each contractor's own bid format, is what actually surfaces whether a price difference comes from scope, material, or just markup on an otherwise identical job.