DIY vs. Hiring It Out
What the project costs if you do it yourself, versus what a contractor would charge.
Width × height of the wall
What the project costs if you do it yourself, versus what a contractor would charge.
Width × height of the wall
The honest version of 'should I do this myself?' — what the materials cost if you do it, against what a contractor would charge to do it for you.
Every project type has a typical cost per square foot (or per linear foot) for materials, and a separate, higher installed cost that a contractor charges — the difference being labor, overhead, and profit. Both are shown as ranges, never a single number, because real prices vary enormously by region and material grade. Savings compare like for like: budget materials against a budget quote, high-end against high-end.
Example
Tiling a 100-square-foot bathroom floor: materials might run a few hundred dollars, while an installed quote is typically several times that. The gap is your labor — and your weekend.
Labor is typically the majority of an installed price, so doing it yourself often saves a substantial fraction of the total. The catch is that you are paying with your time, and tools you have to buy come out of the savings.
Because a single number would be a lie. Material grade, region, and job complexity move real prices enormously, and a precise-looking figure would give you false confidence.
Anything involving gas, major electrical, or structure — where a mistake is dangerous rather than merely expensive. Also anything on a deadline: professionals are fast, and that is worth paying for.