The 60-second difference
A full-size reciprocating saw (Sawzall is the Milwaukee brand name that became generic) has a long body, a 1-1/8" to 1-1/4" blade stroke, and enough mass to push through nail-embedded wood, cast iron pipe, and tree roots. It's a demolition tool.
A Hackzall (Milwaukee's name for the one-handed compact reciprocating saw) shrinks the body to pistol-grip size, drops the stroke to about 3/4", and trades raw power for the ability to work one-handed in cabinets, under sinks, and on ladders. It's a plumbing and HVAC tool that happens to cut wood.
The three jobs where each wins
Full-size wins on: cutting through a 2x4 with nails in one pass, pruning a 3-inch branch, and any job where you can plant both hands and lean in. If you're doing a bathroom gut or deck removal, this is the saw.
Hackzall wins on: cutting a PVC pipe inside a cabinet, trimming a bolt flush in a tight corner, and working overhead without arm fatigue. If your project list includes plumbing, HVAC, or automotive work, the compact body earns its keep.
The overlap zone — cutting drywall, trimming small branches, general pruning — either saw handles. The mistake is buying a full-size saw for a job that needs one hand, or a Hackzall for demolition.
What the specs actually mean
Stroke length: longer stroke (1-1/8"+) removes more material per pass. For demolition, this is the number that matters. For tight work, a shorter stroke is actually better — less blade whip in confined spaces.
SPM (strokes per minute): 2,800–3,000 is standard. Variable speed triggers matter more than the top number — you want to slow down for metal and plastic.
Corded vs. cordless: corded is cheaper and never dies mid-cut, but the jobs that justify a reciprocating saw are often on ladders, in crawl spaces, or outdoors where a cord is a hazard. If you own a 20V battery platform, a bare cordless tool is the cheapest path in.
Blades: the part that actually cuts
The saw is just a motor; the blade decides what it cuts. Wood blades have 6–10 TPI (teeth per inch), metal blades have 18–24 TPI, and demolition blades are thick with variable pitch for nail-embedded wood. A 5-pack of quality blades costs $15 and outlasts the cheap 20-pack that came with the saw.
For a first purchase, buy a wood blade, a metal blade, and a demolition blade. That covers 95% of household reciprocating saw work.
Common questions
Can a Hackzall cut through a 2x4?
Yes, but slowly — the shorter stroke means more passes. For occasional 2x4 work it works; for repeated demolition, a full-size saw is the right tool.
Is a reciprocating saw worth it for a homeowner?
If you do plumbing, HVAC, or automotive work, yes. For general household repairs, a jigsaw or circular saw covers most cuts better. The reciprocating saw is a specialist, not a generalist.
What size reciprocating saw blade do I need?
Match the blade to the material, not the saw. 6-inch blades for wood and general use, 9–12 inch for demolition and thick branches, 4-inch metal blades for pipe. Most saws accept any standard 1/2" shank blade.