DeWalt DCS578N Review – UK Tried & Tested

When this saw was tested against the best cordless circular saws on the market, it took the full-depth result. Blade buried in four sheets of OSB, 20 pounds of pull on the handle, and it came through in 7.7 seconds. Nothing else in the group came close. That number is the reason to buy it.

The DCS578N runs on DeWalt’s 54V XR FlexVolt system, with a 190mm blade and 67mm maximum cutting depth at 90 degrees. At 5,800rpm no-load and a peak output of 2,456 watts, it is the most powerful cordless sidewinder in the DeWalt range. Where other cordless saws run out of depth capacity on 3x framing lumber or stacked ply, the DCS578N goes through both in a single pass.

Overview and first impressions

The FlexVolt battery auto-switches voltage depending on the tool: 54 volts in FlexVolt tools, 18 volts in standard XR tools. The same battery that powers this saw at full 54V capacity slots into any existing 18V XR drill, combi, jigsaw, or driver and runs normally at 18V. No setting to change. No adapter. The switching is in the battery, not the tool. For a professional already on DeWalt 18V XR, adding a FlexVolt battery does not start a new system. It extends the existing one. That battery then becomes the highest-capacity option in the whole collection, available to every XR tool in the kit.

The bevel adjustment runs to 57 degrees with positive stops at 22.5 and 45 degrees. Depth and bevel levers are easy to adjust. A fold-out rafter hook is built in, which allows hanging the saw when both hands are needed to position timber. The AirLock dust port uses a bayonet fitting rather than a friction connection. A standard dust extraction hose can fall off a friction port during the vibration of cutting. AirLock locks and stays locked. For site work in occupied buildings or anywhere dust control matters, this is a practical advantage over generic port fittings. The dust extraction port is included in the box. The LED work light illuminates the cut line without casting a shadow across it, and the dust blower keeps the line visible during cutting.

Specifications and scores

How it performed in our tests

At 3.6kg body-only the DCS578N reads as manageable. But body-only weight on a FlexVolt tool is not the weight you use. The FlexVolt 9Ah battery is substantially heavier than a standard 18V 5Ah battery. Professional testing with the 9Ah battery put the complete working weight at 11.5 pounds (approximately 5.2kg), placing it 11th heaviest in a group of professional cordless saws. The front handle design carries some of this weight well. The angle and distance from the rear handle distribute the load in a way that feels better than the numbers suggest. But it is heavy, and on a long day of site work that weight accumulates.

The DCS578N base plate creates more resistance against the workpiece than most other professional saws in the same class. On the maximum-demand full-depth test, this does not matter because the power overwhelms it. On a standard two-sheet OSB rip, it placed 9th in the same group. The saw that wins the hardest test takes a midfield position on an ordinary one. The reason is shoe friction. You are pushing harder through every cut. Over a full day, that effort adds up. Waxing the base plate helps. A better blade helps. It does not go away entirely.

The sightlines are good rather than exceptional. The upper blade guard extends slightly further than ideal, and during bevel cuts it partially blocks the 0 and 45 degree markings on the shoe, requiring a lean to the left. On standard crosscuts this is not a problem. On compound bevel and mitre cuts the guard hangs up very slightly at the start, which pulls fractionally left before correcting. Both the 90 and 45 degree notches align accurately with the blade on quality blades, which makes notch-tracking reliable.

Tracking itself is excellent. No drift left or right from the front handle. The handle position and angle were the most comfortable of the professional saws tested. Despite the weight, the saw feels balanced in hand rather than nose-heavy.

Battery system and runtime

A standard 18V XR battery fits the DCS578N and the saw will run, but at 18V only. For the full 54V performance, specifically the 47% power improvement over the predecessor model, a FlexVolt battery is needed. The 9Ah pairing is what DeWalt’s performance claims are based on. With smaller FlexVolt packs the power improvement is present but less dramatic.

3x framing lumber is approximately 63mm thick. Most 18V cordless saws max out at 60 to 64mm and cannot reliably get through 3x material in one pass. The DCS578N at 67mm clears it. Three sheets of 3/4 inch plywood stacked comes to roughly 57mm, tight or impossible for many 18V saws at depth, straightforward for the DCS578N. At 45 degrees the saw delivers 49mm, where 18V saws typically drop to 42mm or less. For structural carpenters and framing professionals working with larger timber in volume, the extra depth capacity is the practical reason to choose this saw rather than an 18V alternative. Not because the numbers look better. Because you stop having to flip boards or make two passes.

Performance and limitations

The included rip fence has attracted one notable complaint from UK site users: it arrived out of square. This is an accessory quality issue rather than a problem with the saw itself, but for rip cutting where the fence is the reference, it means checking and adjusting the fence before trusting any cut made against it.

What’s in the box: the saw body, a 190mm 24-tooth TCT blade with a 30mm bore, a blade wrench, the rip fence, and the dust extraction port. No battery, no charger, no case. The saw is sold body-only because DeWalt expects most buyers to already own XR batteries and chargers. The FlexVolt battery is the additional purchase if one is not already in the collection. The 3-year warranty applies on registration with MyDeWALT within four weeks.

Final verdict

The DCS578N is not the answer for every circular saw job. It is too heavy for sustained overhead or restricted-access cutting. The shoe friction makes ordinary cuts feel harder work than they should. It costs more than 18V alternatives. For a finish carpenter, a furniture maker, or anyone whose work is primarily crosscuts and joinery, a lighter saw with lower friction will serve better. For a structural carpenter, a framing professional, or anyone on a site where 67mm depth and 2,456 watts of cordless power are genuinely needed in the course of a normal day, there is currently no faster cordless sidewinder available.