DeWalt 850 Atomic PowerStack vs Makita GDT01 40V Max XGT: Which Impact Driver Wins?

Introduction

Two impact drivers sat side by side on the workbench for this comparison: the new DeWalt 850 Atomic running the brand’s PowerStack battery technology, and Makita’s GDT01 40V Max XGT, the flagship of Makita’s top-of-the-line cordless platform. On paper they should not even be close. One runs a compact 20V-class battery, the other a full 40V Max pack. In practice, the results were far tighter than the spec sheets suggest.

The Fastening Tests

The first round used 5/8-inch drywall fasteners driven into two-by-fours, and the result was dead even. To force a separation, the test escalated to three-inch drywall screws driven three inches deep into wood, one of the highest-torque fasteners an impact driver can realistically drive, with both tools on top speed. Even there, the gap stayed remarkably small, with several rounds finishing within a fraction of a second of each other.

Running three screws in a row also showed off how wieldable both tools are. The Makita is the heftier of the two, which is no surprise for a 40V platform, but the DeWalt’s compact size never became a disadvantage in the fastening work.

Battery Size Versus Runtime

This is where the numbers get interesting. The Makita 40V Max pack is rated at 2.5 amp hours, while the DeWalt PowerStack is a 1.7 amp hour pack on a 20V-class platform. Because the DeWalt runs at a higher effective voltage than a standard 20V battery, the fair comparison is different: the PowerStack pack works out to roughly 30.6 watt hours in this configuration, where an equivalent standard 5 amp hour 20V battery would deliver about 100 watt hours. The point of the test was to see whether the small PowerStack pack would sag under load despite its size.

It did not sag noticeably. The PowerStack battery delivered strong current in the initial fastening rounds and kept pace with the much larger Makita pack, which was fully charged for every test alongside the DeWalt.

Controls and Speed Settings

One practical difference emerged around speed control. The Makita GDT01 has LED indicator lights for its speed settings, making it easy to confirm which mode you are in at a glance. The DeWalt 850 uses what is best described as an analog mechanical switch instead, with no LED indicators for speed selection.

It is a small detail, but anyone who switches between precision driving and full-power work several times a day will notice the difference in daily use.

Drilling Performance

The final test moved from fastening to boring holes, using one-inch self-feed speed bits in brand new two-by-four lumber with no knots, so neither tool had an excuse. The protocol called for just enough pressure to start the bit self-feeding, then letting the tool do the work with hands kept clear of downward force.

Both tools bored fast, clean holes, and swapping sides to rule out any advantage confirmed how evenly matched they are. The Makita’s extra weight does not translate into a drilling win; the compact DeWalt kept up throughout.

Overall Buying Advice

The verdict from this head-to-head came down clearly on one side: the DeWalt 850 with the PowerStack battery is the pick, and its performance against a 40V competitor is genuinely impressive given how much smaller and lighter the whole package is. That said, neither tool is a wrong answer. If you are already in, or able to buy into, the Makita 40V Max XGT platform, the GDT01 is a strong impact driver with plenty of power, features, and functions, and it will not disappoint. The deciding factor is usually the battery platform you are already committed to, since the tools themselves are closer than the voltage difference implies.

Conclusion

The DeWalt 850 Atomic PowerStack proved that a compact battery can hang with a full 40V flagship in real fastening and drilling work, and it takes the win here thanks to that performance in a smaller, lighter package. The Makita GDT01 remains a top-tier option for anyone invested in the 40V Max XGT system. Choose based on your platform, and you will be happy with either.