DPI, CPI and what the number means
DPI (more accurately CPI, counts per inch) is how many movement counts the sensor reports per inch of physical travel. At 800 DPI, moving the mouse one inch produces 800 counts. A high DPI gaming mouse advertising 26,000 DPI simply has headroom; it does not make the sensor more accurate at 800.
Very high DPI can actually hurt. Above roughly 3200 DPI, sensor jitter and monitor pixel density mean each count is smaller than one pixel of aim, so noise from your hand becomes visible on screen.
eDPI is the number to compare
eDPI = DPI × in-game sensitivity. It is the only fair way to compare setups across players, because 800 DPI at 0.5 sensitivity and 400 DPI at 1.0 aim identically.
Typical competitive ranges: roughly 600–1000 eDPI in CS2, 200–350 in Valorant, and 1200–2000 in Apex Legends. Start inside the range, then adjust in small steps rather than jumping between extremes.
Finding your sensitivity by cm/360
Many players prefer cm/360: how many centimetres of mouse movement it takes to turn a full circle in game. Around 30–45 cm/360 is common for tactical shooters, 20–30 cm/360 for faster movement titles.
Test it on a wide mousepad. If you run out of pad during a 180-degree turn, your sensitivity is too low for your desk, not too low in principle.
Keep it stable across games
Pick one hardware DPI — 800 is the safest default — and change only in-game sensitivity per title. Muscle memory transfers far better when the hardware layer stays constant.
Disable Windows pointer acceleration (Enhance pointer precision) and keep the Windows pointer speed on the sixth notch so no extra scaling is applied on top of your DPI.