Fishing Current and Drift Speed Calculator
Calculate river current speed and drift fishing pace in mph or km/h from GPS data or float time.
Optimize drift speed for the best lure or fly presentation.
Understanding current speed is essential for drift fishing - whether for trout with a nymph, walleye with a bottom rig, or float fishing for salmon. Speed determines how your bait drifts and how long it spends in productive water.
Float timing method: The simplest way to measure current: time how long a floating object takes to travel a known distance.
Speed = distance / time
Current speed categories:
| Speed | Description | Fishing notes |
|---|---|---|
| 0–0.5 m/s | Slow / pool | Dead-drift nymph, float fishing |
| 0.5–1.5 m/s | Moderate run | Prime trout water, swinging wet flies |
| 1.5–2.5 m/s | Fast run | Heavy tungsten nymphs, streamers |
| 2.5+ m/s | Rapid / white water | Difficult to fish effectively |
Optimal drift speed for species:
- Trout (nymph fishing): 0.3–0.8 m/s: slow enough for natural presentation
- Salmon (float fishing): 0.5–1.2 m/s
- Walleye (bottom bouncing): 0.5–1.0 m/s
- Steelhead: 0.6–1.5 m/s
Worked example: Toss a stick in at a marked rock, walk 10 metres downstream, and count it past your boots. Twelve seconds gives 10 ÷ 12 = 0.83 m/s, or 3.0 km/h. That sits in the moderate run band, inside the salmon and walleye windows and just above the ideal nymph drift.
Why speed matters for lure depth: A weighted rig sinks at a rate largely independent of the current, but the current keeps carrying it while it falls. Faster water means the rig travels further downstream before it reaches the bottom, so you have less fishable water at the depth you want. At 0.83 m/s a rig that takes three seconds to get down has already moved 2.5 metres. That is why you cast well above the lie rather than at it, and why the same weight that works in a pool skates uselessly over a fast run.
Measuring it properly: Do the float timing three times and take the middle number. One reading is worth very little: a stick catches an eddy, snags a rock, or picks up a fast tongue in the middle of the channel. Surface speed also runs roughly 10 to 20 percent faster than the average through the water column, because friction against the bed slows the bottom. If you are fishing a nymph along the gravel, the water your fly sits in is slower than the water your indicator is riding.
Boat anglers can skip the stick entirely. Drift with the engine off and read speed over ground from a GPS unit, then enter that distance and time here for the conversions and the drift check.
How we build and check this calculator
This calculator runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
SuperGlobalCalculator is independently built and maintained. See how we build and verify our calculators.