How the DartFit algorithm picks your dart

Step 1: measuring your hand

Your phone recognises 21 points on your hand (MediaPipe, running on your device). A bank card is always 85.6 × 53.98 mm (ISO/IEC 7810 ID-1), so it works as a ruler in the photo. DartFit takes the median of many frames and drops outliers. The image never leaves your phone; only the measurements in millimetres are used.

No card at hand? You can scan without one; DartFit then keeps only the proportions of your hand and estimates the size from your height, and tells you the result is less precise.

Step 2: from answers to sizes

Every clue is an estimate with an uncertainty: your hand size, where you hold the dart, how many fingers you use, how the dart flies and how much grip you like. DartFit combines them weighted by how certain each one is. The starting point for steel tip is 22 g; your hand and throw move it from there.

• Length follows your fingers: about 44 mm for two fingers on the barrel, 48 mm for three and 52 mm for four, adjusted for your finger length and where you hold it.
• Thickness follows your hand: around 6.8 mm, a little thicker for broad hands.
• Without a scan, your hand is estimated from your height (hand length is on average about 10.75% of body height).

Step 3: physics, so the ideal dart can exist

Weight, length and thickness are tied together: a barrel is metal with a density. DartFit models a barrel from the density of tungsten alloys (ASTM B777), the bores for the point and the thread, and its profile. Calibrated on 34 straight barrels, it predicts their listed weight to within about 7%. If your wish cannot be made in 90% tungsten, it tries 95%; listings whose stated weight does not fit their size are kept out of recommendations until checked.

Step 4: your ideal barrel and its shape

DartFit searches for the profile (how far the front and back taper) that hits your weight and puts the balance point where your grip wants it, leaning towards the shape your hold and hand suggest: torpedo for a front grip, straight for the middle, tapered for the back, bomb for a compact grip with short fingers.

Step 5: the match score

Each real dart gets a distance to your ideal on every size, measured in standard deviations and weighted by how much you would feel the difference. That becomes three numbers: shape match (weight, length, thickness), style match (barrel type, grip, balance) and the total. The result shows the best total in each price class: budget (up to €50), standard (up to €80) and premium.

What DartFit does not claim

No study turns hand size into the perfect dart weight. DartFit gives you a reasoned starting point and a short list to try, with the reasons. Every rule of thumb in the model is listed with its source on the method page in the app, and it is tuned with what players tell us after they buy.