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New to the app? Start with your first match in five minutes and where to put your phone.
Frequently asked questions
Where should I put my iPhone?
Behind one baseline, in the middle, pointing down the court, with the whole court in view: both baselines and both sidelines. The app checks your framing and will tell you to move back or centre the phone if needed. Higher is better. A tripod or a secure spot at head height or above gives a clearer view of the far court and of where the shuttle lands. Keep the phone still for the whole match, and make sure it is safely out of the way of players.
What does “Mark the court” mean?
The app needs to know where the court lines are to call lines, measure speed and place shots on the court. It usually finds the court by itself. If it cannot, it asks you to mark the court: drag the four corners onto the outer court lines, starting with the two corners closest to the camera. If part of the court is cut off, you can drag a corner past the edge of the video. Press and hold for a magnifier. You can adjust the corners later from the match.
Should I film at 60, 120 or 240 fps?
A smash crosses the court in a fraction of a second, so more frames per second means more positions of the shuttle to measure, and a more accurate speed. As a guide, the expected error in a speed reading is around 20% at 30 fps, 12% at 60 fps, 6% at 120 fps and 3% at 240 fps. Higher frame rates also make bigger files and use more battery. 120 fps is a good balance for club play. Choose 240 fps when smash speed matters most.
Why does a line call say “Too close”?
From a single camera, the exact landing spot always has some uncertainty, more so on the far side of the court. When the shuttle lands so close to a line that the app cannot be confident either way, it says “Too close” instead of guessing. You decide the point, the same as you would on court. Filming from higher up, keeping the whole court in view and using a higher frame rate all reduce how often this happens.
The score is wrong. How do I fix it?
Open the match, go to Rallies, and press and hold (or swipe) the rally that went the wrong way, then choose who won it. The whole match re-scores instantly, including servers, sides and later games. If the app missed a rally completely, scrub the video to it and choose “Add a missed rally at the playhead”. Changed your mind? Every fix can be undone and redone from the ••• menu. Points the app was unsure about are collected under “Points to confirm”, so you can check them quickly.
Can it show speeds in mph?
Yes. In the app, go to Settings > Speed and choose km/h or mph. Every speed in the app, on share cards and in the widgets follows your choice.
Can I keep using my iPhone while a match is analysed?
Yes. Analysis keeps going in the background for as long as iOS allows and carries on by itself if it is interrupted. If you allow notifications, the app tells you when the match is ready. These notifications are created on your iPhone; nothing comes from a server.
How does it know whether we played singles or doubles?
It counts the players on court in the video and picks singles or doubles automatically, which also sets the scoring rules. If it got it wrong, for example because someone walked across the court, change it from the match with one tap and the match is re-scored for the right format.
Where are my videos, and how do I free up space?
Everything is stored inside the app on your iPhone. Nothing is uploaded. To see how much space the app uses, go to Settings > Storage in the app. To free space, delete the video of an old match but keep its stats (open the match, choose delete, then “Delete video only”), or remove videos in bulk from Settings > Storage. Stats, scores and replays stay when videos are removed; highlight reels need the original video. Deleting the app removes all of its data.
How do I share a highlight?
Open a match and go to Studio. Choose a highlight reel or a share card, pick a format such as vertical for stories, and tap Share to send it with the share sheet or save it to Photos. You can blur or replace faces before you share.
The Live Activity is not showing on my Lock Screen.
Check that Live Activities are turned on for Badminton Sensei: open the Settings app, go to Badminton Sensei, and turn on Live Activities. Also check Settings > Face ID & Passcode (or Touch ID & Passcode) and allow Live Activities when locked. The scoreboard appears once a match is being filmed. Low Power Mode can delay updates.
Crew sharing cannot find my friend’s iPhone.
Crew sharing works directly between iPhones, without the internet, so both phones need to be nearby with the app open. On both phones, allow Local Network access for Badminton Sensei (Settings > Privacy & Security > Local Network) and keep Wi‑Fi and Bluetooth turned on. You do not need to be connected to the same Wi‑Fi network.
Does it need an internet connection or an account?
No. The app makes no network requests and has no account. It works in gyms with no signal. See the privacy policy for details.
System requirements
| Device | iPhone only |
|---|---|
| Software | iOS 26 or later |
| Price | Free, with no in-app purchases |
| Internet | Not required. All analysis runs on your iPhone. |
| For best results | A tripod or stable mount, the whole court in view, and enough free storage for video, especially at high frame rates. |
A note on accuracy
Speeds, line calls and shot names are estimates from a single phone camera. The app shows when it is unsure, and you can correct anything. Badminton Sensei is for practice and fun, not for official match officiating. See the terms of use and the privacy policy.