Tennis serve: check your form with your phone
The serve is the one stroke you control from start to finish, which makes it the most trainable. A good serve is a rhythm: a consistent toss, a deep knee bend, then an explosive reach that ends with the forearm rotating through the ball.
No equipment needed. Practise at home. Just do the swing properly in front of your phone. No court, ball or shuttle is needed, and a racket is optional: the coach judges your movement, so a shadow swing at home in a hallway or garden is enough.
What good looks like
- Toss the ball up and slightly in front, in line with your hitting shoulder, high enough to reach it at full stretch.
- Reach the trophy position with knees bent, tossing arm up and the racket behind you.
- Drive up with the legs and reach as high as you can, with the elbow leading the racket head.
- Rotate the forearm through the ball (pronation) and finish across the front of your body.
Common mistakes and how to fix them
An inconsistent toss
Everything else follows the toss. Practise it alone until the ball lands in the same spot every time.
Contact too low
A bent arm at contact costs height and power. Reach up and extend.
No leg drive
A serve from the arm alone is slow and tiring. Bend the knees and push up into the shot.
What Formanti checks on your serve
At the top of the reach, not at the follow-through where the arm is already coming down.
- Reach: hand clearly above your shoulder. an overhead shot is hit up high
- Arm height at the top: 135–180°. Arm above ear, body fully stretched
- Elbow: 130–180°. Full extension at contact, ball at peak racket reach
- Elbow lead: elbow up before you swing. lead with the elbow, then throw
- Speed: against your own other swings. power comes from a quick whip, not a push
Your ready stance
Hold still between swings and the coach talks you into position.
- Knees: 115–165°. Soft, bent knees let you push off in any direction
- Back lean: 0–30° forward. A little forward: not upright, not hunched
- Feet apart: 1.2–2.2× shoulder width. Feet wider than your shoulders, for balance
What your report looks like
When you finish, you get a report like this one.
- How many swings were in range, out of how many.
- The one thing to work on next, then the next, each with a drill.
- Every swing as a picture with your skeleton on it: ticked, or flagged with what was off.
What you hear and see when you are off
Hand not high enough
The coach says: “Reach up, hit it at the very top.”
On screen: Reach up: hit it above your head.
Drill: Shadow 10 swings and freeze at the top: your hand should be clearly above your head before you whip down.
Arm too low
The coach says: “Get that arm up a bit higher.”
On screen: Lift your hitting arm a lot higher at the top of the swing.
Drill: Shadow 10 swings in slow motion and freeze at contact: check where your elbow is before you speed up.
Arm too high
The coach says: “Keep that arm a bit lower.”
On screen: Keep your hitting arm lower at the top of the swing.
Drill: Shadow 10 swings in slow motion and freeze at contact: check where your elbow is before you speed up.
Arm too bent
The coach says: “Straighten the arm more. Meet it long.”
On screen: Straighten your arm a lot more through contact.
Drill: Slow shadow swings, pausing at contact: your arm should be almost straight with a soft bend.
Arm locked straight
The coach says: “Keep a little bend in the elbow.”
On screen: Keep more bend in your elbow at contact.
Drill: Slow shadow swings, pausing at contact: keep a soft bend and finish with a wrist snap.
Elbow not leading
The coach says: “Get your elbow up before you swing.”
On screen: Get your elbow up before you swing.
Drill: Without a racket, point your hitting elbow at the sky, hold it a second, then throw your hand up to the top.
A slow swing
The coach says: “Swing through faster. Snap it.”
On screen: Swing through faster.
Drill: Shadow swings with a loose grip and a loud 'whoosh' at the top.
Legs too straight in your stance
The coach says: “Bend your knees”
On screen: Bend your knees.
Drill: Hold a low ready stance for 20 seconds between reps.
Hunched over in your stance
The coach says: “Chest up, don't hunch”
On screen: Chest up, don't hunch.
Drill: Hold the ready stance with your chest proud for 20 seconds.
Drills you can do alone
- Toss only: toss 10 balls without hitting them and let them fall. They should all land in the same spot, about a racket's length in front.
- Slow-motion serve: serve at quarter speed, pausing at the trophy position and at contact, checking elbow and hand height.
How to set up your phone
Prop your phone up 2 to 3 metres away with your whole body in view, at about hip height. For the serve, stand side-on to the camera on your hitting side: how far in front you make contact and how big your backswing is can only be judged from the side. It all runs on your phone and nothing is uploaded.
Frequently asked questions
How can I improve my tennis serve without a court?
Practise the toss and the motion at home. Shadow serves in slow motion, with a pause at the trophy position and at contact.
Why do my serves go into the net?
Usually contact is too low or the toss is too far out in front. Reach higher and toss a little more upward.
More tennis practice
Forehand · Backhand · Volley · Overhead smash · Slice backhand · Lob · Drop shot