The slip moves your head just off the punch line: where to evade, which mistakes cost you hits, and why evasion belongs together with counter-punching.
In the slip you shift your head just off the line of a straight punch through a small weight transfer, without taking your hands out of guard. The Swiss coaches' material describes it as "ducking diagonally forward / lateral avoidance": the body bends diagonally forward out of the punch line, weight moves onto the leg of the bending side, the head stays behind the fists [1]. The world federation's manual calls the same movement "ducking to the lead/rear side" [2] – the name "slip" comes from gym language.
How hard is it really? The movement is small, the timing is not. Realistically you need several weeks of regular partner training until you hit the slip at fight tempo (rule of thumb).
And can you react at all? A maximal punch reaches an average of 9.26 m/s at contact, roughly 33 km/h, a briskly ridden racing bike [3]. In combinations contact speed drops to around 8 m/s, and jab and cross take measurably less time to land than a hook. The researchers conclude that a defender may have more time to evade than previously assumed [3]. Evasion is not a miracle but a technique you can practise.
Boxing stance, knees slightly bent. Shift the weight onto one leg and bend the upper body diagonally forward-outward until your head is about one head-width off the centreline. The head stays behind the fists [1] ("one head-width" is a rule of thumb). Milestone: you can do ten slips per side without the guard dropping or looking away from the mirror.
The Swiss material sets the direction: you evade to the outside of the opponent's arm – against a left straight forward-right-sideways, against a right straight forward-left-sideways [1]. Keep your eyes always on the opponent [2]. Milestone: you name the correct side before every punch, before you move.
Your partner guides straights slowly past your head (not onto it!). You evade without touching the punch. The aim is rhythm, not speed. Milestone: ten straights per side, all miss you, your guard stays up.
The Swiss material wants you to couple ducking with a counter-punch as soon as possible: after evading forward-right comes the left straight to the body, and vice versa [1]. Passive defence is not the goal. Milestone: slip and straight run as one movement, then you stand in stance again.
There is also the slip to the inside of the arm. It brings you closer to the opponent's other hand and is therefore more demanding. The sources read contain no instruction on it; it belongs in supervised training after the outside slip sits (practice).
Evading sounds safe because you are not hit. Do it wrong, though, and you are hit, often unprotected. Boxing is a sport with head blows. A meta-analysis of 35 studies found a markedly higher concussion risk in boxing than in other combat sports [4]. In amateur sparring, peak head accelerations reached 191 g, but most impacts were below the threshold for mild head injury [5].
So: no reason for panic, but none for downplaying either. Practise slips first without contact, with a slow partner and controlled tempo. Sparring only under a coach's supervision, with a suitable partner, headgear and 16 oz gloves [2]. Nausea, vomiting, confusion or dizziness after a hit are warning signs: stop immediately and get medical help [2].
This guide explains and motivates; it does not replace supervised training.
Stretch a string at head height across the practice room (for example between two chairs) and slip without touching it. That teaches you to move the head only as far as necessary and is the simplest solo drill for distance feel. Brush the string and you evaded too little; stand metres away and you evaded too much. The string is a practice tip without study evidence.
In a block you catch the punch with glove, elbow or shoulder, in a slip you let it fly past. The slip needs more timing but keeps both hands free to counter. Both belong to basic training [2], and the Swiss material couples defence with a counter-punch as early as possible [1].
To the outside of the opponent's arm: against a left straight forward-right-sideways, against a right straight forward-left-sideways [1]. The weight moves onto the leg of the bending side, the knees stay slightly bent, the head stays behind the fists.
Only a few centimetres, about one head-width. The federation warns of movements that are too wide, too low or too far [2]. The smaller the movement, the faster you are back in stance and the sooner you can counter. The measure is a rule of thumb, not a study value.
A maximal punch lands at about 9.26 m/s; in combinations it is around 8 m/s [3]. Research suggests defenders may have more time than assumed [3]. In practice you first learn expected punches in partner drills, later you read the opponent's shoulder and hip movement.
With mirror and string: ten slips per side, eyes on an imaginary opponent, guard up, then back to stance. Alone you train movement and distance feel, not timing; for timing you need a partner. Start standing: the federation teaches defence first without an opponent, then with a partner [2].
The 1-2 in Boxing: Throwing Jab and Cross as a Combination