What size full length mirror do you need?

Light travels to a flat mirror and bounces back at the same angle it arrived. A ray from the top of your head to your eye reflects at a point exactly halfway between the two, and a ray from your feet to your eye reflects at a point halfway between your eye and the floor. Add those two halves together and the glass needs to span half your total height, from half your eye height up to half the distance from your eye to the top of your head.

The part that surprises people is that distance makes no difference. Step back and the angles change, but the halfway points stay where they were. You cannot see more of yourself in a short mirror by standing further away. Try it with a small hand mirror: whatever you can see of your face at arm's length is what you can see from across the room.

So a 180cm person needs 90cm of glass, a 165cm person needs 83cm, and a child of 120cm needs 60cm. The reason nobody sells 90cm full length mirrors is everything that happens around that bare minimum.

Three things push the practical minimum up from half your height to about 140cm. First, the mirror does not sit on the floor. A wall mirror hangs with its bottom edge 20 to 40cm up; a free standing mirror has a stand that lifts the glass 5 to 15cm. Every centimetre of that gap is a centimetre of reflection lost from your feet unless the mirror is tall enough to compensate. Second, you want to see shoes, and most people want a hand's width of floor around them to judge trouser length. Third, nobody stands dead centre. You lean, you turn, you step to the side, and a margin of 10 to 15cm top and bottom stops your head disappearing when you do.

Put those together and a 175cm person hanging a mirror with its base 30cm off the floor needs roughly 88cm of glass plus 30cm for the gap plus 20cm of margin, which is about 140cm. That is the floor of the full length category and why mirrors below it are sold as dressing or hallway mirrors instead.

Width follows the same halving rule across your body. A person 45cm across the shoulders needs 23cm of glass to see shoulder to shoulder, which is why a 30cm wide over-door mirror technically works. It also feels like looking through a letterbox. Width is about comfort and about what else you want in the picture.

At 40cm you see yourself. At 50 to 60cm you see yourself with room either side, which is where most bedroom mirrors sit and why 160 x 50cm and 160 x 60cm are the bestselling sizes in the country. At 70 to 80cm you can hold an outfit up beside you or see a coat swing. From 90cm two people fit, and from 100cm the mirror starts to work as a room feature that reflects light and space rather than just a person. The large full length mirror page covers the 170 to 200cm tall, 80 to 120cm wide sizes.

For a narrow hallway, go tall and narrow: 160 x 40cm or a long mirror at 150 x 35cm keeps the walkway clear and still shows you head to toe because width does not affect that.

A full length wall mirror can be hung wherever you like, so the usual advice is to put the centre of the glass at about 150cm from the floor, roughly eye level for a standing adult. With a 160cm mirror that places the bottom edge at 70cm, which is too high to see your feet. The fix is either to hang it lower, with the bottom edge at 30 to 40cm, or to buy taller. For a wall mirror whose base is 35cm up, add 35cm to the practical minimum in the table above.

A leaner mirror resting against the wall is easier because the frame sits on the floor and the lean tilts the glass back a few degrees. The tilt helps at the top: a back-tilted mirror points its face slightly upward, so it shows more of your head and more ceiling than the same glass hung flat, which is why a leant 150cm mirror shows a tall person head to toe that a hung 150 would crop. The cost is at the floor: lean it steeply and stand close and the glass stops at your ankles; step back a pace and the shoes come back. A standing mirror on its own feet, from a shop that sells them, behaves the same way with the glass lifted a few centimetres by the stand.

In a bedroom, 160 x 50cm is the default and 170 x 76cm is the upgrade. Measure the wall space beside the wardrobe or behind the door before you decide; a 76cm wide mirror on a 90cm wall strip looks crowded. If the room is small, a taller mirror placed so it reflects the window does more for the space than a wider one.

In a hallway, width is the constraint. A 150 to 160cm tall mirror at 40 to 50cm wide, wall mounted, gives you the last check before the door without stealing walkway. Put the centre at 150cm and the base at 35 to 40cm.

In a dressing room or walk-in wardrobe, go wide. 180 x 80cm or 180 x 90cm lets you see a whole outfit and turn, and two people can use it at once. If the room allows, a 200 x 120cm mirror leaning against the end wall makes the space feel double the size.

For a child's room, a 120 x 40cm mirror is plenty until about age 12, and it should be wall mounted or strapped, never free leaning. The arch mirror shapes suit children's rooms well because the curve removes the top corners.

Measure the height from floor to ceiling, or to the bottom of any shelf, picture rail or coving, and subtract 10cm for breathing room. Measure the width of the clear wall strip. Then decide where the mirror will stand or hang and check the three things that catch people out.

A large mirror has three costs beyond price. It weighs more, so a 180 x 80cm framed mirror at 20 to 25kg needs two people to carry and proper wall fixings rather than a hook. It reflects more, which in a small or cluttered room can double the clutter rather than the light. And it dominates: above 170cm a mirror becomes the first thing anyone notices in a bedroom.

If you are choosing between two sizes and the room is under 3m by 3m, take the smaller one and position it well. If the room is larger, or the mirror is going in a hallway or dressing room where it is meant to be seen, take the bigger one. The large full length mirror range starts at 170cm for exactly that second case.

Thin glass bends under its own weight once it is tall. A 3mm sheet at 120cm stays flat in a frame; the same sheet at 170cm develops a faint curve that stretches or squashes the reflection. That is the wobbly hotel-wardrobe effect. 4mm glass is rigid enough for framed mirrors up to about 180cm, which is why most of our range uses it. Over 180cm, and on frameless designs at any size, 5mm is worth the extra weight and cost.

So the size you choose decides the glass you should accept. Up to 160cm, 4mm in any frame is fine. At 170 to 180cm, 4mm in a steel or solid aluminium frame, or 5mm. Above 180cm, 5mm. Every product page on this site states the glass thickness, and the homepage guide explains backing and safety film in more detail.

Single adult, average bedroom: 160 x 60cm, leant with a strap or wall mounted. Tall adult over 185cm who wants it hung flat: 180 x 80cm or 180 x 90cm. Couple sharing a mirror: 180 x 105cm. Narrow hallway: 160 x 60cm wall mounted. Dressing room: 180 x 90cm leaner with an anti-tip strap. Child's room: 150 x 60cm wall mounted or locked with an L-bracket. Rented flat: 160 x 60cm leant, one small screw for the strap. Statement for a living room: 180 x 105cm or 200 x 120cm arch, leaning with a strap.

If you are still between two sizes, email us the room dimensions and your height and we will tell you which one. The delivery page explains what happens on the day it arrives, and the damage guarantee page covers the rare case where it does not arrive in one piece.