Frame size calculator

Frame size cannot be read off a number like 54 or 56 — every brand means something different by it. What every manufacturer measures the same way is stack and reach. Here you get the window for them, from your height and your riding style.

Mountain bike? Frame size with seat angle

Already have a bike in mind? Ask the other way round: what height does it fit?

Without an inseam we estimate it from your height. A measured inseam makes the window more accurate: Barefoot, back against the wall, a book pulled firmly up into your crotch — then from the floor to the top of the book.

Arm length: let your arm hang loose and measure from the point of the shoulder (the bony tip at the top outside of the shoulder) to the bone at the wrist. The hand does not count — how long your fingers are does not matter for your riding position. It is easiest with a second person. Each centimetre of arm moves the reach by 6 to 7 mm.

What stack and reach are

Both numbers are measured from the same point: the centre of the bottom bracket to the top of the head tube, where the stem sits. Stack is the vertical distance — it tells you how high the front of the bike is. Reach is the horizontal distance — it tells you how far ahead of you the handlebar is.

How to find the right size

  1. In your manufacturer's geometry chart, find the “Stack” and “Reach” columns. Every brand lists both.
  2. Choose the size whose reach lies in the window above. Reach belongs to your body: to torso and arms.
  3. Then look at the stack. If it is below the window you will sit lower than you wanted; if it is above, more upright. Spacers under the stem and a stem with a rise make up part of the difference.
  4. Two sizes in the running? Then riding style decides: if you want to sit lower, take the lower stack.

Why a window and not a size

A 54 is a different frame at one brand than at the next, and even within one brand it changes from model to model. Stack and reach can be compared. The reach window assumes a shoulder angle as bike fitters measure it on the bike, and a stem from 70 to 120 mm.

Stack, on the other hand, depends on riding style: how low you want to sit decides which front end suits you.

What this page does not calculate

Standover height — whether you can stand over the top tube. Top tube height is not in any geometry chart this application knows, and an estimated number would be worse than none. Check it when you try the bike: standing over the top tube, there must be clearance between the tube and your crotch.

Stack and reach by height

Windows in millimetres for “Road bike” and “Enthusiast / keen”, with the inseam and the arms that go with a height (height times 0.463 and times 0.34). If your arms are longer or shorter, enter them above. The riding style and bike type above change the table.
Body height Stack Reach
155 cm 445–480 315–360
160 cm 470–505 330–380
165 cm 490–525 350–395
170 cm 515–550 360–405
175 cm 535–570 365–415
180 cm 555–590 380–425
185 cm 580–615 390–440
190 cm 600–640 405–450
195 cm 620–660 415–460
200 cm 645–685 425–475

And then?

The bike fit shows how you sit on a particular frame: knee angle, saddle-to-bar drop and back angle, as a 3D model you can adjust.

To the bike fit with all measurements Compare two bikes Setting up your road bike position

This is a guide value from a calculation, not a made-to-measure suit. If you want it exact, have someone look at you on the bike. This page stores nothing — your input lives only in the address.