Bike
Illustration: on Christmas morning a beaming boy sits on his new bike by the tree, both feet flat on the floor, while his parents smile in the background

Bike sizing without the guesswork

Find your size. Then go ride.

Pop in your height and get a starting size for road, mountain, hybrid, e-bikes and kids' bikes in seconds, pulled from published size charts and linked so you can check every number.

Find my bike size Size by height chart

Bike size finder

Height is all you need. Inseam and bike type sharpen the answer.

Units

General starting ranges only, restated from published guides: road from BikeRadar's chart, mountain from a bike shop's general chart, hybrid and e-bike from one brand's chart (Polygon), kids from Trek and BikeRadar. Every brand sizes differently, so check the size chart for the exact model and take a test ride.

Pick your ride

Every kind of bike sizes a little differently

RoadFast, light, drop bars. Sized in cm.MountainTrails and dirt. Sized XS to XXL.Hybrid & cityCommutes and cruising, upright and comfy.E-bikeSame sizing, plus a motor and a weight limit.KidsSized by wheel: 12 to 26 inches.

At a glance

Bike size by height

Starting sizes from three published charts. "Or" means you're on the boundary: let your inseam, reach and a test ride decide.

Full size-by-height chart

HeightRoad[1 · Oct 29, 2026]Mountain[2 · Oct 29, 2026]Hybrid[3 · Oct 29, 2026]
5'0"XXS or XSXSoutside chart
5'4"SSS
5'8"MMM
6'0"L or XLLL
6'4"XXLXL or XXLXL
Illustration: a beaming young girl rides her first pedal bike while her dad runs alongside cheering

Kids' bikes

Sized by wheel, not age

Kids grow at different rates, so go by height and inseam. Trek's published ranges:[5 · Oct 29, 2026]

WheelHeightAge (rough)
12″3'0"–3'3"2–3
16″3'5"–4'0"4–6
20″3'9"–4'6"5–8
24″4'1"–4'11"8–11
26″4'8" and up10–12

Don't size up to "grow into it": a too-big bike can slow learning and hurt confidence.[5 · Oct 29, 2026] Full kids bike size chart

60-second fit check

Measure your inseam like a bike shop

  1. 1Shoes off, back to the wall

    Feet about 20 cm (8 in) apart.[4 · Oct 29, 2026]

  2. 2Book up

    Pull a hardcover book up snugly between your legs, like a saddle.[6 · Oct 29, 2026]

  3. 3Mark and measure

    Mark the top of the book on the wall and measure down to the floor.[6 · Oct 29, 2026]

How to measure inseam

Illustration: a smiling mountain biker rides a dusty forest singletrack

Before you buy

Your test ride checklist

  • Standover: on a road bike, both feet flat with at least 1 cm to spare over the top tube;[1 · Oct 29, 2026] on a mountain bike, at least 2 inches.[2 · Oct 29, 2026]
  • Reach decides between sizes: longer feels more stable at speed, shorter more nimble.[2 · Oct 29, 2026]
  • Same label, different fit: two bikes with the same stated size can put you in very different positions.[1 · Oct 29, 2026]
  • Room to adjust: make sure there's enough adjustment to fine-tune the fit after you buy.[1 · Oct 29, 2026]

Sizing guides

Get the details

Sources: 1. BikeRadar, Road bike sizing. 2. Ridley's Cycle, Mountain bike size chart and fit guide. 3. Polygon Bikes, Sizing guide (height charts by bike type). 4. Gazelle, Bike frame size chart. 5. Trek, Kids bike buyer's guide by age and size. 6. BikeRadar, Bike sizes for kids. Checked Oct 29, 2026. Trademarks belong to their owners; charts are restated in our own tables, not reproduced.