Size Guide
The most expensive mistake in powersports is buying one size too big.
Kids grow, we get it, and a machine is a lot of money. The temptation to buy the next size up so they can "grow into it" is completely understandable and it is also the single most common cause of a scared kid who never rides again, or worse.
A machine that is too big cannot be controlled. A machine that is slightly too small is simply fun. Buy for the rider you have today.
The two foot test, and it is not optional
Sit your rider on the machine in normal riding position. Both feet down.
- Balls of both feet flat on the ground: this is the fit you want.
- Tiptoes on both sides: too tall. Skip it.
- One foot down, one foot dangling: way too tall. Absolutely skip it.
At a dead stop on uneven ground, that footing is the only thing keeping the machine upright. No amount of enthusiasm makes up for it.
One thing you should know before you read any age below. Coolster publishes no recommended rider age for any of their machines. We checked all thirteen product pages. So every age on this page is our own recommendation, worked out from the published seat height and the transmission type. We would rather give you our honest read and label it as ours than leave the column blank or borrow a number from somewhere else.
ATV seat heights, smallest to largest
| Model | Seat height | Transmission | Our recommendation |
|---|---|---|---|
| ATV-3050B2 110 Youth ATV | 23.2 inches (590 mm) | Fully automatic, nothing to shift | 6 to 9, first machine |
| ATV-3125R2 125 Youth ATV | 23.6 inches (600 mm) | Fully automatic, nothing to shift | 8 to 12 |
| ATV-3125R 125 Junior ATV | 24.4 inches (620 mm) | Fully automatic, nothing to shift | 10 and up, some experience |
| Lander XD-125UF Utility ATV | 28.0 inches (710 mm) | Fully automatic, nothing to shift | 12 and up, or a small adult |
| ATV-3200S Full Size Sport ATV | 31.9 inches (810 mm) | Fully automatic, nothing to shift | Adults and licensed teens 16+ |
| ATV-3250S Full Size Sport ATV | 33.3 inches (845 mm) | Semi automatic, foot shift, no clutch lever | Experienced adults only |
Dirt bike seat heights, smallest to largest
| Model | Seat height | Transmission | Our recommendation |
|---|---|---|---|
| QG-210 70 Kids Dirt Bike | 23.6 inches (600 mm) | Semi automatic 3 speed, foot shift, no clutch lever | 7 to 11, can ride a bicycle |
| QG-213A 110 Youth Dirt Bike | 23.6 inches (600 mm) | Fully automatic, nothing to shift | 7 to 11, first dirt bike |
| M-125 Full Size Dirt Bike | 28.7 inches (730 mm) | Manual clutch with a foot shifter | Adults and experienced teens |
| XR-125 Dirt Bike | 30.7 inches (780 mm) | Semi automatic or full manual, your choice | 11 and up, moving off automatics |
| QG-214-2 125 Pit Bike | 32.3 inches (820 mm) | Manual clutch with a foot shifter | Experienced teen or adult |
Go-karts skip the foot test entirely
The driver sits in a seat behind a roll cage with a belt on, and their feet never touch the ground. So the question is not seat height, it is whether they can press the pedals all the way down with their back flat against the seat. Both of our karts have an adjustable driver seat.
| Model | Seat height | Transmission | Our recommendation |
|---|---|---|---|
| GK-6125 Two Seat Go-Kart | 12.6 inches (320 mm), seated in a cage | Fully automatic with reverse | Youth with an adult, or family |
| GK-6125A Willys Style Mini Jeep | 23.8 inches (605 mm), seated in a cage | Semi automatic with reverse | Teen or adult driver |
This is why a kart is often the right answer for a rider who is small for their age, or nervous, or who simply is not ready for two wheels yet. Nobody falls off a go-kart.
Measure, do not guess
Stand your rider against a wall in the boots they will actually ride in. Measure the inseam from the floor to the crotch. That number needs to be at or above the seat height in the table, with a little to spare. An average ten year old runs somewhere around a 24 to 26 inch inseam, but averages are useless when it is your kid, so measure yours.
Then open the comparison table to see all thirteen machines side by side, or run the Rider Fit Finder for a straight answer in about two minutes. Or call us and describe your rider. That is genuinely the fastest way, and nobody here works on commission.