A record number of youngsters will take off Friday in the fifth annual Mill Race Marathon Kids Fun Run.

With registration open until just prior to Friday’s race start, 1,300 children have already signed up to compete in one of five age-level heats starting at 6 p.m. at Mill Race Park in the following order.

This year’s total so far exceeds the 1,276 young runners who participated in the 2015 Kids Fun Run. Here are the heat categories.

Tots (younger than pre-K): about 200 meters or 0.12 miles

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Pre-K and kindergarten (with or without parents): 0.5 kilometers or 0.31 miles

Grades 1 and 2: 1 kilometer or 0.62 miles

Grades 3 and 4: 1.5 kilometers or 0.93 miles

Grades 5 and 6: 2 kilometers or 1.24 miles

There is no entry fee for the Kids Fun Run. Register online today, in person at The Commons from 10 a.m. to 4 p.m. Friday or at Mill Race Park from 4:45 until 5:45 p.m. Friday.

Runners and walkers can sign up for Saturday’s Mill Race Marathon, half-marathon or 5K until race day.

Through today, prices will be $85 for the full marathon, $70 for the half-marathon and $35 for the 5K. On Friday and Saturday, it’s $95 for the full marathon, $80 for the half-marathon and $30 for the 5K.

Register at millracemarathon.com.