Space for Märklin K Track: what baseboard do you need?

Benjamin | TrackDrawer.com · published 11 November 2026

For a closed loop in Märklin K Track you need a 75 x 75 cm baseboard, with an oval on the tight Industriekreis of 295.4 mm. A loop with a passing loop fits from 140 x 75 cm, and from 120 x 100 cm the Auto-designer lays double track all the way round on Normalkreis I and II. That makes K Track the most compact H0 system in our measurements, provided your rolling stock can handle the tight curve.

We measured this with the TrackDrawer Auto-designer, using an ordinary collection of K Track and a 5 cm clear margin around the baseboard.

Five radii, each 64.6 mm further out

Märklin K Track is H0 three-rail track for AC, without a fixed roadbed: the track sits on its sleepers, 32 mm wide in our catalogue. The five radii are the Industriekreis (295.4 mm), Normalkreis I (360 mm), Normalkreis II (424.6 mm), Großkreis I (553.9 mm) and Großkreis II (618.5 mm). From the Industriekreis to Normalkreis I, from Normalkreis I to II and from Großkreis I to II the step is 64.6 mm each time, which is the track spacing of K Track. Between Normalkreis II and Großkreis I it is exactly twice that.

How K Track differs from C Track in roadbed, turnouts and radii is covered in Märklin C Track or K Track. This article is only about space.

Outside size per radius

The outside size of a circle is twice the radius plus the width of the track. For the baseboard we add a 2 x 50 mm margin.

Each 64.6 mm step costs 12.9 cm of depth. Double track on Normalkreis II and I therefore fits on a baseboard one metre deep (from 120 cm wide in our measurement); on Großkreis II and I you need almost 1.4 m.

The smallest loop: 75 x 75 cm

With 72.3 cm as the lower limit, that becomes a 75 x 75 cm baseboard in 5 cm steps. The designer lays a loop on the Industriekreis there: eight 45 degree curves 2210 with short straights in between, 12 pieces and 1.95 m of track, or an oval of 10 pieces and 1.90 m. In our catalogue the Industriekreis only exists as a 45 degree piece.

On Normalkreis I, the same radius as R1 in C Track, you need 90 cm of depth. On 100 x 90 cm the designer laid a rhombus on Normalkreis I with 18 pieces and 2.58 m of track, or an oval on Normalkreis I with 16 pieces and 2.53 m.

A passing loop: from 140 x 75 cm

The standard K Track turnout (2262 left, 2263 right) is 168.9 mm long and diverges at 22.5 degrees on the Normalkreis II radius. The compensating curve 2232 is a 22.5 degree Normalkreis II curve, and the 156 mm compensating straight 2207 makes up the straight side. Turnout and curve together advance 325 mm; on the straight side it is 168.9 + 156 = 324.9 mm. That is the shortest turnout end of all H0 systems in our catalogue.

That is why a passing loop fits early. At 75 cm deep the designer found the first plan from 140 cm wide: "Station with two platforms on the Industriekreis, plus 2 sidings", 28 pieces and 4.64 m of track. At 85 cm deep, 140 cm remained the smallest width. How a passing loop is built is explained in passing loop: how two trains pass each other.

What fits on common sizes?

Three things stand out:

• On 180 x 90 cm a station on Normalkreis I already fits. So you do not need the Industriekreis there. How K Track compares with the other H0 systems at that size is covered in an H0 layout on 180 x 90 cm.
• On 200 x 120 cm double track wins. Two loops on Normalkreis II and I give 8.86 m of track; a station with two platforms on a single loop comes to 6.93 m.
• On 240 x 120 cm the designer links the two loops with a crossover and adds two sidings. The comparison with other systems at that size is in an H0 layout on 240 x 120 cm.

The Industriekreis: space with a condition

The Industriekreis makes K Track compact, but 295.4 mm is a tight curve. It is meant for industrial sidings and short vehicles. Long coaches overhang the track a lot in it, and not every locomotive gets through. Which radius your rolling stock can handle is stated by its manufacturer. If you want to avoid the Industriekreis, set a minimum radius of 360 mm in the Auto-designer: a loop then needs 90 cm of depth, and a station with two platforms fits on 180 x 90 cm.

Flexible track and short pieces

K Track is the only Märklin H0 system in our catalogue with flexible track: the 2205 at 900 mm. With it you can lay curves with a radius between two fixed radii, or a wider curve if your baseboard allows it. There are also short straights down to 22.5 mm (2204), handy for closing a loop exactly. Flexible track works best combined with fixed pieces around the turnouts.

Frequently asked questions

From what baseboard size does double track fit?

Double track on Normalkreis II and I is 881.2 mm wide on the outside, 98.1 cm with the margin. The designer laid the first double track on 120 x 100 cm: 32 pieces and 5.79 m of track. At 90 cm deep and on 100 x 100 cm it found none; there the passing loop takes priority.

Why does K Track need less space than C Track?

Because of the tighter Industriekreis, the smaller track spacing (64.6 versus 77.5 mm) and the shorter turnout end (325 versus 360 mm). Together that saves 20 cm of width and 15 cm of depth for a loop with a passing loop.

Your own baseboard

Enter your baseboard and your K Track and let the Auto-designer lay a plan that fits.