Whelping Box Setup: Size, Temperature, 2 Bedding Types

Size the box to the queen, not to the room: interior length about 1.5 times her nose-to-tail-base length, which lands at 90 by 60 cm for a 4 to 5 kg queen and 100 by 70 cm for a larger one. Get the temperature wrong and the litter chills in 20 minutes; get the bedding wrong and you change it 6 times a day instead of 2. Those 3 numbers, plus a rail, are the whole job.

This is a preparation page, not a delivery guide. It covers dimensions, 2 heights that matter, a 4-stage temperature curve, and 2 bedding types with wash intervals, all of which can be set up by day 58. Any complication during birth itself is a veterinary matter, and breeding plans in general need professional assessment.

Dimensions: measure the queen, then add 2 numbers

Measure from the base of the tail to the tip of the nose while she stands, then add 50 percent for length and 1 adult body width for height. A typical 4 kg queen measures 60 cm, so the interior becomes 90 by 60 cm. A 6 kg queen measuring 70 cm needs 105 by 70 cm. Depth of 50 cm keeps kittens in from week 3; 30 cm is enough for a small queen but kittens climb out by day 21.

Build or buy 1 box and keep it for the whole season. A cardboard box works for 1 litter but softens within 10 days of washing, and a box replaced mid-litter smells wrong to the queen for 2 to 3 days.

Parameter	Target	Why this number
Interior length	1.5 x queen length, 90 cm for 4 kg	Room to stretch and turn without lying on a kitten
Interior width	60 cm, or 2 adult widths	One adult plus a 6-kitten pile at day 10
Wall height	50 cm, 30 cm for small queens	Kittens stay in until day 21 to 25
Pig rail	10 cm wide, 10 to 12 cm above the floor	Gives kittens an escape gap from a lying queen
Door sill	10 cm, lowered to 5 cm at week 3	Adult steps over; kittens can leave at day 28

The rail and the sill: 2 heights that prevent losses

The rail is the single most skipped part. A 10 cm wide ledge running the inside perimeter at 10 to 12 cm above the floor gives a kitten somewhere to be that is not under the queen's flank. Without it, a 4-day-old kitten in a 90 cm box has 1 option and it is the wrong one.

The sill starts at 10 cm so the queen can step in with a kitten in her mouth and the litter cannot wander at day 14. Lower it to 5 cm around day 28, when kittens need to reach a nearby tray; a sill that stays at 10 cm at week 4 is why litters soil the box instead of the tray 60 cm away.

Temperature: 4 stages, not 1 setting

Newborns cannot regulate heat for the first 10 to 14 days, so the nest surface does the work. Set 29 to 32 C at the surface for days 0 to 7, 27 to 29 C for days 8 to 14, 24 to 27 C for days 15 to 21, and 22 to 24 C from day 22. Ambient room temperature stays 24 to 26 C throughout, with humidity at 40 to 60 percent.

Measure the surface, not the air: a 10 RMB thermometer laid on the bedding under a lamp reads 4 to 6 C higher than the wall thermostat, and that gap is the difference between warm and overheated. Provide a cooler corner at every stage, because a kitten at 32 C with no escape from the lamp dehydrates in 6 hours. A litter that is spread out and panting is too hot; one piled in a single tight heap and cool to the wrist is too cold.

Two bedding types, and how often each is washed

Type 1 is reusable fleece or quilted cotton: 2 to 3 sets cut to the box interior, washed at 60 C with a fragrance-free detergent, dried fully, and rotated daily in week 1. It wicks moisture away from the surface and stays warm when damp, which is why it is the outer layer. Budget 3 sets so 1 is always dry; a set that goes back damp at 40 percent humidity grows odor in 12 hours.

Type 2 is disposable absorbent pads, 60 by 60 cm, laid under the fleece as a backup and used alone for the first 48 hours when fluid is heaviest. Change 2 to 3 times a day in week 1, once a day after week 2. Pads alone are slippery for a newborn trying to crawl 10 cm to a nipple, so they belong underneath, not on top.

Never use clumping litter, towels with loops, or loose blankets in the box. A looped thread wraps a kitten's toe in under 24 hours, and clumping litter in a 30 cm box is a respiratory and ingestion risk in the first 3 weeks.

Placement, light, and noise

Put the box in a corner with 2 walls behind it, at least 1 m from a radiator and out of the path between the door and the food bowl. Ambient noise under 50 dB matters more than most people expect: a washing machine at 70 dB next to the box keeps a queen from settling for 20 to 30 minutes at a time. Keep a dim light on for 12 hours rather than 24, because constant light disrupts the queen's rest in the first week.

Cover 3 sides with a 60 cm panel and leave the front open. A fully covered box at 26 C traps humidity above 70 percent within 4 hours, and a fully open one drops the nest surface by 3 to 4 C in a draught.

What changes in week 1, 2, and 3

Week 1: surface 29 to 32 C, bedding changed daily, box checked at 06:00 and 22:00. Week 2: surface 27 to 29 C, pads every 12 hours, first nail check at day 14. Week 3: surface 24 to 27 C, sill lowered to 5 cm at day 28, and a shallow tray 60 cm from the box. Watching for the shift matters more than the schedule: a queen who starts lying outside the box at day 18 is telling you the surface is 2 to 3 C too warm.

Five steps to finish the setup

Measure the queen standing and write the interior size down before buying anything.
Install the 10 cm rail at 10 to 12 cm above the floor and check it holds 5 kg without flexing.
Set the thermometer on the bedding, not on the wall, and confirm 29 to 32 C at the surface.
Wash 3 fleece sets at 60 C and keep 1 dry set sealed until it is needed.
Have the box, the pads, the 1 g scale, and the clinic number in place by day 58.

Everything that goes beside the box is on the whelping supplies list, and the breed quiz is a 5-minute check on the order.

Frequently asked

How big should a whelping box be for one queen?

Interior length of about 1.5 times her nose-to-tail-base length, which is 90 by 60 cm for a 4 to 5 kg queen and 100 by 70 cm for a larger one. Walls of 50 cm keep kittens inside until day 21 to 25, and a 10 cm sill lets the queen step in.

What temperature should the nest be?

Measure the surface, not the air: 29 to 32 C for days 0 to 7, 27 to 29 C for days 8 to 14, 24 to 27 C for days 15 to 21, and 22 to 24 C after day 22, with room air at 24 to 26 C and a cooler corner always available.

Fleece or disposable pads?

Both, in layers. Fleece or quilted cotton goes on top because it wicks moisture and stays warm, with 3 sets rotated and washed at 60 C. Disposable 60 by 60 cm pads sit underneath as backup and are changed 2 to 3 times a day in week 1.