Tight lambing needs more pens
Synchronised and AI-bred ewes lamb in a burst over a few days. Plan pens for that burst, not for the season average.
Farm Facilities
Lambing Pen Calculator
Enter the ewes due to lamb, how tight your lambing is and how long each ewe stays penned. The calculator works out how many lambing jugs to set up for the busiest days, the floor space they take and the hurdles needed to build them.
- ✓ Runs entirely in your browser
- ✓ No account needed
- ✓ Metric and imperial units
Your result
Lambing Pen Calculator result
Lambing jugs needed12 jugs
The usual rule of thumb is one jug for every 8 to 10 ewes, and more when lambing is tight. Keep a couple of spare hurdles for a ewe that needs longer.
Copied ✓
Estimates for planning only. Results depend on the figures you enter and on typical published values, and real animals and farms vary. Consult a qualified veterinarian, nutritionist or adviser before making animal health, feeding or financial decisions.
The breakdown
Updates as you type- Ewes per jug
- 8.3
- Ewes lambing on a peak day
- 6
- Total jug floor area
- 18 m²
- Hurdles for one row on a wall
- 25
The basics
What Is a Lambing Pen?
A lambing pen, or lambing jug, is an individual pen that holds one ewe and her newborn lambs for the first 24 to 48 hours after birth. A standard jug measures 1.2 x 1.2 m (4 x 4 ft), and a jug for large breeds or multiples measures 1.5 x 1.5 m (5 x 5 ft).
The Lambing Pen Calculator multiplies ewes due by the share of the flock that lambs on a peak day, then by the days each ewe stays penned. A ram-mated flock of 100 ewes peaks at 6 ewes per day and needs 12 jugs for a 2-day stay, which equals 1 jug per 8 ewes.
What the Lambing Pen Calculator Calculates
The Lambing Pen Calculator returns 4 results:
- Jugs needed: pens for the peak of lambing
- Ewes per jug: ewes due divided by pens
- Peak-day lambings: ewes lambing on the busiest day
- Floor area and hurdles: space and panels to build the pens
When to Use the Lambing Pen Calculator
There are 3 main uses for the Lambing Pen Calculator:
- Set up a lambing shed 2 weeks before the first due date
- Order hurdles, water buckets and bedding
- Plan extra pens for synchronised or artificially inseminated (AI) ewes
Getting started
How to Use the Lambing Pen Calculator
To use the Lambing Pen Calculator, follow 3 steps: count the ewes due, then choose the lambing pattern, then set the length of stay. The result updates as you type.
-
Step 1: Count the ewes due
Use the ewes scanned in lamb for the group that will lamb through this shed.
-
Step 2: Choose the lambing pattern
A normal ram-mated flock peaks at around 6% of ewes lambing in a day. Synchronised flocks peak far higher.
-
Step 3: Set the length of stay
One to two days is usual. Allow three for triplets, weak lambs and first-time mothers.
The maths
Lambing Pen Formula
Pens are sized for the busiest day, not the season average.
Jugs = Ewes × Share lambing on a peak day × Days in the jug
Hurdles are counted for a single row of jugs built against a wall: two per jug, plus one to close the end.
Worked example
- Ewes due to lamb 100
- Peak day 6% of the flock, 6 ewes
- Stay in the jug 2 days
- Jugs needed 100 × 6% × 2 = 12, one for every 8 ewes
Reference
Lambing Jugs per 100 Ewes
How the lambing pattern changes the number of pens, with a two-day stay.
| Lambing pattern | Ewes lambing on a peak day | Jugs per 100 ewes |
|---|---|---|
| Normal ram-mated flock | About 6% | 12 |
| Synchronised or AI flock | About 15% | 30 |
| Long, spread-out lambing | About 3.5% | 7 |
Jug size: about 1.2 x 1.2 m (4 x 4 ft) for small to medium ewes and 1.5 x 1.5 m (5 x 5 ft) for large ewes or multiples, with sides at least 90 cm (3 ft) high.
Glossary
Lambing Pen Terms Explained
6 terms appear in the Lambing Pen Calculator and in the guidance around it.
Lambing jug
- A lambing jug is an individual pen for one ewe and her lambs. Penn State Extension recommends jugs of 4 x 4 ft or 5 x 5 ft with sides at least 3 ft (90 cm) high.
Bonding period
- The bonding period is the first 24 to 48 hours in the jug. The ewe learns her lambs, and the shepherd checks that every lamb takes colostrum.
Hurdles
- Hurdles are light panels of wood or steel that link together to form the sides of a jug.
Mixing pen
- A mixing pen holds a small group of ewes and lambs after the jug, before the group joins the main flock.
Bedding
- Clean straw goes into each jug between ewes. Fresh bedding lowers the infection load on newborn lambs.
Twins and triplets
- Ewes with twins stay about 2 days, and ewes with triplets stay about 3 days. Iodine on each navel at birth protects the lambs while they are penned.
Good to know
Setting Up Lambing Pens
3 factors decide lambing pen numbers: the tightness of lambing, pen turnover and space in the mixing pens.
Turnover is the real limit
A jug that takes an hour to muck out and re-bed is out of use for that hour. Clean bedding to hand and a simple routine keep pens moving.
Have somewhere to go next
Ewes and lambs move from jugs into small mixing groups before joining the main flock. Without that space, jugs stay full and the system backs up.
Answers
Frequently Asked Questions
Common questions about the lambing pen calculator and the numbers behind it.
How many lambing pens do I need?
Plan about one jug for every 8 to 10 ewes in a normal ram-mated flock, and more if lambing is synchronised. For 100 ewes that is 10 to 12 jugs.
How big should a lambing jug be?
About 1.2 x 1.2 m (4 x 4 ft) for small to medium ewes and 1.5 x 1.5 m (5 x 5 ft) for large ewes or ewes with multiples. Sides should be at least 90 cm (3 ft) high.
How long should a ewe stay in a lambing pen?
Most ewes and lambs stay 24 to 48 hours. Triplets, weak lambs and first-time mothers often need three days or more.
Do I need lambing pens for outdoor lambing?
Yes, an outdoor lambing flock needs lambing pens, but fewer than a housed flock. A handful of sheltered pens lets you bring in ewes with mismothered, weak or fostered lambs.
🐑 Free · no sign-up · works offline
Get your ewe's exact lambing date in seconds
Enter one breeding date and get the due date, the 142-152 day window and a dated milestone plan, scanning, feeding, vaccination, shearing and lambing.