Ram age and experience
Ram lambs are still growing, tire sooner and serve less efficiently. Start them on small groups and keep them away from dominant older rams.
Breeding & Reproduction
Ram to Ewe Ratio Calculator
Enter how many ewes you are joining, the age of your rams and how the ewes will be mated. The calculator works out how many rams to turn out, using the ranges published by extension services: about 35 to 50 ewes for a mature ram in a normal autumn joining, and fewer for ram lambs, synchronised ewes or rough ground.
- ✓ Runs entirely in your browser
- ✓ No account needed
- ✓ Free to use
Your result
Ram to Ewe Ratio Calculator result
Rams to turn out4 rams
Based on one ram to about 43 ewes, the middle of the 35 to 50 guideline for this ram age and joining type.
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- Working rams
- 3
- Spare rams
- 1
- Ewes per working ram
- 33.3
- Guideline
- 35 to 50 ewes per ram
- Working rams as % of ewes
- 3%
- Fewest to most rams
- 2 to 3
The basics
What Is a Ram to Ewe Ratio?
A ram to ewe ratio is the number of ewes that one ram breeds during a joining period, written as 1:40 for one ram to 40 ewes. Australian and New Zealand guidance states the same figure as a ram percentage, where 2.5% equals 1:40.
The Ram to Ewe Ratio Calculator divides the ewes in a joining group by the ewes one ram covers, then rounds up to give the rams needed. A mature ram covers 35 to 50 ewes in a natural autumn joining, a yearling (shearling) ram covers 26 to 38 ewes and a ram lamb covers 18 to 25 ewes. Synchronised ewes on sponges or CIDRs lower the figure to 10 to 15 ewes per mature ram.
What the Ram to Ewe Ratio Calculator Calculates
The Ram to Ewe Ratio Calculator returns 4 results:
- Rams to turn out: working rams plus the spare ram
- Ewes per working ram: the actual load on each ram
- Guideline range: the published ewes per ram for the ram age and joining type
- Ram percentage: working rams as a share of ewes
When to Use the Ram to Ewe Ratio Calculator
There are 3 main uses for the Ram to Ewe Ratio Calculator:
- Plan ram purchases 8 weeks before joining, in time for a breeding soundness exam
- Split a flock into single-sire or multi-sire joining groups
- Adjust ram numbers for synchronised, teased or out-of-season breeding
Getting started
How to Use the Ram to Ewe Ratio Calculator
To use the Ram to Ewe Ratio Calculator, follow 3 steps: count the ewes in the group, then pick the ram age and joining type, then decide on a spare. The result updates as you type.
-
Step 1: Count the ewes in the group
Enter the ewes going to the ram in one joining group. If you run separate groups, work each one out on its own. A ram cannot be shared across a fence.
-
Step 2: Pick the ram age and joining type
A ram lamb covers about half what a mature ram does. Synchronised, teased and out-of-season ewes all need more ram power.
-
Step 3: Decide on a spare
One extra ram is cheap insurance against lameness, injury or a ram that turns out to be infertile halfway through joining.
The maths
Ram to Ewe Ratio Formula
Divide the ewes by the number one ram can cover, round up, then add a spare.
Rams = Ewes ÷ Ewes per ram, rounded up, + spare
The calculator uses the middle of each published range. Fit, proven rams on good ground can work nearer the top of the range, and young or untested rams nearer the bottom.
Worked example
- Ewes to join 100
- Ewes per mature ram 43 (middle of 35 to 50)
- Working rams 100 ÷ 43 = 2.3, rounded up to 3
- With one spare 4 rams
Reference
Ram to Ewe Ratio Guidelines
Ewes per ram for each joining type and ram age. These are the same figures the calculator uses.
| Joining type | Mature ram | Yearling ram | Ram lamb |
|---|---|---|---|
| Natural joining in season | 35 to 50 | 26 to 38 | 18 to 25 |
| After teasers or the ram effect | 25 to 35 | 19 to 26 | 13 to 18 |
| Hill, rough or very large paddocks | 25 to 40 | 19 to 30 | 13 to 20 |
| Synchronised ewes (sponges or CIDRs) | 10 to 15 | 8 to 11 | 5 to 8 |
| Out-of-season breeding | 5 to 7 | 4 to 5 | 3 to 4 |
Ohio State University Extension lists 35 to 50 ewes per mature ram, and the Merck Veterinary Manual lists about 40. Large extensive flocks in New Zealand and Australia run far more ewes per ram.
Glossary
Ram to Ewe Ratio Terms Explained
6 terms appear in the Ram to Ewe Ratio Calculator and in the guidance around it.
Joining (tupping)
- Joining, called tupping in the UK and Ireland, is the period when rams run with the ewes. Most flocks join for 2 oestrous cycles, about 34 days, in the autumn breeding season.
Oestrous cycle
- The oestrous cycle of a ewe lasts about 17 days, and the ewe stands for the ram for 24 to 36 hours of each cycle.
Ram percentage
- Ram percentage is rams as a share of ewes. Meat & Livestock Australia (MLA) advises 2% plus one ram for maiden ewes, and Beef + Lamb New Zealand reports extensive mixed-age ewes joined at about 1 ram to 150 ewes.
Marking harness (raddle)
- A marking harness holds a crayon on the brisket of the ram and marks each ewe served. A crayon colour change every 17 days shows which ewes return to heat.
Breeding soundness exam
- A breeding soundness exam checks the testicles, feet, teeth and body condition of a ram about 8 weeks before joining.
Ewe lamb
- A ewe lamb is a female in her first year. Ewe lambs have short, weak heats and do not seek out rams, so many flocks join ewe lambs to mature rams in a separate group.
Good to know
What Changes the Ram to Ewe Ratio
3 factors change the ram to ewe ratio: ram age, bunched heats and terrain. A ram serves the ewes that are in heat on the day, not a fixed number of ewes per season.
Bunched heats
Synchronisation and the ram effect put many ewes in heat within a day or two. That short burst, not the season total, is what sets the ram numbers.
Terrain and paddock size
On hill ground or in very large paddocks a ram spends more time walking and less time serving. Drop the number of ewes per ram to make up for it.
Answers
Frequently Asked Questions
Common questions about the ram to ewe ratio calculator and the numbers behind it.
How many ewes can one ram cover?
A mature, fit ram commonly covers 35 to 50 ewes in a normal autumn joining. A ram lamb in his first season is usually given 15 to 25 ewes.
How many rams do I need for 50 ewes?
Two mature rams. At about 43 ewes per ram the sum comes to two working rams for 50 ewes, and running two means a single lame or infertile ram does not leave the flock empty. A third as a spare is optional in a flock this size.
Can a ram lamb breed ewes in his first year?
Yes. A well-grown ram lamb can work from about seven months old, but give him a small group of 15 to 25 ewes and do not rely on him for synchronised or out-of-season joining.
Why do synchronised ewes need more rams?
Sponges and CIDRs bring most of the group into heat over one or two days. One ram can only serve so many ewes in that time, so the ratio drops to about one ram for every 10 to 15 ewes.
🐑 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.