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Cattle Gestation Chart

A cow carries her calf for about 283 days, but breed, calf sex and her own age can move the date by a week or more. Work out a due date, compare 12 breeds, follow the calf month by month and know when calving needs help.

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Figure 1. The Cattle Gestation Chart poster: 283 days month by month, 12 breeds, a due date table, pregnancy checks, calving signs and labor stages. Select it to open full size, then zoom in.

Contents

  1. 1Working out the due date
  2. 2Breed sets the length
  3. 3Due dates for every breeding date
  4. 4The calf month by month
  5. 5Confirming she is bred
  6. 6Heat cycles and breeding back
  7. 7Calving signs, stages and help
  8. 8Heifers, bull calves and twins
  9. 9Feeding the pregnant cow
  10. Sources and notes

1.Working out the due date

Most herds count 283 days from breeding. Pick a breed to use its own average, and adjust for a first-calf heifer, the calf’s sex or twins if you know them. The list then gives every date worth writing on the calendar, from the first pregnancy check to the day she should be bred again.

Calf sex, if known from an ultrasound

Bull calves are carried about 1.2–1.5 days longer than heifer calves, so each shifts the average by under a day.

An Angus cow and a Hereford cow standing together, drawn side by side
Expected calving date Feb 22, 2027 283 days (average). About two in three cows calve between Feb 17 and Feb 27.

Today is day 145 of 283: month 5, 2nd trimester, 138 days to go. The calf is about 35 cm long, about the size of a large cat.

  • Fri May 15, 2026Bredday 0
  • Fri Jun 5, 2026Watch for a return to heatno heat suggests she is pregnant
  • Fri Jun 12, 2026Earliest blood or ultrasound testultrasound from day 26–32
  • Fri Jun 19, 2026Earliest rectal palpationroutine checks at 45–60 days
  • Tue Jul 14, 2026Fetal sex visible on ultrasoundskilled operator
  • Tue Aug 18, 20262nd trimester begins
  • Fri Nov 20, 20263rd trimester beginsenergy needs rise about 21%
  • Mon Feb 8, 2027Udder filling, mucus plug may passwatch more closely
  • Mon Feb 22, 2027Due date
  • Sat Apr 3, 2027Uterus recoveredabout 40 days or more
  • Sat May 15, 2027Bred back byfor a calf every 365 days

2.Breed sets the length

Breed is the biggest single reason one cow calves earlier than another. Dairy breeds such as Holstein and Jersey average about 279–280 days, British beef breeds 282–284, the big Continental breeds 289–291 and Brahman 293, a gap of two weeks. Crossbred calves land between their parents.

Six breeds drawn to one scale: Holstein, Hereford, Angus, Jersey, Charolais and Brahman cows standing side by side
Figure 2. Six of the twelve breeds compared below.
dairyBritish beefContinental beefBrahman and Brahman cross283-day average

Dairy breeds: purebred cows in US national records (Norman and others, 2009); heifers run about 1–1.6 days shorter. Beef breeds: calves sired by bulls of each breed in the USDA-MARC Germplasm Evaluation herds. Brangus: Southern Cooperative Series Bulletin 405.

3.Due dates for every breeding date

Pick the month she was bred to see the expected calving date for every day of it. The table uses 283 days unless you choose a breed, and it skips nothing: a February 29 breeding is listed in leap years only.

Month bred
May breedings, 283 days
BredDueWeekday
May 1Feb 8Mon
May 2Feb 9Tue
May 3Feb 10Wed
May 4Feb 11Thu
May 5Feb 12Fri
May 6Feb 13Sat
May 7Feb 14Sun
May 8Feb 15Mon
May 9Feb 16Tue
May 10Feb 17Wed
May 11Feb 18Thu
May 12Feb 19Fri
May 13Feb 20Sat
May 14Feb 21Sun
May 15Feb 22Mon
May 16Feb 23Tue
 
BredDueWeekday
May 17Feb 24Wed
May 18Feb 25Thu
May 19Feb 26Fri
May 20Feb 27Sat
May 21Feb 28Sun
May 22Mar 1Mon
May 23Mar 2Tue
May 24Mar 3Wed
May 25Mar 4Thu
May 26Mar 5Fri
May 27Mar 6Sat
May 28Mar 7Sun
May 29Mar 8Mon
May 30Mar 9Tue
May 31Mar 10Wed

Calving dates are averages. In large herd records, individual pregnancies spread about 5 days either side of the breed mean.

4.The calf month by month

For the first two months the embryo is smaller than a mouse. By month six it is the size of a beagle, and about 70% of its growth comes in the last 60–90 days, which is why late pregnancy feeding matters so much. Choose a month to read what is happening inside.

2nd trimester · days 91–120 Month 4: about 24 cm 9.5 in · about the size of a small cat · about 2 kg (4 lb)

Hooves are firm and distinct.

Bar heights show fetal length (crown to rump) to scale. Size comparisons follow the University of Florida Drost Project; landmarks are typical, not exact.

  • Month 1days 0–30about 1 cm. Embryo about 9 mm long at day 28; heartbeat visible on ultrasound from day 26.
  • Month 2days 31–605–8 cm, a mouse. Hooves start to form; the calf’s sex can be seen on ultrasound by about day 60.
  • Month 3days 61–90about 14 cm, a rat. The four stomachs are recognizable; placentomes and the uterine artery pulse can be felt from about this month.
  • Month 4days 91–120about 24 cm, a small cat; about 2 kg (4 lb). Hooves are firm and distinct.
  • Month 5days 121–150about 35 cm, a large cat; 2.5–3 kg (5.5–6.6 lb). First tactile hairs appear on the lips, chin and eyelids.
  • Month 6days 151–180about 46 cm, a beagle. Eyelashes grow; the body is still bare except around the lips and eyes.
  • Month 7days 181–210about 60 cm. Hair grows on the tail switch, at the poll and around the hooves.
  • Month 8days 211–24065–85 cm; 15–25 kg (33–55 lb) by day 240. Hair covers the back and the edges of the ears; growth is now fastest.
  • Month 9days 241–28380–100 cm. A full hair coat; the calf turns into the birth position, front feet and nose first.

5.Confirming she is bred

A cow that does not come back into heat about 21 days after breeding is probably pregnant, but only a test confirms it. The earliest dates below are counted from the breeding date in the calculator.

Pregnancy checks
MethodFromNotes
Ultrasound26–32 daysEmbryo and heartbeat visible from about day 26; open cows reliably found at 28–32 days.
Blood or milk test (PAG)28 daysPregnancy proteins rise quickly between days 24 and 28.
Rectal palpation35 daysMembrane slip from about day 30 in heifers; most herds check at 45–60 days.
Fetal sex by ultrasoundabout 60 daysNeeds a skilled operator.
Uterine artery and placentomes3rd monthThe pulse (fremitus) and placentomes help age the pregnancy.

Your check dates

Bred on May 15, 2026 (from the calculator above).

  • Watch for a return to heatJun 5, 2026
  • Blood or milk testJun 12, 2026
  • Ultrasound (most reliable from day 30)Jun 14, 2026
  • Rectal palpation by a vetJun 19, 2026
  • Routine herd check window opensJun 29, 2026
  • Fetal sex by ultrasoundJul 14, 2026
  • Routine herd check window closesJul 14, 2026

6.Heat cycles and breeding back

A calf a year leaves room for only 82 days between calving and conception, since 283 of the 365 go to pregnancy. Brahman-type cows, with a longer pregnancy, have about 73. The uterus alone needs about 40 days to recover, so there is little slack.

Breeding back after calving

Type
  • Uterus recovered (about)Apr 3, 2027
  • First heat, earliest typicalApr 3, 2027
  • First heat, latest typicalApr 23, 2027
  • Bred by, for a calf every 365 daysMay 15, 2027
  • Next calf due, if bred that dayFeb 22, 2028

First heat comes 40–60 days after calving in well-fed cows and can take 100 days or more in thin ones. Aim for body condition score 5 at calving (6 for first-calf heifers).

Next heats

  • Heat 1: expect aboutMay 15, 2026 (May 12 to May 18)
  • Heat 2: expect aboutJun 5, 2026 (Jun 2 to Jun 8)
  • Heat 3: expect aboutJun 26, 2026 (Jun 23 to Jun 29)

Cycles run 17–24 days (heifers 17–21, cows 18–24). Standing heat lasts about 15 hours (6–24), and 70% of mounting happens between 6 pm and 6 am, so watch early morning and late evening.

The heat cycle in figures
21 daysaverage cycle; normal range 17–24 days
15 hoursaverage standing heat, range 6–24 hours; heifers stand longer and more often than cows
24–32 hfrom the start of standing heat to ovulation
Day 17the corpus luteum breaks down if she is not pregnant, and the next heat builds over about 4 days
35 lbweaning weight lost for each 21-day cycle a cow calves later in the season

7.Calving signs, stages and help

Most cows calve without help, but first-calf heifers need assistance far more often: about 10–15% of them, against 3–5% of mature cows. Knowing the normal timing of each stage is what tells you when to step in.

A Hereford cow with her newborn calf at her side
Figure 3. A cow with her newborn calf.

Signs that calving is near

  1. 1
    2–3 months beforeFirst-calf heifers start to develop an udder, sometimes this early.
  2. 2
    About 2 weeks beforeThe udder fills; the cervical mucus plug may be lost, though it can come weeks early.
  3. 3
    About 24 hours beforePelvic ligaments beside the tailhead go slack; easiest to see in thin or moderate cows.
  4. 4
    2–3 days to neverTeats fill and strut, but only reliably in heavy milkers.
  5. 5
    About 12 hours beforeShe may isolate herself, skip feed, raise or switch her tail.

Many signs are unreliable on their own: some cows show almost nothing until labor starts.

The three stages of labor

  1. 1
    The cervix opens2–6 hours, sometimes 30 minutes to 24 hours; longer in heifers. Restless, tail raised, mucus, standing apart from the herd.
  2. 2
    The calf is deliveredAbout 30 minutes in cows and about 1 hour in heifers (Oklahoma State research). Starts when the water bag shows; front feet come first, soles down, with the nose on top.
  3. 3
    The afterbirth passes30 minutes to 8 hours after the calf. Membranes still attached after 12 hours count as retained: call your veterinarian rather than pulling them.

Labor check

She is a
Normal so farStage 2 usually takes about 1 hour in a heifer. Leave her quiet and check every 15–30 minutes.

Call for help when

  • No progress 30 minutes after the water bag or feet appear in a cow, or 1 hour in a heifer
  • The calf is not delivered within 2 hours of the feet showing
  • Only one leg, the tail, the head alone or upside-down feet are showing
  • Hours of stage 1 straining with nothing showing
  • The afterbirth is still hanging after 12 hours
  • She is weak, bleeding heavily or stops trying

These are general rules from extension and veterinary sources. Your own veterinarian’s advice for your herd comes first.

8.Heifers, bull calves and twins

Three things besides breed move the calving date: the dam’s age, the calf’s sex and the number of calves. None is large, but together they explain why a heifer carrying a heifer calf can calve several days before a mature cow carrying a bull.

First-calf heifers and mature cows
First-calf heiferMature cow
Gestationabout 1.5–2 days shorterbreed average
First breeding13–15 months, at 65–70% of mature weightyearly, about 82 days after calving
Body condition at calvingscore 6score 5
Needs help calving10–15%3–5%
Stage 2 laborabout 1 hourabout 30 minutes
Breeding seasonstart at least 3 weeks before the cowsmain season
Two Hereford calves a few days old, a bull calf and a heifer calf, facing each other
Figure 4. Bull and heifer calves look alike at birth; the bull calf was carried a little longer.
  • +1.2 to 1.5 dayslonger for bull calves than heifer calves (Angus and Simmental records)
  • 4.7–5.6 daysshorter for twin pregnancies than single calves
  • about 1 lbextra birth weight for each extra day in the womb, often 2 lb in large breeds

9.Feeding the pregnant cow

A cow’s needs follow her calendar. Early pregnancy overlaps with nursing last year’s calf, the middle third is the easiest, and from the second to the third trimester she needs about 21% more energy and 12% more protein to keep up with the calf.

Minimum daily needs of a 1,300 lb beef cow at body condition score 5
StageDry matter, lb per dayCrude protein, % of dietTDN, % of diet
1st trimester (still nursing)309.5%57%
2nd trimester (dry)227.5%50%
3rd trimester257.5%54%
Early lactation, after calving3310.4%59%

From Hall 2025, adapted from Lalman and Holder 2024. TDN is total digestible nutrients, a measure of energy. Pregnant heifers need richer diets because they are still growing.

Sources and notes

Figures are averages from extension services, breed research and veterinary references. Individual cows vary, and a calving that is not progressing is always a reason to call your veterinarian.

  1. Beef Improvement Federation, BIF wiki: Gestation Length (Angus and Simmental averages, calf sex and dam age effects)
  2. B. Freking, Oklahoma State University Extension: Calving interval and gestation length, with USDA-MARC Germplasm Evaluation breed data
  3. H. D. Norman and others, 2009: Genetic and environmental factors that affect gestation length in dairy cattle. Journal of Dairy Science 92:2259–2269
  4. Southern Cooperative Series Bulletin 405 (S-243, S-277): A compilation of research results involving tropically adapted beef cattle breeds
  5. University of Florida Drost Project: bovine reproduction, pregnancy diagnosis and fetal aging
  6. Merck Veterinary Manual: Pregnancy determination in cattle; Management of calving in cattle
  7. University of New South Wales Embryology: Bovine development (fetal landmarks by month)
  8. C. H. Krog: Age assessment of the bovine fetus (citing Roberts 1986 fetal weights)
  9. Mississippi State University Extension P2616: The estrous cycle of cattle; P2488: Replacement beef heifer development
  10. University of Wisconsin-Madison Extension: Estrus detection and estrus detection aids
  11. Nebraska Extension BeefWatch, Rasby and Meyer 2023: Cow herd report card II
  12. SDSU Extension: Nutritional needs prior to calving
  13. Texas A&M AgriLife Extension E-246: Recognizing and handling calving problems
  14. Beef Quality Assurance, J. Herman 2022: Monitoring calving stages and when to intervene
  15. Oklahoma State University Extension: Calving time management for beef cows and heifers
  16. G. Selk, Oklahoma State University, in Progressive Cattle: Signs of impending calving in cows or heifers
  17. Oregon State University Extension, B. Cappellozza: Strategies for developing replacement heifers
  18. H. Smith Thomas, Hereford World 2014: 283 days, gestation length and birth weight
  19. J. B. Hall 2025, Applied Reproductive Strategies in Beef Cattle: Cow herd nutrition during pregnancy (adapted from Lalman and Holder 2024)