Gestation Calculator

Cattle gestation chart

Cows carry a calf an average of 283 days. Find the date she was bred in the chart below and read across for the calving date. It prints on a couple of sheets, and it works for any year.

Or just put the date in

283 days

Put in the date she was bred and you will get the due date, the normal window either side of it, and the dates worth writing on the calendar between now and then. The full chart is further down the page.

Cattle gestation table — 283 days

Bred in January
BredDue
Jan 1Oct 11
Jan 2Oct 12
Jan 3Oct 13
Jan 4Oct 14
Jan 5Oct 15
Jan 6Oct 16
Jan 7Oct 17
Jan 8Oct 18
Jan 9Oct 19
Jan 10Oct 20
Jan 11Oct 21
Jan 12Oct 22
Jan 13Oct 23
Jan 14Oct 24
Jan 15Oct 25
Jan 16Oct 26
Jan 17Oct 27
Jan 18Oct 28
Jan 19Oct 29
Jan 20Oct 30
Jan 21Oct 31
Jan 22Nov 1
Jan 23Nov 2
Jan 24Nov 3
Jan 25Nov 4
Jan 26Nov 5
Jan 27Nov 6
Jan 28Nov 7
Jan 29Nov 8
Jan 30Nov 9
Jan 31Nov 10
Bred in February
BredDue
Feb 1Nov 11
Feb 2Nov 12
Feb 3Nov 13
Feb 4Nov 14
Feb 5Nov 15
Feb 6Nov 16
Feb 7Nov 17
Feb 8Nov 18
Feb 9Nov 19
Feb 10Nov 20
Feb 11Nov 21
Feb 12Nov 22
Feb 13Nov 23
Feb 14Nov 24
Feb 15Nov 25
Feb 16Nov 26
Feb 17Nov 27
Feb 18Nov 28
Feb 19Nov 29
Feb 20Nov 30
Feb 21Dec 1
Feb 22Dec 2
Feb 23Dec 3
Feb 24Dec 4
Feb 25Dec 5
Feb 26Dec 6
Feb 27Dec 7
Feb 28Dec 8
Bred in March
BredDue
Mar 1Dec 9
Mar 2Dec 10
Mar 3Dec 11
Mar 4Dec 12
Mar 5Dec 13
Mar 6Dec 14
Mar 7Dec 15
Mar 8Dec 16
Mar 9Dec 17
Mar 10Dec 18
Mar 11Dec 19
Mar 12Dec 20
Mar 13Dec 21
Mar 14Dec 22
Mar 15Dec 23
Mar 16Dec 24
Mar 17Dec 25
Mar 18Dec 26
Mar 19Dec 27
Mar 20Dec 28
Mar 21Dec 29
Mar 22Dec 30
Mar 23Dec 31
Mar 24Jan 1
Mar 25Jan 2
Mar 26Jan 3
Mar 27Jan 4
Mar 28Jan 5
Mar 29Jan 6
Mar 30Jan 7
Mar 31Jan 8
Bred in April
BredDue
Apr 1Jan 9
Apr 2Jan 10
Apr 3Jan 11
Apr 4Jan 12
Apr 5Jan 13
Apr 6Jan 14
Apr 7Jan 15
Apr 8Jan 16
Apr 9Jan 17
Apr 10Jan 18
Apr 11Jan 19
Apr 12Jan 20
Apr 13Jan 21
Apr 14Jan 22
Apr 15Jan 23
Apr 16Jan 24
Apr 17Jan 25
Apr 18Jan 26
Apr 19Jan 27
Apr 20Jan 28
Apr 21Jan 29
Apr 22Jan 30
Apr 23Jan 31
Apr 24Feb 1
Apr 25Feb 2
Apr 26Feb 3
Apr 27Feb 4
Apr 28Feb 5
Apr 29Feb 6
Apr 30Feb 7
Bred in May
BredDue
May 1Feb 8
May 2Feb 9
May 3Feb 10
May 4Feb 11
May 5Feb 12
May 6Feb 13
May 7Feb 14
May 8Feb 15
May 9Feb 16
May 10Feb 17
May 11Feb 18
May 12Feb 19
May 13Feb 20
May 14Feb 21
May 15Feb 22
May 16Feb 23
May 17Feb 24
May 18Feb 25
May 19Feb 26
May 20Feb 27
May 21Feb 28
May 22Feb 29
May 23Mar 1
May 24Mar 2
May 25Mar 3
May 26Mar 4
May 27Mar 5
May 28Mar 6
May 29Mar 7
May 30Mar 8
May 31Mar 9
Bred in June
BredDue
Jun 1Mar 10
Jun 2Mar 11
Jun 3Mar 12
Jun 4Mar 13
Jun 5Mar 14
Jun 6Mar 15
Jun 7Mar 16
Jun 8Mar 17
Jun 9Mar 18
Jun 10Mar 19
Jun 11Mar 20
Jun 12Mar 21
Jun 13Mar 22
Jun 14Mar 23
Jun 15Mar 24
Jun 16Mar 25
Jun 17Mar 26
Jun 18Mar 27
Jun 19Mar 28
Jun 20Mar 29
Jun 21Mar 30
Jun 22Mar 31
Jun 23Apr 1
Jun 24Apr 2
Jun 25Apr 3
Jun 26Apr 4
Jun 27Apr 5
Jun 28Apr 6
Jun 29Apr 7
Jun 30Apr 8
Bred in July
BredDue
Jul 1Apr 9
Jul 2Apr 10
Jul 3Apr 11
Jul 4Apr 12
Jul 5Apr 13
Jul 6Apr 14
Jul 7Apr 15
Jul 8Apr 16
Jul 9Apr 17
Jul 10Apr 18
Jul 11Apr 19
Jul 12Apr 20
Jul 13Apr 21
Jul 14Apr 22
Jul 15Apr 23
Jul 16Apr 24
Jul 17Apr 25
Jul 18Apr 26
Jul 19Apr 27
Jul 20Apr 28
Jul 21Apr 29
Jul 22Apr 30
Jul 23May 1
Jul 24May 2
Jul 25May 3
Jul 26May 4
Jul 27May 5
Jul 28May 6
Jul 29May 7
Jul 30May 8
Jul 31May 9
Bred in August
BredDue
Aug 1May 10
Aug 2May 11
Aug 3May 12
Aug 4May 13
Aug 5May 14
Aug 6May 15
Aug 7May 16
Aug 8May 17
Aug 9May 18
Aug 10May 19
Aug 11May 20
Aug 12May 21
Aug 13May 22
Aug 14May 23
Aug 15May 24
Aug 16May 25
Aug 17May 26
Aug 18May 27
Aug 19May 28
Aug 20May 29
Aug 21May 30
Aug 22May 31
Aug 23Jun 1
Aug 24Jun 2
Aug 25Jun 3
Aug 26Jun 4
Aug 27Jun 5
Aug 28Jun 6
Aug 29Jun 7
Aug 30Jun 8
Aug 31Jun 9
Bred in September
BredDue
Sep 1Jun 10
Sep 2Jun 11
Sep 3Jun 12
Sep 4Jun 13
Sep 5Jun 14
Sep 6Jun 15
Sep 7Jun 16
Sep 8Jun 17
Sep 9Jun 18
Sep 10Jun 19
Sep 11Jun 20
Sep 12Jun 21
Sep 13Jun 22
Sep 14Jun 23
Sep 15Jun 24
Sep 16Jun 25
Sep 17Jun 26
Sep 18Jun 27
Sep 19Jun 28
Sep 20Jun 29
Sep 21Jun 30
Sep 22Jul 1
Sep 23Jul 2
Sep 24Jul 3
Sep 25Jul 4
Sep 26Jul 5
Sep 27Jul 6
Sep 28Jul 7
Sep 29Jul 8
Sep 30Jul 9
Bred in October
BredDue
Oct 1Jul 10
Oct 2Jul 11
Oct 3Jul 12
Oct 4Jul 13
Oct 5Jul 14
Oct 6Jul 15
Oct 7Jul 16
Oct 8Jul 17
Oct 9Jul 18
Oct 10Jul 19
Oct 11Jul 20
Oct 12Jul 21
Oct 13Jul 22
Oct 14Jul 23
Oct 15Jul 24
Oct 16Jul 25
Oct 17Jul 26
Oct 18Jul 27
Oct 19Jul 28
Oct 20Jul 29
Oct 21Jul 30
Oct 22Jul 31
Oct 23Aug 1
Oct 24Aug 2
Oct 25Aug 3
Oct 26Aug 4
Oct 27Aug 5
Oct 28Aug 6
Oct 29Aug 7
Oct 30Aug 8
Oct 31Aug 9
Bred in November
BredDue
Nov 1Aug 10
Nov 2Aug 11
Nov 3Aug 12
Nov 4Aug 13
Nov 5Aug 14
Nov 6Aug 15
Nov 7Aug 16
Nov 8Aug 17
Nov 9Aug 18
Nov 10Aug 19
Nov 11Aug 20
Nov 12Aug 21
Nov 13Aug 22
Nov 14Aug 23
Nov 15Aug 24
Nov 16Aug 25
Nov 17Aug 26
Nov 18Aug 27
Nov 19Aug 28
Nov 20Aug 29
Nov 21Aug 30
Nov 22Aug 31
Nov 23Sep 1
Nov 24Sep 2
Nov 25Sep 3
Nov 26Sep 4
Nov 27Sep 5
Nov 28Sep 6
Nov 29Sep 7
Nov 30Sep 8
Bred in December
BredDue
Dec 1Sep 9
Dec 2Sep 10
Dec 3Sep 11
Dec 4Sep 12
Dec 5Sep 13
Dec 6Sep 14
Dec 7Sep 15
Dec 8Sep 16
Dec 9Sep 17
Dec 10Sep 18
Dec 11Sep 19
Dec 12Sep 20
Dec 13Sep 21
Dec 14Sep 22
Dec 15Sep 23
Dec 16Sep 24
Dec 17Sep 25
Dec 18Sep 26
Dec 19Sep 27
Dec 20Sep 28
Dec 21Sep 29
Dec 22Sep 30
Dec 23Oct 1
Dec 24Oct 2
Dec 25Oct 3
Dec 26Oct 4
Dec 27Oct 5
Dec 28Oct 6
Dec 29Oct 7
Dec 30Oct 8
Dec 31Oct 9

Built on a 283-day gestation. Dates are month and day only, so this chart works for any year — with one catch: if the pregnancy runs through 29 February, the real due date lands one day later than the chart says. The calculator at the top of the page already accounts for that.

What the chart cannot tell you

A gestation chart gives you one number because a sheet of paper has to pick one. Real calvings spread out either side of it, and most land between 278 and 290 days.

The chart is also older than most people realize. The 283 figure predates every modern dataset, which put beef cattle nearer 279 or 280 — 278.6 across 101,787 Angus AI matings, 280.2 in a Virginia Tech study. Selection for calving ease shortened it and the printed charts never caught up. If you use low-birth-weight AI sires, calves can come as much as three weeks before the charted date.

Two smaller things move it predictably. Bull calves ride about a day and a quarter longer than heifer calves. Twins come roughly four days early, which matters because twin births are the ones most likely to need you there.

So treat the charted date as the middle of a window rather than an appointment. Have the calving pasture ready a week before it, and do not get worried until you are a week past it.

Questions people actually ask

How do I read a cattle gestation chart?

Find the month she was bred, then the day in the left column. The date beside it is when she is due. That is the whole trick — no arithmetic, no counting days on a wall calendar.

The chart runs on month and day only, with no year, so one printed sheet stays good indefinitely.

Why does the chart say one date and the calculator say another?

Almost always a leap year. The chart has no year in it, so it cannot know that 29 February falls inside a particular pregnancy. When it does, the real calving date is one day later than the chart shows. The calculator works on actual dates and gets it right.

Is the chart for beef or dairy cattle?

Both. It is built on 283 days, which sits between the beef and dairy breeds. Holstein averages 279 and Jersey 280, while Brahman runs to 293 — about a fortnight of spread from one end to the other.

If you run one breed, use the calculator above and pick the bull's breed from the list. The whole chart shifts to match. And it is the bull's breed that matters, not the cow's: the calf sets off labour, and the calf is half the bull.

Can I print this chart?

Yes, and it is built for it. Hit print and you get the twelve months laid out clean across a couple of sheets, with the navigation and buttons stripped out. It is meant to end up taped inside a barn door or folded in the glovebox.

Where these numbers come from

Every figure on this page traces to a university extension publication or a veterinary reference. If you think one is wrong, the sources are right here so you can check it yourself.

Worth knowing

  • 283 days is a planning figure, not a measured average. It predates every modern dataset below. Every modern dataset comes in shorter: 280.2 days at Virginia Tech across 10,037 AI records, 278.6 across 101,787 American Angus matings, 279.0 for Holstein. Selection for calving ease has shortened gestation — Angus lost about 4.3 days between 2000 and 2020.
  • If you are breeding to low-birth-weight "curvebender" AI sires, extension guidance is blunt about this: calves can arrive up to three weeks before the calculated date. Start checking a week before the early edge of the window, not at the middle.
  • Breed is the biggest single lever, and it runs about 14 days from Holstein to Brahman. Bos indicus and Bos indicus crosses should never be run on a 283-day default.
  • Gestation length is highly heritable (0.48 to 0.64), which is why the bull matters so much. Where the breed association publishes a gestation-length EPD, that bull's EPD beats any breed average on this page.
  • A shorter pregnancy costs birth weight — calves put on 1 to 1.5 lb a day at the end, so a 276-day calf can be 10 lb lighter than a 283-day one.
  • Twins average about 4.3 days early, and they are the births most likely to need you there.
  • Red Angus has no separate published figure that we could source. Use the Angus number.

Figures last checked August 2026.

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