Cow gestation: when is my cow due?
Type the day the cow or heifer was bred. The cow gestation calculator gives the estimated calving date, the normal calving window, how many days along she is today, and when to watch for heat if she did not settle.
- Estimated calving date
- April 30, 2027
Your cow is due to calve about April 30, 2027, between April 26, 2027 and May 4, 2027.
- Earliest normal calving date
- April 26, 2027
- Latest normal calving date
- May 4, 2027
- Days along
- 90
- Days to the estimated calving date
- 193
- Where she is now
- Day 90 of about 283: 193 days to the estimated calving date.
- Next heat if she did not settle
- August 11, 2026
Answer for the example date Monday, October 19, 2026. It changes to today's date when the page loads.
Estimated calving date: April 30, 2027. Your cow is due to calve about April 30, 2027, between April 26, 2027 and May 4, 2027.
How to calculate
Computes a cow’s calving date from the breeding date (283 days), the normal calving window of 279 to 287 days, how many days along she is, and when to watch for heat if she did not settle.
Example with the default inputs (Breeding date July 21, 2026, Today’s date October 19, 2026) on the example date Monday, October 19, 2026: Your cow is due to calve about April 30, 2027, between April 26, 2027 and May 4, 2027.
Method: Calving date = breeding date + 283 days; normal window = breeding date + 279 to 287 days; next heat = breeding date + 21 days.
- The estimate is the average gestation of about 283 days given by Mississippi State University Extension; the window of 279 to 287 days is from Penn State Extension.
- Days count from the breeding date as day 0. Breed, the calf’s sex and the cow’s age change the length a little.
- A cow that did not settle comes back into heat about one estrous cycle (21 days, typically 18 to 24) after breeding.
Worked examples
Each example is checked against the calculator on every build.
- Breeding date 2026-10-01, Today’s date 2026-12-01 gives Estimated calving date 2027-07-11, Earliest normal calving date 2027-07-07, Latest normal calving date 2027-07-15, Days along 61, Days to the estimated calving date 222, Next heat if she did not settle 2026-10-22, Where she is now Day 61 of about 283: 222 days to the estimated calving date..Source: Mississippi State University Extension, Publication 2616, The Estrous Cycle of Cattle (after approximately 283 days of gestation, parturition occurs; the cycle averages 21 days, with a typical range of 18 to 24 days), https://extension.msstate.edu/publications/the-estrous-cycle-cattle (retrieved 2026-10-18); Penn State Extension, Beef Cattle Reproduction and Genetics (typically, gestation ranges between 279 and 287 days), https://extension.psu.edu/animals-and-livestock/beef-cattle/reproduction-and-genetics (retrieved 2026-10-18); 1 October 2026 + 279, 283 and 287 days
- Breeding date 2027-06-01, Today’s date 2028-03-08 gives Estimated calving date 2028-03-10, Earliest normal calving date 2028-03-06, Latest normal calving date 2028-03-14, Days along 281, Days to the estimated calving date 2, Where she is now Day 281: in the calving window (days 279 to 287)..Source: Mississippi State University Extension, Publication 2616, The Estrous Cycle of Cattle (after approximately 283 days of gestation, parturition occurs; the cycle averages 21 days, with a typical range of 18 to 24 days), https://extension.msstate.edu/publications/the-estrous-cycle-cattle (retrieved 2026-10-18); Penn State Extension, Beef Cattle Reproduction and Genetics (typically, gestation ranges between 279 and 287 days), https://extension.psu.edu/animals-and-livestock/beef-cattle/reproduction-and-genetics (retrieved 2026-10-18)
- Breeding date 2026-03-15, Today’s date 2026-12-31 gives Estimated calving date 2026-12-23, Latest normal calving date 2026-12-27, Days along 291, Days to the estimated calving date -8, Where she is now Day 291: past the latest normal calving date (day 287). Call your vet..Source: Mississippi State University Extension, Publication 2616, The Estrous Cycle of Cattle (after approximately 283 days of gestation, parturition occurs; the cycle averages 21 days, with a typical range of 18 to 24 days), https://extension.msstate.edu/publications/the-estrous-cycle-cattle (retrieved 2026-10-18); Penn State Extension, Beef Cattle Reproduction and Genetics (typically, gestation ranges between 279 and 287 days), https://extension.psu.edu/animals-and-livestock/beef-cattle/reproduction-and-genetics (retrieved 2026-10-18)
How it works
The calculator adds whole days to the breeding date:
| Output | Days after breeding | Source |
|---|---|---|
| Estimated calving date | 283 | Mississippi State University Extension |
| Earliest normal calving date | 279 | Penn State Extension |
| Latest normal calving date | 287 | Penn State Extension |
| Next heat if she did not settle | 21 | Mississippi State University Extension, the cycle |
- Days along = whole days from the breeding date to today’s date. The breeding date is day 0.
- Days to the estimated calving date = 283 − days along. It is negative once the date has passed.
- Where she is now, by days along (d): past the latest normal date when d is more than 287 (“Day d: past the latest normal calving date (day 287). Call your vet.”); in the calving window when d is from 279 to 287 (“Day d: in the calving window (days 279 to 287).”); otherwise “Day d of about 283: (283 − d) days to the estimated calving date.”
Rules. Today’s date may not be before the breeding date: then there is no answer and the page says so. Both dates are from 1 January 1900 to 31 December 2200. Calendar days count leap days (2028 has 29 February).
Output format. Dates show as month, day and year. Days along and days to the calving date are whole numbers.
Worked examples by hand
Bred on 1 October 2026, counted on 1 December 2026. From 1 October to 30 June 2027 is 272 days, so + 279, 283 and 287 days are 7, 11 and 15 July 2027. Next heat: + 21 days = 22 October 2026. From 1 October to 1 December is 30 + 31 = 61 days, so 283 − 61 = 222 days to go.
Bred on 1 June 2027, counted on 8 March 2028. 2028 is a leap year. From 1 June 2027 to 29 February 2028 is 273 days, so + 279, 283 and 287 days are 6, 10 and 14 March 2028. On 8 March she is 281 days along, with 2 days to go, in the calving window.
Bred on 15 March 2026, counted on 31 December 2026. + 283 days = 23 December 2026; the latest normal date, + 287 days, is 27 December. On 31 December she is 291 days along: 8 days past the estimate and past the latest normal date, so the page says to call your vet.
Other questions people ask
How long is a cow pregnant?
About 283 days, a little over 9 months. Mississippi State University Extension gives about 283 days from fertilization to calving, and Penn State Extension says gestation typically ranges from 279 to 287 days.
How is the calving date worked out?
The calculator adds 283 days to the breeding date. The earliest and latest normal dates add 279 and 287 days. A cow bred on 1 October 2026 is due about 11 July 2027.
What if I used a bull and do not know the breeding date?
Type the day the bull went in for the earliest calving date, then the day he came out for the latest. The cow was bred somewhere between the two, during a heat, and heats come about every 21 days.
When will she come back into heat if she is not pregnant?
The estrous cycle of cows and heifers averages 21 days, with a typical range of 18 to 24 days. Watch for heat about 21 days after breeding; the calculator shows that date. No heat then is a first sign that she settled.
Do breed and calf sex change the date?
A little. Penn State Extension notes that gestation length varies with breed, body condition, age and the sex of the calf. Use the window of 279 to 287 days, not only the single estimate.
What if my cow goes past the latest date?
Call your vet. Past day 287 a cow is beyond the normal window, and she should be checked.