Agriculture Calculators

The three breeding calculators in this category — for dogs, goats, and horses — all work the same way: add an average gestation length to the breeding date, then apply a realistic range around it. What differs enormously between them is how wide that range needs to be.

A dog's pregnancy runs 57 to 65 days regardless of breed, and a goat's runs about 145 to 155 days; both are fairly tight windows once you know the average. A horse is a different story. Agricultural extension guidance puts the average mare gestation at 335 to 340 days but treats anything from 320 to 370 days as normal — a 50-day spread, roughly six times wider than a dog's.

That gap isn't random. Research on Warmblood mares found colt foals gestate a few days longer than fillies on average, mares bred earlier in the year (so foals arrive in late winter under shorter daylight) carry longer than mares bred in summer, and a mare's own reproductive history is the single strongest predictor of her own gestation length across pregnancies — stronger than any external factor measured. None of that variation shows up in a dog or goat pregnancy in anywhere near the same degree, which is exactly why the horse gestation calculator's earliest-latest window is so much wider than the dog or goat calculator's.

Whatever species you're working with, treat the calculated due date as the center of a planning window, not a fixed appointment, and lean on physical signs — udder changes, behavior, ligament relaxation — as delivery actually approaches.

The corn yield calculator on this site uses the ear-count method (also called the yield component method), a pre-harvest field estimate originally described by the University of Illinois and still taught by extension programs at Iowa State and Purdue. Rather than waiting for harvest, a grower measures a row length equal to 1/1000 of an acre, counts every harvestable ear in it, then samples a handful of those ears for kernel rows and kernels per row.

Multiplying ears by kernel rows by kernels-per-row gives an estimated kernel count, which gets divided by a "divisor" — the assumed number of kernels, in thousands, needed to fill a standard 56-pound bushel. That divisor is itself an assumption, which is why extension guidance recommends running the same field counts through a low, middle, and high divisor value rather than trusting one number.

The result is directional, not exact — useful for comparing fields, tracking a season against a prior year, or getting an early read weeks before harvest, but not a substitute for what the combine's yield monitor and the elevator scale eventually measure directly.

The grass seed calculator on this site scales a published seeding rate to your actual area, but the rate itself is the number that actually matters, and it varies a lot by species. Tall fescue needs 6 to 8 lb per 1,000 sq ft on bare soil; Kentucky bluegrass needs only 2 to 3 lb because its seed is tiny and the grass spreads on its own through rhizomes; bermudagrass needs just 1 to 3 lb. Overseeding an already-established stand generally runs about half whatever the new-lawn rate is for that species, since existing grass is already covering part of the ground.

Getting the pounds-needed number right only pays off if the seed actually germinates, and timing does more work there than the rate itself. Cool-season grasses establish best seeded in late summer through early fall, when warm soil and cooling air speed germination and give roots a full season before summer heat returns; warm-season bermudagrass needs the opposite calendar, seeded in late spring once soil temperature reaches about 65°F. Soil prep — clearing weeds, loosening the top few inches, and getting good seed-to-soil contact — determines how much of the seed you calculate actually becomes a stand instead of bird food.

This category currently runs dedicated due-date calculators for dogs, goats, and horses, but three other species show real, consistent search demand for the same kind of math: cattle, sheep, and pigs. Anyone tracking a breeding date for those animals can still work out a reliable window using the same averages extension programs publish for dogs, goats, and horses.

Cattle run the longest of the three at roughly 279 to 287 days from breeding, averaging close to 283 — a beef cow and a dairy cow land in slightly different spots within that range, but both track tighter than a horse's 320-to-370-day spread. Sheep average about 147 days, with a normal range of 144 to 151, putting them almost exactly between a goat and a dog in both length and predictability. Pigs are the shortest and the most consistent of any farm animal by a wide margin — the old stockman's rule of "three months, three weeks, three days" lands almost exactly on the real average of 114 days, with most sows farrowing within a 112-to-115-day window.

The same principle that applies to the dog, goat, and horse calculators on this site applies here too: add the average to the breeding date to get a target, then treat the few days on either side as the real window rather than a single fixed date, since even the tightest of these ranges (pigs) still varies by breed, parity, and individual animal history.