Both calculators turn a date into a due date for a pregnant dog. This page compares what each one asks for, how it counts, what it cites and what else the page offers, using only what is visible on each page.
Disclosure: CalcuPaw makes one of the calculators compared here. We only state what is visible on each page on the date above. Pages change; if something is out of date, tell us and we will correct it.
Side by side
| Feature | CalcuPaw | Omni Calculator (Dog Pregnancy Calculator) |
|---|---|---|
| Input | Date of mating, ovulation or LH surge (you choose which) | Date of mating |
| Due-date rule | About 63 days from ovulation, 65 ± 1 from the LH surge, 58 to 68 days from mating (Merck) | Mating date + 63 days; the page says the normal range is 58 to 68 days |
| Window shown | Due date plus earliest and latest normal dates | Due date and days remaining; the FAQ suggests adding 58 and 68 days for bounds |
| Sources on the page | Merck Veterinary Manual, linked | No formal citation list visible in the page text |
| Who reviewed it | CalcuPaw veterinary review team (names not published) | Named author and reviewers; no veterinarian is named on the page |
| Extra content | Week-by-week and signs guides, whelping checklist, heat-cycle calculator | Confirmation tests, litter size, false pregnancy, labour signs, supplies, feeding and puppy care notes, many related calculators |
When Omni Calculator may suit you better
- You want one site with hundreds of other calculators.
- You only know the mating date and want a quick answer plus a long explainer.
When CalcuPaw may suit you better
- You know the ovulation date or LH surge date, which narrows the window.
- You want the earliest and latest normal dates and a cited source.
Frequently asked questions
Do both calculators give the same due date from a mating date?
Yes. Both add 63 days to the mating date and describe 58 to 68 days as the normal range.
Which date should I use if I am unsure?
Use the mating date, and ask your vet to refine it with an ultrasound.
Source for the other tool
Omni Calculator (Dog Pregnancy Calculator), read 19 Oct 2026.