Enter your dog’s progesterone test results to find her likely LH surge (day 0), ovulation, best breeding days and due date.
Disclaimer: Labs and dogs vary. This tool explains typical ranges only. Your veterinarian should interpret progesterone results and plan breeding.
| Progesterone (ng/mL) | What it usually means |
|---|---|
| Below about 1.5 | Baseline. The LH surge hasn’t happened yet. Keep testing. |
| About 1.5–2.5 | LH surge range. This is usually counted as day 0. |
| About 4–10 | Typical range at ovulation, 2–3 days after the LH surge. |
| Above 5 on a recheck | Confirms ovulation has happened. |
| 4–20+ | Range during the fertile period. |
Source: Merck Veterinary Manual. If your lab reports nmol/L, divide by 3.18 to get ng/mL. The calculator does this for you.
It finds the first result that has risen to about 1.5 ng/mL or more. If that result is in the LH surge range (1.5–2.5), that test day becomes day 0. If the first raised result is already higher, the calculator works backwards to estimate day 0 and tells you it’s an estimate.
From day 0 it shows ovulation (days 2–3), when the eggs mature (days 4–6), the best breeding days for your breeding type, and the due date, 64–66 days after the LH surge.
Breeding is timed from the LH surge (about 1.5–2.5 ng/mL), not from one number. Natural breeding is usually best on days 3–6 after the surge, when progesterone is often well above 5 ng/mL. Ask your vet to set the exact plan.
About 2–3 days. The eggs then need 2–3 more days to mature before they can be fertilized.
Very accurate. Dogs give birth 64–66 days after the LH surge, compared with 58–72 days when counting from a mating date.
Some labs use nmol/L. Choose nmol/L in the calculator, or divide by 3.18 to convert to ng/mL.
Due date, pregnancy week and a dated timeline from the mating date.
Open calculator →Predict her next heats and the typical fertile days.
Open calculator →Best breeding days from the first day of her heat.
Open calculator →Countdown to labor, prep checklist and a puppy delivery log.
Open calculator →The right box size for your dog, with a layout diagram.
Open calculator →Check each newborn puppy is gaining weight normally.
Open calculator →Weaning, deworming, vaccines and go-home dates.
Open calculator →How many puppies to expect for her size.
Open calculator →Sources: Merck Veterinary Manual – Breeding Management of Dogs and Cats. This page is general information, not veterinary advice. Read our veterinary disclaimer.