Know your dog's progesterone levels? Find out exactly when your puppies will be born. Enter each test as it comes in, and the calculator finds the day progesterone crosses the ovulation threshold and projects 63 days forward.
Built for veterinary practice — not a replacement for clinical judgementEach bitch's readings are saved separately so you can track multiple cases at once.
Every patient and reading is already saved automatically on this device. Export a backup regularly so records survive a browser reset, or move them to another computer.
Add each test as results come in — typically every 2–3 days from the first sign of proestrus bleeding. Enter in whichever unit your machine reports; the other is calculated automatically.
Optional — recording the mating date(s) helps cross-check the progesterone-based estimate against the traditional mating-based range.
Based on the day progesterone first reaches this clinic's Minividas-calibrated ovulation threshold (20–25 nmol/L).
A quick refresher on interpreting the canine progesterone curve, since reproduction work isn't part of everyone's regular caseload.
Progesterone rises from baseline to the ovulation threshold over roughly a week, but the rate of rise varies a lot between individual bitches. A single reading only tells you where she is today — testing every 2–3 days from the first sign of proestrus bleeding lets you catch the actual day the threshold is crossed, which is what the due-date calculation depends on.
| Stage | ng/mL | nmol/L | What it means |
|---|---|---|---|
| Baseline | <1.0 | <3.2 | Anoestrus or early proestrus. Too early to plan mating. |
| Rising | 1.0–2.4 | 3.2–7.6 | Approaching the LH surge. Increase testing frequency. |
| LH surge | 2.5–4.9 | 8.0–19.9 | LH surge has likely just occurred. Ovulation follows in ~2 days. |
| Ovulation | ~6.3–7.9 | 20–25 | At or past this clinic's ovulation threshold. This is Day 0 for the 63-day count. |
Note: the 20–25 nmol/L ovulation figure is calibrated specifically to this clinic's Minividas machine against real case data, and is what this calculator uses. It runs a little higher than the commonly cited textbook figure of ~5.0 ng/mL (~15.9 nmol/L) — a reminder that absolute progesterone values genuinely differ between analysers, so a threshold from a different machine or lab shouldn't be applied here without re-checking it against this equipment.
Sperm can survive in the reproductive tract for several days, and eggs need roughly 2 days after ovulation to mature before fertilisation is possible — so the mating date and the fertilisation date are rarely the same day. Whelping is far more consistent when counted from ovulation (63 ± 1 day) than from mating (a much wider 58–68 day range from first mating), which is why progesterone timing is worth the extra testing.
1 ng/mL × 3.18 = nmol/L. This is the standard molar conversion for progesterone (based on its molecular weight of 314.46 g/mol) and is what this calculator uses throughout. If a result looks like it doesn't match this conversion, double-check which unit the machine actually reported.
This calculator is built for the pre-mating ovulation-timing window. Later in pregnancy, progesterone behaves differently: it climbs to a high plateau (roughly 10–80 ng/mL) for most of gestation, then drops sharply in the last day or two before whelping — a fall below about 2 ng/mL (≈6 nmol/L) close to term is a reliable sign that whelping will begin within 24–48 hours. Don't apply the ovulation-threshold logic on this page to a late-pregnancy reading; it's a different phase of the curve.