What's new
Until this update, only the calculator's default tab — the one that predicts a child's possible blood type from two parents — had a row of clickable preset chips underneath its input fields. Tap one, and it filled every dropdown for a common combination (say, A+ × B+) and ran the calculation immediately, skipping four manual dropdown selections.
The other two tabs, Compatibility Check and Find Missing Parent, didn't have that shortcut. Both modes ask for more fields than the child-prediction tab — Compatibility Check needs mother, father, and child; Find Missing Parent needs the child plus one known parent — so working through them by hand meant more clicking, not less. That gap has now been closed. Each of those two modes has its own preset row, positioned directly under its input fields, in the same style as the original.
The new Compatibility Check presets
Open the calculator, switch to the Compatibility check tab, and the chip row now sits right below the Child section, labeled "Common combinations to check." Tapping any of them fills all six dropdowns — mother's ABO and Rh, father's ABO and Rh, child's ABO and Rh — and triggers the calculation without needing to press the Calculate button separately.
The five combinations currently included:
- A+ × B+ checked against a child entered as AB−
- O+ × O+ checked against a child entered as A+
- O− × O− checked against a child entered as O−
- A+ × O+ checked against a child entered as B+
- AB+ × O+ checked against a child entered as AB+
Notice the mix: some of these presets land on "possible," others land on "not possible" — for instance, the O+ × O+ pairing checked against an A+ child is a case two type-O parents genetically cannot produce, so tapping that chip is a fast way to see what a flagged, not-possible result actually looks like, without typing in a real family's information to trigger it.
The new Find Missing Parent presets
Switch to the Find missing parent tab and the same pattern appears under the "Known parent" section: a "Common combinations" chip row. Each chip fills the child's ABO and Rh fields plus the known parent's ABO and Rh fields, then runs the reverse-lookup calculation.
| Child entered | Known parent entered |
|---|---|
| O+ | A+ |
| A− | O− |
| AB+ | A+ |
| B+ | O+ |
| O+ | AB+ |
The last row is a useful one to try first if you're new to this mode: an O+ child with an AB+ known parent. An AB parent has no O allele at all to pass down, so the child's O allele had to come entirely from the other, unknown parent — which narrows that unknown parent's ABO possibilities more tightly than most other combinations do. Tapping that chip is a fast way to see the tool work through a case where the logic isn't obvious at a glance.
Why this was worth adding
Our earlier guide on these two modes noted that the preset pattern existed only on the child-prediction tab, and flagged extending it to Compatibility Check and Find Missing Parent as a reasonable improvement for later — since those two modes involve at least as many dropdown fields as the original tab, and arguably invite more repeat use (checking several family records back-to-back, for example). That gap is now closed on both tabs.
The practical benefit is small per click but adds up with repetition: instead of six manual dropdown selections to test a Compatibility Check scenario, or four to test a Find Missing Parent scenario, a single tap loads a realistic example and shows the full result — genotypes, verdict, and (where relevant) the shortlist of possible types — immediately. That's particularly handy for getting a feel for how either mode behaves before typing in an actual family's blood types.
See the new one-tap presets on Compatibility Check and Find Missing Parent for yourself.
Try the Updated Calculator →