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Pick a calculator, paste the snippet, you’re done. The widget is responsive, lazy-loaded, and links back to the full version on willthey.baby. No tracking, no upsells, no account required.

Due Date Calculator

Calculate your baby's due date with cycle-length adjustment. Naegele's rule, done honestly.

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<iframe src="https://willthey.baby/embed/due-date" width="100%" height="720" frameborder="0" loading="lazy" title="Due Date Calculator — Will They" style="border:0;max-width:100%;"></iframe>
<p style="font-size:12px;color:#666;margin:6px 0 0"><a href="https://willthey.baby/due-date">Due Date Calculator</a> by <a href="https://willthey.baby">Will They</a></p>

Ovulation Calendar

Six months of fertile windows, periods, and ovulation days at a glance.

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<iframe src="https://willthey.baby/embed/ovulation-calendar" width="100%" height="900" frameborder="0" loading="lazy" title="Ovulation Calendar — Will They" style="border:0;max-width:100%;"></iframe>
<p style="font-size:12px;color:#666;margin:6px 0 0"><a href="https://willthey.baby/ovulation-calendar">Ovulation Calendar</a> by <a href="https://willthey.baby">Will They</a></p>

Eye Color Predictor

Polygenic eye-color predictor with optional grandparents — far better than the 1907 Punnett square.

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<iframe src="https://willthey.baby/embed/eye-color" width="100%" height="820" frameborder="0" loading="lazy" title="Eye Color Predictor — Will They" style="border:0;max-width:100%;"></iframe>
<p style="font-size:12px;color:#666;margin:6px 0 0"><a href="https://willthey.baby/eye-color">Eye Color Predictor</a> by <a href="https://willthey.baby">Will They</a></p>

Baby Name Popularity

See how popular any baby name has been since 1880, using the official SSA dataset.

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<iframe src="https://willthey.baby/embed/name" width="100%" height="760" frameborder="0" loading="lazy" title="Baby Name Popularity — Will They" style="border:0;max-width:100%;"></iframe>
<p style="font-size:12px;color:#666;margin:6px 0 0"><a href="https://willthey.baby/name">Baby Name Popularity</a> by <a href="https://willthey.baby">Will They</a></p>

Formula Feeding Calculator

AAP-aligned formula amounts: ounces per day, per feeding, and how often, by baby weight + age.

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<iframe src="https://willthey.baby/embed/formula" width="100%" height="720" frameborder="0" loading="lazy" title="Formula Feeding Calculator — Will They" style="border:0;max-width:100%;"></iframe>
<p style="font-size:12px;color:#666;margin:6px 0 0"><a href="https://willthey.baby/formula">Formula Feeding Calculator</a> by <a href="https://willthey.baby">Will They</a></p>

hCG Doubling Time Calculator

Beta hCG doubling time with Kadar 1981 and Barnhart 2004 reference ranges.

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<iframe src="https://willthey.baby/embed/hcg" width="100%" height="720" frameborder="0" loading="lazy" title="hCG Doubling Time Calculator — Will They" style="border:0;max-width:100%;"></iframe>
<p style="font-size:12px;color:#666;margin:6px 0 0"><a href="https://willthey.baby/hcg">hCG Doubling Time Calculator</a> by <a href="https://willthey.baby">Will They</a></p>

The fine print

  • Free to use on any site, commercial or otherwise.
  • Please keep the “Powered by Will They” attribution intact — it’s how we keep this free.
  • No tracking pixels in the iframe. We do log a referrer-only request server-side to know which calculators are popular.
  • Need a different calculator embeddable? Email hello@willthey.baby.