Free tool

Baby Size by Week Calculator

Find out how big your baby is this week — from a poppy seed at week 4 to a watermelon at week 40 — using your gestational week or estimated due date.

Week
20
About the size of a
Banana
Approx. length
16.6 cm

Baby size comparisons are a fun, approximate way to visualise growth — actual measurements vary between individual pregnancies.

How to use this calculator

Choose your preferred input mode: enter your gestational week directly (weeks 4–40) using the dropdown, or enter your estimated due date and the calculator will work out your current week automatically. The result shows the week number, a fruit or vegetable comparison, and an approximate crown-to-rump length in centimetres.

Understanding your result

Baby size comparisons are a widely used, enjoyable way to visualise how your baby is growing throughout pregnancy. The sizes shown are based on average crown-to-rump and crown-to-heel lengths for each gestational week. Individual babies vary in size — some will be larger or smaller than the comparison suggests, and that is entirely normal. For clinical growth monitoring, your midwife or doctor will use ultrasound measurements.

Disclaimer

Menstrual cycles, fertility, and pregnancy vary significantly between individuals. Results from this tool are statistical estimates and may not reflect your personal health. This is not medical advice, a diagnosis, or a substitute for professional care. If you have concerns about your pregnancy or reproductive health, consult a gynaecologist or healthcare provider.

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Track your pregnancy week by week, log appointments, weight and scans, and see everything in one place with OptiAI.

Frequently asked questions

How accurate are baby-size comparisons?

Fruit and vegetable comparisons are a fun, approximate way to visualise your baby's growth — they are not precise measurements. Actual baby size varies between individual pregnancies. For accurate measurements, ultrasound biometry (CRL, BPD, FL) performed by a sonographer is the clinical standard.

Is this medical advice?

No. This calculator provides estimates for informational purposes only. Always consult a qualified healthcare professional before making decisions about your health.

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