Find the right diaper size for your baby's weight — with US and EU/international size charts side by side.
No — sizing varies between brands, and sometimes between product lines from the same brand. Use this calculator as a starting point, then check the specific brand's own size chart on the package.
Go by fit, not just the number on the scale. Red marks, gaps at the legs, or frequent leaks are signs to size up. Tabs that overlap a lot, or a diaper that sags and falls, are signs to size down.
Many babies move up a size every 2–3 months during the first year, though every baby grows differently — some stay in one size for longer, others move faster during growth spurts.
Some parents size up by one for overnight to handle heavier overnight wetting, but a diaper that's too loose can leak worse than one that fits well. Try their current size with an overnight-rated diaper first.
Weight is far more reliable — babies grow at very different rates, so a diaper sized by age alone may already be too small (or too big) for an individual baby's actual weight.