Is hard-boiled Safe for Kidney Stones? (Safe)
mg oxalate
per serving
Serving: 2 large (100 g)
Verdict: 🟢 Safe
Per 100g: 0 mg
Data: Harvard T.H. Chan SPH (2024)
The bottom line for hard-boiled: Safe (🟢), with 0 mg oxalate per serving — comfortably below the 25 mg safe cutoff. There's no need to limit it. Just keep your usual kidney stone basics in place: water throughout the day and calcium-rich foods at meals.
Putting hard-boiled in context: it lands well below the category average of 3 mg. In the database, 95% of dairy & eggs (87 of 91) fall in the 🟢 Safe group (under 25 mg oxalate/serving). The typical dairy & eggs here averages 3 mg oxalate per serving, so hard-boiled runs 100% below that baseline. That places it among the lower-oxalate options in its category. Why this matters: the gap between two Safe foods can be wide — one may hold 5 mg oxalate while another sits at 24 mg. The lower one leaves more room in your day. See all dairy & eggs rated Safe for a full side-by-side.
Why does the safe threshold matter?
The 25 mg per serving threshold is based on clinical guidance for kidney stone patients. Harvard's lab data (2024) provides the most reliable oxalate measurements available — no database estimates, direct lab analysis. For context, hard-boiled measures 0 mg per 2 large, rated Safe.
Can I eat this food every day?
For Safe foods (under 25 mg/serving), daily use is generally fine. Caution and Avoid foods work better as occasional items — rotate them with safer options so no single high-oxalate food becomes a habit. For hard-boiled, the measured oxalate value is 0 mg per 2 large (Safe).
Where does the oxalate data come from?
Harvard T.H. Chan School of Public Health (2024) via the OHF database. These are direct laboratory measurements — the most reliable oxalate data available for food. For context, hard-boiled measures 0 mg per 2 large, rated Safe.
Should I also check sodium and calcium?
Yes — kidney stone risk isn't just about oxalate. High sodium increases urinary calcium (a stone promoter). Adequate dietary calcium (from food, not supplements) actually binds oxalate in your gut. Check the food's full nutrition page for the complete picture. For hard-boiled, the measured oxalate value is 0 mg per 2 large (Safe).