PH Poh

pH / pOH / hydronium / hydroxide converter at 25 °C, plus a Henderson-Hasselbalch buffer calculator.

pH section

Edit any of pH, pOH, [H⁺], [OH⁻]; the others update via K_w = 10⁻¹⁴ and pH + pOH = 14.

Buffer

pH = pK_a + log₁₀([A⁻]/[HA]). The buffer is effective within pK_a ± 1; the calculator flags out-of-range setups.