Precise and accurate porosity measurement is essential for characterization of porous materials. Considering Archimedes' principle based liquid displacement methods of measuring porosity we have developed an excellent modified micro-volumetric method of porosity measurement. Changes in the liquid level in a glass pipette after immersing and also removing the porous sample were recorded by using a digital camera and analysed by ImageJ® software. Results of porosity measurement through a micro-volumetric method were compared with micro-CT results. Bland–Altman analysis showed a much higher precision and accuracy for our micro-volumetric method (bias = −0.023, CI: ]−0.459, 0.413[, SD = 1.96 Ơ) compared to the micro-CT method (bias = 6.075, CI: ]−20.993, 33.142[, SD = 1.96 Ơ). Our highly precise and accurate micro-volumetric method of porosity measurement is particularly applicable to small ultra-light highly porous materials.