Early years 
Service as priest 
He went on to become a clergyman, serving as a curate at Constantine, Kerrier (1779–83) and afterwards at Greens Norton, near Towcester. In 1789 he was entered as a 'ten-year man' at Trinity College, Cambridge, and eventually graduated BD in 1800. In 1790 he was presented to the vicarage of Potterspury in Northamptonshire. On 10 November 1794 he married Anne Brock of North Tawton. He founded the village school in Potterspury: today the John Hellins Primary School bears his name.
Recognition of his scientific contribution 
His mathematician and astronomical learning was noted. He became a Fellow of the Royal Society in 1796. Two years later (1798), he was awarded the Copley Medal largely for his paper on computing the perturbations of planets.
Analytical Institutions 
He supervised the translation from Italian of the Instituzioni analitiche ad uso della gioventù italiana by Maria Gaetana Agnesi, which was published in 1801 by Taylor and Wilks, London as Analytical Institutions in Four Books
Davies Gilbert's eulogy 
One of those extraordinary men, who, deprived of early advantages, have elevated themselves, by the force of genius of industry, to a level above most persons blessed with regular education. [...]
In 1787 he edited The Young Algebracist's Companion. In 1788, he published Mathematical Essays, on several subjects and in 1802 in two volumes, The Analytical Institutions, originally written in Italian, by Maria Gaetana Agnesi, translated by John Colson. Taking orders, Hellins was for some time curate of Constantine in Cornwall and, afterwards, of Greens Norton, Northamptonshire, but in 1790 he was presented by the Earl Bathurst to the vicarage of Potterspury in Northamptonshire. He was elected a Fellow of the Royal Society in 1796, and in 1800 took the degree of B.D. at Trinity College, Cambridge.
Hellins at one time computed the Nautical Almanac. He later assisted at Greenwich and, furnished William Windham with calculations and tables on which to base his new military system, as Minister of War, in 1806.
Hellins applied himself also branches of pure mathematics. Nine communications from him appeared in the Philosophical Transactions:
- On the summation of series.
- On the conversion of slowly-converging series into others of swifter convergency.
- On their application to the calculation of logarithms, and to the verifing of circular area.
- On the roots of equations.
And in 1798,
- On method of computing with increased facility the planetary perturbations.
For the last he was honoured with the Copley Medal.
- On Mr. Wales' Method of finding the Longitude, Vol. 6. p. 413.
- On Bishop Horsley's Mathematical Treatises, Vol. 21. p. 272.
- On Donna Agnesi's Analytical Institutions, of which he superintended the publication, Vol. 23. p. 143; Vol. 24. p. 653 ; and 25. p. 141.
- On Keith's  Trigonometry, Vol. 31. p. 489.
- On F. Baily's work, on the Doctrine of Interest and Annuities, Vol. 38. p. 622, and Vol. 43. p. 502.
When the first series of the British Critic closed, the connection with Hellins with the work is supposed to have ceased.
Hellins retired to a small living in Northamptonshire. He married Miss Brock, a Devonshire lady, who survived him but a short time, and by whom he left an only son.
He died in Potterspury 5 April 1827, leaving one son by his wife Anne. In the North Aisle of the parish church of St. Nicholas is a small tablet of white marble, inscribed:
" In Memory of The REVD. JOHN HELLINS, B.D. & F.R.S./ upwards of 36 years Vicar of this parish, who died April 5th 1827/ aged 78 years./ of ANNE HELLINS his widow, who died June 3rd 1827. Aged 72.
- John Hellins, 1829–87, clergyman and entomologist: Darwin correspondence project database, which lists this Hellins as one of Charles Darwin's correspondents. It is not known whether the two John Hellinses were related.
- The transcribed Burial Records of Potterspury, at http://www.potterspury.org.uk/fhs/pr/pury/burial_h.htm , show his age at death as 78.
- R. E. Anderson, ‘Hellins, John (d. 1827)’, rev. Adrian Rice, Oxford Dictionary of National Biography, Oxford University Press, 2004; online edn, May 2008, accessed 13 Dec 2009
- . An early scientific paper was: "Theorems for Computing Logarithms." By the Rev. John Hellins; Communicated by the Rev. Nevil Maskelyne, D. D., F. R. S. and Astronomer Royal,in Philosophical Transactions Series I,(1780), volume 70, pages 307-317 [Referred to by Smithsonian/NASA ADS Astronomy Abstract Service.
- Venn, J.; Venn, J. A., eds. (1922–1958). "Hellins, John". Alumni Cantabrigienses (10 vols) (online ed.). Cambridge University Press.
- The school website includes a portrait of John Hellins:John Hellins Primary School at http://www.johnhellinsprimary.ik.org/ > About us > Reverend John Hellins
- A digitised scan of the Analytical Institutions is available at Google Books. Hellins signs the Editor's Advertisement September 29, 1801, Potter's-Pury.
- The Gentleman's Magazine 1828, Volume 98 (New series No. 21) page 181 (Obituary section).
- The British Critic: A conservative review journal, launched in 1793. See ODNB article: ‘Beloe, William (1758–1817)’
- William Wales: see ODNB article: ‘Wales, William (bap. 1734, d. 1798)’.
- Thomas Keith see ODNB article ‘Keith, Thomas (bap. 1759, d. 1824)’
- The first series of the British Critic closed in 1813.
- Potterspury village website.
- Photograph of his grave
Further reading 
- John Hellins: R. E. Anderson, ‘Hellins, John (d. 1827)’, rev. Adrian Rice,Link to article in ODNB accessed 30 May 2007.
- William Wales: E. I. Carlyle, ‘Wales, William (bap. 1734, d. 1798)’, rev. Derek Howse, Link to article in ODNB accessed 20 Aug 2007
- Thomas Keith: W. A. J. Archbold, ‘Keith, Thomas (bap. 1759, d. 1824)’, rev. Ruth Wallis, Link to article in ODNB, accessed 20 Aug 2007
- William Beloe: Antonia Forster, ‘Beloe, William (1758–1817)’, Link to article in ODNB accessed 21 Aug 2007. Beloe was one of the proprietors of The British Critic.