| Cover | Oct. 21, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Oct. 21, 2021 |
| Entity File Number | 000-30414 |
| Entity Registrant Name | ALR TECHNOLOGIES INC. |
| Entity Central Index Key | 0001087022 |
| Entity Tax Identification Number | 88-0225807 |
| Entity Incorporation, State or Country Code | NV |
| Entity Address, Address Line One | 7400 Beaufont Springs Drive |
| Entity Address, Address Line Two | Suite 300 |
| Entity Address, City or Town | Richmond |
| Entity Address, State or Province | VA |
| Entity Address, Postal Zip Code | 23225 |
| City Area Code | (804) |
| Local Phone Number | 554-3500 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Shares |
| Trading Symbol | ALRT |
| Security Exchange Name | NONE |
| Entity Emerging Growth Company | false |
