According to Canada Life Group Insurance, only 19% knew that they would receive between £70 and £80 each week although 20% claimed that they would require at least £300 and 17% that they would need £425.
A mere 4% of employees said they could survive on less than £100 each week.
Marion Ware, head of marketing at Canada Life Group Insurance, said: "These results highlight that many consumers would not be able to maintain their current lifestyles if they were deemed unable to work and had to rely purely on incapacity benefits. With the proposed changes to Welfare Reform due to come into play in October, the assessment for the new Employment and Support Allowance is set to be a lot stricter.
"Therefore, when applying for state benefit, consumers may find it a lot harder to meet the eligibility criteria and receive maximum benefits," she added.
Employees are woefully ignorant about incapacity benefits
Nearly nine out of 10 (87.5%) employees have no idea how much money they would get from the Government if they were away from work due to long-term illness or injury.