delivered the Opinion of the Court.
This is an appeal from a decision of the workers’ compensation court, Billings, that claimant sustained a 12% permanent partial disability and awarding a lump sum payment in the amount of $2,431.20.
Virginia Flake, claimant and appellant, is a licensed practical nurse. She suffered an injury to her lower back in the course of her employment at St. Vincent’s Hospital in Billings on March 3, 1974. Prior to her injury, she was employed part-time, working an average of three eight hour days per week. The record reveals claimant worked one full forty hour week just prior to her injury.
Following the injury, claimant continued to work until March 30, 1974, when the pain of the injury forced her to discontinue her work. Dr. D. R. Huard performed a laminectomy on claimant in August 1974. The Workers Compensation Division paid all bills and lost wages during the period of claimant’s nonemployment.
On November 18, 1974, claimant resumed work at St. Vincent’s. She was unable to do lifting because of the injury. However she was able to work three to four days per week and has, in fact, worked several forty hour weeks subsequent to the injury. Her wages have increased approximately eighty cents per hour, primarily due to across the board cost of living increases, so she makes somewhat more money now than before the injury.
On August 29, 1974, Dr. Huard submitted a report stating:
“ * * * I believe there is a partial permanent impairment. This *129following result of laminectomy would be 20% of her spine, which converts to 12% of the man as a whole. * * *”
The insurance carrier for St. Vincent’s, defendant and respondent Aetna Life & Casualty Company concluded the 12% impairment factor .limited its liability under the Workers’ Compensation Act to 12% or 60 of the possible 500 weeks of maximum benefit. Multiplying 60 weeks by the weekly compensation rate of $40.52 yielded $2,431.20, which sum was offered to claimant.
Claimant rejected the offer and, on September 4, 1975, sought a determination before the workers’ compensation court. During the hearing of November 5, 1975, pursuant to claimant’s petition, claimant submitted evidence of her inability to perform certain types of work, such as lifting, as a direct result of her injury. The court, by its findings of fact and conclusions of law dated August 23, 1976, accepted the carrier’s computation of $2,431.20, upon a finding of no substantial loss of earning capacity, based upon claimant’s work records and the 12% impairment rating. Claimant appeals the court’s conclusions.
The issue presented by this appeal is whether the workers’ compensation court erred in arriving at a 12% permanent partial disability rating, given the facts of record. We hold it did not.
Claimant contends the court should not have determined disability solely upon the basis of the doctor’s medical impairment rating but, rather, that disability should be computed upon a consideration of “loss of earning capacity”. In making such computation, the court should properly evaluate the disability in view of claimant’s age, education, work experience, pain and disability, actual wage loss, and loss of future earning ability. Here, claimant’s inability to perform more than three or four days of work should be considered strong evidence of a loss of earning capacity. In this regard, claimant submits the Workers’ Compensation Act should be liberally construed in favor of recovery.
Respondent, however, stresses that claimant is presently working at least as- many hours and, in fact, is earning more after than before the injury, therefore there being no actual wage loss there is *130no loss of earning capacity. Claimant sustained a “bodily functional impairment” only, fully compensable by the settlement offered by respondent insurance carrier. The court properly based its award on the percentage of such impairment, this being the only substantive evidence of disability.
Claimant’s petition for workers’ compensation benefits proceeded under and is governed by the Workers’ Compensation Act, section 92-703.1, R.C.M.1947. This section provided prior to amendment in 1975:
“Compensation for injuries causing partial disability. Weekly compensation benefits for injury producing partial disability shall be sixty-six and two-thirds percent (66%%) of the difference between the wages received at the time of the injury and the wages the injured employee is capable of earning thereafter, subject to a maximum compensation of sixty dollars ($60.00) a week.
Section 92-703.1 “* * * bases the benefit upon actual loss of earning capacity resulting from the injury * * McAlear v. Arthur G. McKee & Co., 171 Mont 462, 558 P.2d 1134 (1976). It is manifest from a reading of section 92-703.1 that the test for such loss of earning capacity under the Workers’ Compensation Act is “the difference between the wages received at the time of the injury and the wages the injured employee is capable of earning thereafter * * *.” Also see: Olson v. Manion's, Inc., 162 Mont. 197, 202, 510 P.2d 6, 7(1973).
Claimant relies on decisions of this Court adopting the “loss of earning capacity” test. Shaffer v. Midland Empire Packing Co., 127 Mont. 211, 259 P.2d 340 (1953); Lind v. Lind, 142 Mont. 483, 385 P.2d 83 (1963). Claimant draws support primarily from the related rule emerging from such cases, that loss of earning power as a result of an injury is not necessarily proportional to bodily functional impairment. It is argued that to equate a percentage bodily functional impairment rating with a percentage disability rating for purposes of compensation under section 92-703.1, is to make wholly arbitrary the concept of “compensable disability”.
*131While we agree a small percentage of bodily functional impairment can result in a substantial loss of earning capacity and a greater compensation award in some cases, the evidence adduced at the hearing in the instant case leads to the opposite conclusion. Claimant was shown to be working at least as many hours after the injury as before. The fact claimant may have worked more hours, earned more pay, or been promoted in her employment had it not been for the injury, is immaterial to a determination of compensable disability especially where, as here, the record is devoid of evidence in support of such a conclusion. Olson v. Manion’s, Inc., supra. The salient fact remains claimant was a part-time employee before and after the injury. To base an original compensation award upon any other criterion would be to do violence to the literal language of section 92-703.1.
Finally, we note the medical report submitted by Dr. Huard was the sole evidence in the record substantiating the percentage of claimant’s impairment. We find the workers’ compensation court had no alternative, based upon the facts in the record, than to ground the award on the impairment rating in the light of claimant’s work records and, in so doing, accepting the settlement figure offered by respondent insurance carrier.
The decision of the workers’ compensation court is affirmed.
MR. JUSTICE HASWELL concurs. MR. CHIEF JUSTICE HATFIELD concurs in the result, but not in all the discussion.