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How is the payback period calculated, and what are its strengths and weaknesses as an appraisal method?

Calculate the payback period for a project and evaluate its usefulness as an investment appraisal method

A focused answer to the H2 Principles of Accounting outcome on the payback period. Calculating payback with even and uneven cash flows, interpolating within a year, and the strengths and limitations of the method.

Generated by Claude Opus 4.89 min answerUpdated 2026-06-06

Reviewed by: AI editorial process; not yet individually human-reviewed

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What this dot point is asking
The answer
Examples in context
Try this

What this dot point is asking

SEAB wants you to calculate the payback period of a project and to evaluate its usefulness as an appraisal method. Payback is the simplest of the capital-investment techniques and a common first screen for projects. The central insight is that payback measures how quickly the initial outlay is recovered from net cash inflows, which captures liquidity and risk, but it ignores both what happens after payback and the time value of money.

The answer

What payback measures

The payback period is the time taken for a project's cumulative net cash inflows to equal its initial cash outlay. The shorter the payback, the sooner the money is recovered and the lower the exposure to future uncertainty. Businesses often set a maximum acceptable payback and reject projects that exceed it.

Even cash flows

When inflows are equal each year, payback is a simple division:

\text{Payback} = \frac{\text{initial outlay}}{\text{annual net cash inflow}}

For example, a $\$ 100,000 $project returning$ \ $25\,000$ a year pays back in $\dfrac{100\,000}{25\,000} = 4$ years.

Uneven cash flows

When inflows vary, accumulate them year by year until the outlay is recovered, then interpolate within the final year:

\text{Payback} = \text{full years} + \frac{\text{outlay still to recover at the start of the year}}{\text{cash inflow during that year}}

This part-year fraction assumes cash flows arise evenly through the year, a simplification, since cash may actually arrive in lumps.

Strengths and weaknesses

Strengths	Weaknesses
Simple to calculate and understand	Ignores cash flows after payback
Emphasises liquidity (fast cash recovery)	Ignores the time value of money
Reduces risk by favouring near-term returns	Gives no measure of overall profitability

Payback is therefore a useful first filter, especially when liquidity matters, but it should be combined with a method like net present value that accounts for profitability and timing.

Worked example

A machine costs $\$ 200,000 $and is expected to generate net cash inflows of$ \ $60\,000$ , $\$ 80,000 $,$ \ $70\,000$ and $\$ 50,000$ over four years. Calculate the payback period.

Step 1: Build the cumulative cash flow

Year	Inflow	Cumulative
1	60,000	60,000
2	80,000	140,000
3	70,000	210,000
4	50,000	260,000

Step 2: Find the year payback occurs

By the end of year 2, $\$ 140,000 $is recovered; by the end of year 3,$ \ $210\,000$ . The outlay of $\$ 200,000$ is recovered during year 3.

Step 3: Interpolate within year 3

At the start of year 3, $200\,000 - 140\,000 = \$ 60,000 $is still to be recovered, and year 3 brings in$ \ $70\,000$ .

\text{Fraction of year 3} = \frac{60\,000}{70\,000} \approx 0.86 \text{ years}

Step 4: State the payback

\text{Payback} = 2 + 0.86 \approx 2.86 \text{ years (about 2 years 10 months)}

The project recovers its cost in under three years. Whether that is acceptable depends on the firm's target payback; the figure alone is only a screening result.

Examples in context

Example 1. A liquidity-conscious small firm. A small business with limited cash sets a maximum payback of three years, because it cannot afford to wait long to recover its investment. A project paying back in $2.5$ years is accepted and one paying back in $4$ years rejected, regardless of long-term profit. Here the payback method's focus on fast cash recovery directly serves the firm's real liquidity constraint.

Example 2. Where payback misleads. Project A pays back in two years then stops earning; Project B pays back in three years but generates large cash flows for ten years. Payback ranks A above B, yet B is far more profitable overall. This shows the danger of relying on payback alone: it ignores everything after the payback point, which is exactly what net present value captures.

Try this

Q1. A project costs $\$ 90,000 $and returns$ \ $30\,000$ a year. Find the payback period. [2 marks]

Cue. Even flows: $\dfrac{90\,000}{30\,000} = 3$ years.

Q2. Inflows are $\$ 40,000 $,$ \ $50\,000$ , $\$ 60,000 $; the outlay is$ \ $120\,000$ . Find the payback period. [3 marks]

Cue. Cumulative $\$ 90,000 $by year 2;$ \ $30\,000$ of year 3's $\$ 60,000 $needed, so payback$ = 2 + \dfrac{30,000}{60,000} = 2.5$ years.

Q3. State one strength and one weakness of the payback method. [2 marks]

Cue. Strength: simple and emphasises liquidity by favouring fast cash recovery. Weakness: ignores cash flows after payback and the time value of money.

Exam-style practice questions

Practice questions written in the style of SEAB exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.

Original7 marksA project costs

\

120\,000

and generates net cash inflows of

30\,000

\

40\,000

,

50\,000

and

\

60\,000$ in years 1 to 4. (a) Calculate the payback period. (b) State the assumption made about cash flows within a year.

Show worked answer →

Accumulate the cash inflows until the $\$ 120,000$ outlay is recovered.

Year	Cash inflow	Cumulative
1	30,000	30,000
2	40,000	70,000
3	50,000	120,000
4	60,000	180,000

By the end of year 3 the cumulative inflow is exactly $\$ 120,000$, so the payback period is 3 years.

(If the outlay were, say, $\$ 100,000 $: recovered$ \ $70\,000$ by year 2, needing $\$ 30,000 $of year 3's$ \ $50\,000$ , so payback $= 2 + \dfrac{30\,000}{50\,000} = 2.6$ years.)

(b) The interpolation within a year assumes cash inflows accrue evenly throughout the year, so a part-year fraction can be taken; in reality cash may arrive unevenly.

Markers reward the cumulative cash flow table, a payback of $3$ years, and the even-cash-flow assumption for part-year interpolation.

Original6 marksExplain two advantages and two disadvantages of the payback period as a method of investment appraisal.