How-to
How to Use the Cost of Delay Calculator
A plain walkthrough to see the illustrative cost of waiting: enter your amount and rate, pick a delay window, and compare “start now” vs “start later.”
Published: December 22, 2025 · Updated: December 22, 2025 · By FinToolSuite Editorial
Open the calculator
Run your own start-now vs start-later scenarios in a few clicks.
Quick answer
- Enter your lump sum (or starting amount) and an illustrative return assumption.
- Set the delay window (months/years) and your total horizon.
- Compare “start now” vs “start later” to see the estimated opportunity cost.
What the calculator measures
The cost of delay is an illustrative opportunity cost: the difference between starting now and starting after a chosen delay, using the same return assumption and horizon. It’s a model based on your inputs, not a promise.
Disclaimer
Educational purposes only; not financial advice. Examples are illustrative; real returns vary and investments can go down as well as up. Fees, taxes, inflation, and provider rules vary by country and account type.
Inputs explained
Lump sum / starting amount
The amount you’re modeling today. Example: £1,000–£20,000.
Common mistake: leaving it blank or adding commas that break the number.
Return assumption (annual %)
Illustrative annual rate. Example ranges: 3%, 5%, 7%.
Common mistake: typing “5” as “0.05” or mixing APR/APY.
Delay window
How long you wait before starting. Example: 6–24 months.
Common mistake: mixing months and years or entering “0.5” when the field expects months.
Time horizon
Total period you want to model. Example: 10–20 years.
Common mistake: comparing scenarios with different horizons, which skews the gap.
Compounding frequency (if shown)
How often growth is applied (e.g., yearly vs monthly). Keep it the same across scenarios for fair comparisons.
Common mistake: switching frequency between scenarios while comparing delay.
Contributions
If your version doesn’t support contributions, keep this to £0 and focus on the lump sum and delay.
Common mistake: assuming monthly contributions are included when the tool models lump sums only.
Step-by-step walkthrough (example)
Example inputs: £5,000, 5% return assumption, 12-month delay, 15-year horizon.
- Open the Cost of Delay Calculator.
- Enter the starting amount: £5,000.
- Enter the rate: 5 (as a percent, not 0.05).
- Set the delay window: 12 months.
- Set the total horizon: 15 years.
- Run the calculation to see “start now” vs “start after delay” and the estimated opportunity cost.
Try this exact example: launch the calculator.
How to read the results
- Start now: projected value if you begin immediately.
- Start after delay: projected value if you wait for the chosen window.
- Estimated opportunity cost: the difference between the two projections.
- Charts (if shown) visualize how the gap opens over time.
What to look for: the gap size, how rate changes affect the gap, and how longer horizons widen differences.
Saving scenarios
A scenario is a set of inputs you want to revisit. Save after running, and give clear names such as “Start now 5%” or “Delay 12m 5%”. If your version stores scenarios locally, they stay on your device.
Comparing scenarios side-by-side
Use one variable at a time for clean comparisons:
- Scenario A: Start now.
- Scenario B: Delay 6 months (same rate and horizon).
- Scenario C: Delay 12 months (same rate and horizon).
Keep rate and horizon constant; change only the delay. See more side-by-sides in the cost of delay examples.
Common pitfalls
- Using 0.05 instead of 5 for the rate (or vice versa).
- Mixing months and years for the delay window.
- Changing multiple variables at once, making comparisons unclear.
- Treating the rate as guaranteed.
- Ignoring fees, taxes, or inflation when thinking about net outcomes.
- Comparing scenarios with different horizons.
More help: cost of delay common mistakes and cost of delay calculator FAQ.
FAQ
What does “cost of delay” mean?
It’s an illustrative opportunity cost: the estimated difference between starting now and starting after a delay.
What return assumption should I use?
Use illustrative ranges (e.g., 3%, 5%, 7%) and compare low/base/high cases. Avoid treating any rate as guaranteed.
Does a small delay matter?
Short delays reduce growth time. The impact depends on rate, horizon, and amount—run both scenarios to see the gap.
Why do results change so much with the rate?
Higher rates increase growth potential, so the difference between start-now and start-later widens as the rate rises.
Are results guaranteed?
No. They are estimates based on your inputs; real returns vary and can be negative.
Does inflation matter?
Yes—higher inflation can reduce real purchasing power. Adjust assumptions if you want to see different net outcomes.
Can I compare multiple delays?
Yes. Save scenarios (e.g., 0 months, 6 months, 12 months) and view them side-by-side.
Why does my result look too high or low?
Check rate format, delay units, horizon, and that only one variable changed between scenarios. See the full calculator FAQ.
Next steps
Save three scenarios: start now, delay 6 months, and delay 12 months. Compare the estimated opportunity cost side-by-side.