Current-plan and required-path balances across the target horizonUpdates with every input
Everyday Calculators
Weekly Budget Target Calculator
Solve the weekly contribution required to reach a cash target, project the current plan, and test the required amount against affordable weekly margin.
Starting target gap —
Required weekly contribution —
Projected balance at current plan —
Projected surplus or shortfall —
Required contribution rate —
Affordable weekly contribution —
Affordability difference —
Target outcome —
Contribution trajectory
Contribution trajectory
Current-plan and required-path balances across the target horizon
The trajectory separates the existing plan from the exact payment path. The target line remains fixed so a shortfall cannot be hidden by percentage progress.
Current scenario Decision boundary or comparison
How to use the weekly savings target path
- Use a named amount and date.
- Enter only money already dedicated to the target.
- Use an attainable yield assumption.
- Enter committed spending before judging affordability.
Weekly savings target path fundamentals
How the target path is solved
The formula values the current balance and a stream of end-of-week contributions at the target week. When yield is zero, the remaining gap is simply divided by the weeks left.
The model does not count an uncommitted future windfall.
Calculation method
Solve the future-value annuity for the weekly contribution, then test affordability
The model compounds the opening balance and end-of-week contributions at an equivalent weekly yield. It then compares the mathematically required contribution with cash left after committed spending and a preserved income margin.
Detailed calculation process and general formulas
i = (1 + y)^(1/52) - 1FV_current = B0 x (1 + i)^n + P x [((1 + i)^n - 1) / i]P_required = [T - B0 x (1 + i)^n] x i / [(1 + i)^n - 1]P_required = (T - B0) / n when i = 0Margin_floor = I x mP_affordable = max(I - C - Margin_floor, 0)Affordability = P_affordable - P_required What each symbol means
- B0
- current balance assigned to the targetcurrency
- T
- desired balance at the target datecurrency
- n
- weeks remainingweeks
- y
- assumed effective annual yielddecimal/year
- i
- equivalent weekly yielddecimal/week
- P
- end-of-week contributioncurrency/week
- I
- weekly take-home incomecurrency/week
- C
- weekly committed spendingcurrency/week
- m
- income margin preserveddecimal
The live worked example later on this page substitutes the current inputs into these formulas and reconciles the final result.
Reading the analysis
Separate mathematical need from affordability
Required contribution answers what the target demands. Affordable contribution answers what the current weekly budget can support while preserving the selected margin.
A positive affordability difference creates resilience; a negative difference requires a change in amount, date, income, or commitments.
Improving the plan
Improve a weak target plan
- Extend the deadline deliberately.
- Reduce the target only if the underlying need changes.
- Redirect finished debt payments or canceled expenses.
- Automate the contribution and review progress monthly.
Target recovery ladder
Choose the smallest honest intervention that closes the target gap
The required weekly contribution is a mathematical demand; the affordable contribution is a budget constraint. When they disagree, adjust one lever deliberately instead of hiding the gap with an optimistic return assumption.
- 1 Measure the starting distance
Current target gap: —.
- 2 Price the deadline
Required weekly contribution: —, or — of take-home income.
- 3 Respect the operating budget
Affordable weekly contribution: —; difference: —.
- 4 Change the plan—not the arithmetic
Extend the date, change the target, redirect a real expense reduction, or raise reliable income.
Projected balance under the current plan—
Projected surplus or shortfall—
— Decision scale
Use conservative assumptions
Shorter horizons leave less time for compounding and recovery from missed contributions. Test at zero yield and with one or two missed weeks.
Keep emergency liquidity separate when the target itself is not the emergency fund.
More resilienceMore room for ordinary variation Less resilienceMore dependent on exact assumptions
The live result above supplies the current decision point.
Scenario comparison
Target-path checkpoints
The table changes the decision variable while holding the other current inputs constant, making the trade-off visible instead of replacing it with a generic score.
| Checkpoint | Week | Required path | Current plan | Target remaining | Interpretation |
|---|
Worked example
Your complete weekly savings target path calculation, step by step
This example follows the values currently entered above and updates whenever an input changes.
Projection boundary
What must stay true for the target path to remain useful
This deterministic model excludes tax, account fees, variable returns, contribution timing within a week, withdrawals, inflation, changing income, and market-loss sequences.
Important note
The entered yield is an assumption, not a promise. For a short-horizon or principal-sensitive goal, use an appropriate cash vehicle and test the plan at a zero or lower yield.
Frequently asked questions
Why might required contribution be zero?
The current balance may already reach the target after assumed growth, or the target may not exceed the current balance.
Are contributions made at the beginning or end of each week?
The formula assumes end-of-week contributions, which is slightly more conservative than beginning-of-week deposits.
Can I use an investment return for a short-term target?
Only if the risk matches the need. Principal-sensitive short-term goals often require a much more conservative assumption.
What does affordable contribution mean?
It is income remaining after entered commitments and the selected preserved margin; it is not a recommendation to use every available dollar.
How should missed weeks be handled?
Reduce the remaining week count, update the current balance, and recalculate rather than pretending the original schedule still applies.