Updated Rent Change Tool

Rent Increase Calculator

Calculate new rent from a percentage or fixed amount, check increases against rent caps and build year-over-year rent change tables using clear, formula-based results.

Percentage Increase Fixed Amount Increase Rent Cap Compliance Year-Over-Year Table

Interactive Rent Increase Calculator With MathJS

Enter your current rent and choose a calculation mode. You can work with percentage increases, fixed amount increases, rent cap limits or an annual rent growth table. All modes use clear formulas evaluated through MathJS so you can see how each value is derived.

This mode uses the formula newRent = currentRent × (1 + percent ÷ 100) and increaseAmount = newRent − currentRent.

This mode uses the formula newRent = currentRent + increaseAmount and increasePercent = (increaseAmount ÷ currentRent) × 100.

This mode uses maxNewRent = currentRent × (1 + cap ÷ 100). The calculator compares your proposed new rent to this maximum.

This mode uses the compound formula rentYearN = startRent × (1 + p ÷ 100)N to show rent after each yearly increase.

Rent Increase Calculator – Explore Percentage, Amount And Rent Caps

The Rent Increase Calculator helps tenants and landlords explore how rent changes affect monthly and annual housing costs. Instead of doing manual calculations, you can enter your current rent and either a percentage increase, a fixed amount or a rent cap limit and get instant results. The tool is powered by MathJS, so each mode is based on clear algebraic formulas.

There are four main modes: percentage increase, fixed amount increase, rent cap compliance and a year-over-year table that illustrates how rent evolves over time when the same percentage increase is applied every year.

Percentage Rent Increase Formula

When a rent change is described as a percentage, the core formula is a simple percentage increase applied to the current rent. Let C be the current monthly rent and p be the percentage increase. The new rent N is computed as:

N = C × (1 + p ÷ 100)

The increase amount A in currency units is:

A = N − C

The calculator uses MathJS to implement these formulas. In code form, the new rent is evaluated as:

newRent = math.evaluate("current * (1 + p/100)", { current: C, p: p })

This expression multiplies the current rent by the growth factor 1 + p ÷ 100. If p is positive, rent increases. If p is negative, the factor is less than one and rent decreases. The annual rent after the increase is simply:

Annual rent = 12 × N

Fixed Amount Rent Increase Formula

Sometimes a rent change is expressed as a fixed currency amount instead of a percentage. Let C be the current monthly rent and A be the increase amount. The new rent N is:

N = C + A

The implied percentage increase p can be recovered using:

p = (A ÷ C) × 100

In MathJS form, the new rent and the percentage are computed as:

newRent = math.evaluate("current + inc", { current: C, inc: A })
percent = math.evaluate("(inc / current) * 100", { current: C, inc: A })

Annual figures are then derived by multiplying the monthly numbers by 12. This is useful for quickly comparing how a fixed increase affects yearly housing costs.

Rent Cap Or Maximum Allowed Increase

In many regions, rent caps or rent control rules restrict how much landlords can increase rent in a single period. If C is the current rent and c is the maximum allowed percentage increase, then the maximum legal new rent Nmax is:

Nmax = C × (1 + c ÷ 100)

The maximum allowed increase amount Amax is:

Amax = Nmax − C

With MathJS, these formulas are evaluated as:

maxNew = math.evaluate("current * (1 + cap/100)", { current: C, cap: c })
maxInc = math.evaluate("maxNew - current", { current: C, maxNew: Nmax })

The Rent Cap mode also takes a proposed new rent P and computes its implied percentage increase:

p = (P − C) ÷ C × 100

The calculator then compares p with the cap c and reports whether the proposal is within the cap, exactly equal to it or above the allowed increase.

Year-Over-Year Rent Change Formula

Rent is ofteniewed annually. If the same percentage increase p is applied every year, then the rent follows a compound growth pattern. Let C be the starting rent and N be the number of years. The rent after N years, RN, is:

RN = C × (1 + p ÷ 100)N

The yearly increase for year N is RN − RN−1, and the total percentage changeative to the start is:

totalChangePercent = (RN − C) ÷ C × 100

The calculator uses MathJS to build the table row by row, for example:

rentN = math.evaluate("start * pow(1 + p/100, n)", { start: C, p: p, n: N })

This is a compact way to express compound rent growth with a clear link to the underlying formula. The table makes it easy to see how small annual percentage increases can accumulate into large changes over a longer horizon.

Using The Rent Increase Calculator Step-By-Step

  • Select the mode that matches your question: percentage, fixed amount, rent cap or year-over-year.
  • Enter your current monthly rent and any other inputs such as percentage, fixed amount, rent cap or number of years.
  • Choose the number of decimal places to control how results are displayed.
  • Click the calculate button to see new rent, increase amount, implied percentage and annual figures.
  • Switch to the rent cap mode to check whether a proposed increase is within a percentage limit.
  • Use the year-over-year mode when you want to see rent projections over several years with the same increase rate.

Interpreting Results As A Tenant Or Landlord

Tenants can use the calculator to understand how a proposed increase compares to their current rent and to assess affordability. Landlords can use it to design rent changes that are transparent and easy to explain, especially when they need to comply with percentage-based caps or internal company guidelines.

The formulas are symmetric: if you know the percentage, you can get the amount; if you know the amount, you can recover the percentage. The rent cap mode makes thisationship explicit by comparing the implied percentage of a proposal to the allowed maximum.

Limitations And Practical Considerations

  • The calculator does not automatically know local rent control laws or caps; you must enter them yourself.
  • Real leases may include fees, utilities or other charges that are not part of base rent, so those need separate consideration.
  • Year-over-year projections assume the same percentage increase every year, while in practice increases may vary over time.
  • Results are numeric illustrations and should be combined with legal advice and lease documents for final decisions.

Rent Increase FAQs

Frequently Asked Questions Rent Increases

Understand the formulas behind rent changes, rent caps and long-term rent growth.

Multiply your current rent by 1.05. For example, if your rent is 1,500 and the increase is 5%, the new rent is 1,500 × 1.05 = 1,575. The calculator applies exactly this formula using MathJS.

Divide the increase amount by the original rent and multiply by 100. If your rent goes from 1,500 to 1,650, the increase is 150 and the percentage is (150 ÷ 1,500) × 100 = 10%. The Fixed Amount mode computes this value automatically.

Multiply your current rent by 1.07. For example, with a current rent of 2,000, the maximum allowed new rent is 2,000 × 1.07 = 2,140. The Rent Cap mode uses this formula and shows both the maximum rent and the maximum allowed increase amount.

Yes. Enter a negative percentage, such as −5, to represent a 5 percent rent reduction. The formulas still apply, because 1 + (−5 ÷ 100) = 0.95, which multiplies the current rent by 0.95 and lowers the amount accordingly.

The table is based on compound growth. Each year’s increase is calculated on the new, higher rent, not the original rent. The formula uses powers of 1 + p ÷ 100, so the absolute increase in currency units grows over time even if the percentage rate stays the same.

Decimal places control formatting. Internally, MathJS performs the calculations with full precision. The decimal setting simply rounds the displayed numbers so they are easy to read and practical for real-world rent amounts.

No. The tool is designed for understanding and planning, not for generating official notices. Always refer to local housing authorities, leases and legal guidelines when drafting or responding to rent increase notices.

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