How to calculate a rent increase

The formula takes about 10 seconds and works in every state. Here it is, with examples and the state-cap check most tenants forget.

The formula

((new_rent − old_rent) ÷ old_rent) × 100 = % increase

Subtract your old rent from your new rent.
Divide that difference by your old rent.
Multiply by 100 to get the percentage.

Worked example

Your rent was $2,000. Your landlord wants $2,150.

2,150 − 2,000 = 150
150 ÷ 2,000 = 0.075
0.075 × 100 = 7.5% increase

In dollars: $150/month more, or $1,800 over a year.

Then check the cap

A percentage alone doesn't tell you if the increase is legal — you have to compare it to your state's rules.

California: AB 1482 caps most annual increases at 5% + local CPI, max 10%.
Oregon: ~10% cap statewide (recalculated yearly).
New York (rent-stabilized): the Rent Guidelines Board sets the % each year (typically 2–3% for a 1-year renewal).
Most other states: no percentage cap, but a required 30–90 days of written notice.

CPI-based increases

Some California and Oregon ordinances tie the cap to 5% + local CPI, capped at 10%. If your area's CPI rose 3.2%, the ceiling is 8.2% — anything above that is generally not enforceable.

Try the calculator

Skip the math — enter your numbers and we'll apply your state's cap and notice rule.

FAQ

How do you calculate a rent increase?

Subtract your old rent from your new rent, divide by your old rent, then multiply by 100. Example: ($2,150 − $2,000) ÷ $2,000 × 100 = 7.5%.

How do I calculate a CPI rent increase?

CPI-based increases (used in some California and Oregon ordinances) take last year's local CPI change and add a fixed percentage — often 5%, capped at 10%. If local CPI rose 3.2%, the maximum allowed is 8.2%. Your city's rent board publishes the exact number each year.

How do I calculate a percentage rent increase from a dollar amount?

Take the dollar increase, divide by the old rent, multiply by 100. If your rent went up $150 from $2,000, that's $150 ÷ $2,000 × 100 = 7.5%.

What percentage rent increase is reasonable?

3–5% per year is typical in most US markets. 5–8% is on the high side but usually legal in states without caps. Above 10% is worth pushing back on, and above your state's statutory cap is generally not enforceable.

Educational content — not legal advice. If your increase appears to exceed your state's cap or notice rule, consider consulting a licensed tenant-rights attorney.